Use lib flag to get debug

This should hopefully make the compiler pass thing I want to do possible

HindleyMilner.hs

@@ -1,920 +0,0 @@
-{-# LANGUAGE GeneralizedNewtypeDeriving #-}
-{-# LANGUAGE LambdaCase                 #-}
-{-# LANGUAGE OverloadedLists            #-}
-{-# LANGUAGE OverloadedStrings          #-}
-
-
-
--- | This module is an extensively documented walkthrough for typechecking a
--- basic functional language using the Hindley-Damas-Milner algorithm.
---
--- In the end, we'll be able to infer the type of expressions like
---
--- @
--- find (λx. (>) x 0)
---   :: [Integer] -> Either () Integer
--- @
---
--- It can be used in multiple different forms:
---
---  * The source is written in literate programming style, so you can almost
---    read it from top to bottom, minus some few references to later topics.
---  * /Loads/ of doctests (runnable and verified code examples) are included
---  * The code is runnable in GHCi, all definitions are exposed.
---  * A small main module that gives many examples of what you might try out in
---    GHCi is also included.
---  * The Haddock output yields a nice overview over the definitions given, with
---    a nice rendering of a truckload of Haddock comments.
-
-module HindleyMilner where
-
-import           Control.Monad.Trans
-import           Control.Monad.Trans.Except
-import           Control.Monad.Trans.State
-import           Data.Map                   (Map)
-import qualified Data.Map                   as M
-import           Data.Monoid
-import           Data.Set                   (Set)
-import qualified Data.Set                   as S
-import           Data.String
-import           Data.Text                  (Text)
-import qualified Data.Text                  as T
-
-
-
--- $setup
---
--- For running doctests:
---
--- >>> :set -XOverloadedStrings
--- >>> :set -XOverloadedLists
--- >>> :set -XLambdaCase
--- >>> import qualified Data.Text.IO as T
--- >>> let putPprLn = T.putStrLn . ppr
-
-
-
--- #############################################################################
--- #############################################################################
--- * Preliminaries
--- #############################################################################
--- #############################################################################
-
-
-
--- #############################################################################
--- ** Prettyprinting
--- #############################################################################
-
-
-
--- | A prettyprinter class. Similar to 'Show', but with a focus on having
--- human-readable output as opposed to being valid Haskell.
-class Pretty a where
-    ppr :: a -> Text
-
-
-
--- #############################################################################
--- ** Names
--- #############################################################################
-
-
-
--- | A 'name' is an identifier in the language we're going to typecheck.
--- Variables on both the term and type level have 'Name's, for example.
-newtype Name = Name Text
-    deriving (Eq, Ord, Show)
-
--- | >>> "lorem" :: Name
--- Name "lorem"
-instance IsString Name where
-    fromString = Name . T.pack
-
--- | >>> putPprLn (Name "var")
--- var
-instance Pretty Name where
-    ppr (Name n) = n
-
-
-
--- #############################################################################
--- ** Monotypes
--- #############################################################################
-
-
-
--- | A monotype is an unquantified/unparametric type, in other words it contains
--- no @forall@s. Monotypes are the inner building blocks of all types. Examples
--- of monotypes are @Int@, @a@, @a -> b@.
---
--- In formal notation, 'MType's are often called τ (tau) types.
-data MType = TVar Name           -- ^ @a@
-           | TFun MType MType    -- ^ @a -> b@
-           | TConst Name         -- ^ @Int@, @()@, …
-
-           -- Since we can't declare our own types in our simple type system
-           -- here, we'll hard-code certain basic ones so we can typecheck some
-           -- familar functions that use them later.
-           | TList MType         -- ^ @[a]@
-           | TEither MType MType -- ^ @Either a b@
-           | TTuple MType MType  -- ^ @(a,b)@
-           deriving Show
-
--- | >>> putPprLn (TFun (TEither (TVar "a") (TVar "b")) (TFun (TVar "c") (TVar "d")))
--- Either a b → c → d
---
--- Using the 'IsString' instance:
---
--- >>> putPprLn (TFun (TEither "a" "b") (TFun "c" "d"))
--- Either a b → c → d
-instance Pretty MType where
-    ppr = go False
-      where
-        go _ (TVar name)   = ppr name
-        go _ (TList a)     = "[" <> ppr a <> "]"
-        go _ (TEither l r) = "Either " <> ppr l <> " " <> ppr r
-        go _ (TTuple a b)  = "(" <> ppr a <> ", " <> ppr b <> ")"
-        go _ (TConst name) = ppr name
-        go parenthesize (TFun a b)
-            | parenthesize = "(" <> lhs <> " → " <> rhs <> ")"
-            | otherwise    =        lhs <> " → " <> rhs
-            where lhs = go True a
-                  rhs = go False b
-
--- | >>> "var" :: MType
--- TVar (Name "var")
-instance IsString MType where
-    fromString = TVar . fromString
-
-
-
--- | The free variables of an 'MType'. This is simply the collection of all the
--- individual type variables occurring inside of it.
---
--- __Example:__ The free variables of @a -> b@ are @a@ and @b@.
-freeMType :: MType -> Set Name
-freeMType = \case
-    TVar a      -> [a]
-    TFun a b    -> freeMType a <> freeMType b
-    TList a     -> freeMType a
-    TEither l r -> freeMType l <> freeMType r
-    TTuple a b  -> freeMType a <> freeMType b
-    TConst _    -> []
-
-
-
--- | Substitute all the contained type variables mentioned in the substitution,
--- and leave everything else alone.
-instance Substitutable MType where
-    applySubst s = \case
-        TVar a -> let Subst s' = s
-                  in M.findWithDefault (TVar a) a s'
-        TFun f x    -> TFun (applySubst s f) (applySubst s x)
-        TList a     -> TList (applySubst s a)
-        TEither l r -> TEither (applySubst s l) (applySubst s r)
-        TTuple a b  -> TTuple (applySubst s a) (applySubst s b)
-        c@TConst {} -> c
-
-
-
--- #############################################################################
--- ** Polytypes
--- #############################################################################
-
--- | A polytype is a monotype universally quantified over a number of type
--- variables. In Haskell, all definitions have polytypes, but since the @forall@
--- is implicit they look a bit like monotypes, maybe confusingly so. For
--- example, the type of @1 :: Int@ is actually @forall <nothing>. Int@, and the
--- type of @id@ is @forall a. a -> a@, although GHC displays it as @a -> a@.
---
--- A polytype claims to work "for all imaginable type parameters", very similar
--- to how a lambda claims to work "for all imaginable value parameters". We can
--- insert a value into a lambda's parameter to evaluate it to a new value, and
--- similarly we'll later insert types into a polytype's quantified variables to
--- gain new types.
---
--- __Example:__ in a definition @id :: forall a. a -> a@, the @a@ after the
--- ∀ ("forall") is the collection of type variables, and @a -> a@ is the 'MType'
--- quantified over. When we have such an @id@, we also have its specialized
--- version @Int -> Int@ available. This process will be the topic of the type
--- inference/unification algorithms.
---
--- In formal notation, 'PType's are often called σ (sigma) types.
---
--- The purpose of having monotypes and polytypes is that we'd like to only have
--- universal quantification at the top level, restricting our language to rank-1
--- polymorphism, where type inferece is total (all types can be inferred) and
--- simple (only a handful of typing rules). Weakening this constraint would be
--- easy: if we allowed universal quantification within function types we would
--- get rank-N polymorphism. Taking it even further to allow it anywhere,
--- effectively replacing all occurrences of 'MType' with 'PType', yields
--- impredicative types. Both these extensions make the type system
--- *significantly* more complex though.
-data PType = Forall (Set Name) MType -- ^ ∀{α}. τ
-
--- | >>> putPprLn (Forall ["a"] (TFun "a" "a"))
--- ∀a. a → a
-instance Pretty PType where
-    ppr (Forall qs mType) = "∀" <> pprUniversals <> ". " <> ppr mType
-      where
-        pprUniversals
-          | S.null qs = "∅"
-          | otherwise = (T.intercalate " " . map ppr . S.toList) qs
-
-
-
--- | The free variables of a 'PType' are the free variables of the contained
--- 'MType', except those universally quantified.
---
--- >>> let sigma = Forall ["a"] (TFun "a" (TFun (TTuple "b" "a") "c"))
--- >>> putPprLn sigma
--- ∀a. a → (b, a) → c
--- >>> let display = T.putStrLn . T.intercalate ", " . foldMap (\x -> [ppr x])
--- >>> display (freePType sigma)
--- b, c
-freePType :: PType -> Set Name
-freePType (Forall qs mType) = freeMType mType `S.difference` qs
-
-
-
--- | Substitute all the free type variables.
-instance Substitutable PType where
-    applySubst (Subst subst) (Forall qs mType) =
-        let qs' = M.fromSet (const ()) qs
-            subst' = Subst (subst `M.difference` qs')
-        in Forall qs (applySubst subst' mType)
-
-
-
--- #############################################################################
--- ** The environment
--- #############################################################################
-
-
-
--- | The environment consists of all the values available in scope, and their
--- associated polytypes. Other common names for it include "(typing) context",
--- and because of the commonly used symbol for it sometimes directly
--- \"Gamma"/@"Γ"@.
---
--- There are two kinds of membership in an environment,
---
---   - @∈@: an environment @Γ@ can be viewed as a set of @(value, type)@ pairs,
---     and we can test whether something is /literally contained/ by it via
---     x:σ ∈ Γ
---   - @⊢@, pronounced /entails/, describes all the things that are well-typed,
---     given an environment @Γ@. @Γ ⊢ x:τ@ can thus be seen as a judgement that
---     @x:τ@ is /figuratively contained/ in @Γ@.
---
--- For example, the environment @{x:Int}@ literally contains @x@, but given
--- this, it also entails @λy. x@, @λy z. x@, @let id = λy. y in id x@ and so on.
---
--- In Haskell terms, the environment consists of all the things you currently
--- have available, or that can be built by comining them. If you import the
--- Prelude, your environment entails
---
--- @
--- id            →  ∀a. a→a
--- map           →  ∀a b. (a→b) → [a] → [b]
--- putStrLn      →  ∀∅. String → IO ()
--- …
--- id map        →  ∀a b. (a→b) → [a] → [b]
--- map putStrLn  →  ∀∅. [String] -> [IO ()]
--- …
--- @
-newtype Env = Env (Map Name PType)
-
--- | >>> :{
---    putPprLn (Env
---        [ ("id", Forall ["a"] (TFun "a" "a"))
---        , ("const", Forall ["a", "b"] (TFun "a" (TFun "b" "a"))) ])
--- :}
--- Γ = { const : ∀a b. a → b → a
---     , id : ∀a. a → a }
-instance Pretty Env where
-    ppr (Env env) = "Γ = { " <> T.intercalate "\n    , " pprBindings <> " }"
-      where
-        bindings = M.assocs env
-        pprBinding (name, pType) = ppr name <> " : " <> ppr pType
-        pprBindings = map pprBinding bindings
-
-
-
--- | The free variables of an 'Env'ironment are all the free variables of the
--- 'PType's it contains.
-freeEnv :: Env -> Set Name
-freeEnv (Env env) = let allPTypes = M.elems env
-                    in S.unions (map freePType allPTypes)
-
-
-
--- | Performing a 'Subst'itution in an 'Env'ironment means performing that
--- substituion on all the contained 'PType's.
-instance Substitutable Env where
-    applySubst s (Env env) = Env (M.map (applySubst s) env)
-
-
-
--- #############################################################################
--- ** Substitutions
--- #############################################################################
-
-
-
--- | A substitution is a mapping from type variables to 'MType's. Applying a
--- substitution means applying those replacements. For example, the substitution
--- @a -> Int@ applied to @a -> a@ yields the result @Int -> Int@.
---
--- A key concept behind Hindley-Milner is that once we dive deeper into an
--- expression, we learn more about our type variables. We might learn that  @a@
--- has to be specialized to @b -> b@, and then later on that @b@ is actually
--- @Int@. Substitutions are an organized way of carrying this information along.
-newtype Subst = Subst (Map Name MType)
-
-
-
--- | We're going to apply substitutions to a variety of other values that
--- somehow contain type variables, so we overload this application operation in
--- a class here.
---
--- Laws:
---
--- @
--- 'applySubst' 'mempty' ≡ 'id'
--- 'applySubst' (s1 '<>' s2) ≡ 'applySubst' s1 . 'applySubst' s2
--- @
-class Substitutable a where
-    applySubst :: Subst -> a -> a
-
-instance (Substitutable a, Substitutable b) => Substitutable (a,b) where
-    applySubst s (x,y) = (applySubst s x, applySubst s y)
-
--- | @'applySubst' s1 s2@ applies one substitution to another, replacing all the
--- bindings in the second argument @s2@ with their values mentioned in the first
--- one (@s1@).
-instance Substitutable Subst where
-    applySubst s (Subst target) = Subst (fmap (applySubst s) target)
-
--- | >>> :{
---    putPprLn (Subst
---        [ ("a", TFun "b" "b")
---        , ("b", TEither "c" "d") ])
--- :}
--- { a ––> b → b
--- , b ––> Either c d }
-instance Pretty Subst where
-    ppr (Subst s) = "{ " <> T.intercalate "\n, " [ ppr k <> " ––> " <> ppr v | (k,v) <- M.toList s ] <> " }"
-
--- | Combine two substitutions by applying all substitutions mentioned in the
--- first argument to the type variables contained in the second.
-instance Monoid Subst where
-    -- Considering that all we can really do with a substitution is apply it, we
-    -- can use the one of 'Substitutable's laws to show that substitutions
-    -- combine associatively,
-    --
-    -- @
-    --   applySubst (compose s1 (compose s2 s3))
-    -- = applySubst s1 . applySubst (compose s2 s3)
-    -- = applySubst s1 . applySubst s2 . applySubst s3
-    -- = applySubst (compose s1 s2) . applySubst s3
-    -- = applySubst (compose (compose s1 s2) s3)
-    -- @
-    mappend subst1 subst2 = Subst (s1 `M.union` s2)
-      where
-        Subst s1 = subst1
-        Subst s2 = applySubst subst1 subst2
-
-    mempty = Subst M.empty
-
-
-
--- #############################################################################
--- #############################################################################
--- * Typechecking
--- #############################################################################
--- #############################################################################
-
--- $ Typechecking does two things:
---
--- 1. If two types are not immediately identical, attempt to 'unify' them
---    to get a type compatible with both of them
--- 2. 'infer' the most general type of a value by comparing the values in its
---    definition with the 'Env'ironment
-
-
-
--- #############################################################################
--- ** Inference context
--- #############################################################################
-
-
-
--- | The inference type holds a supply of unique names, and can fail with a
--- descriptive error if something goes wrong.
---
--- /Invariant:/ the supply must be infinite, or we might run out of names to
--- give to things.
-newtype Infer a = Infer (ExceptT InferError (State [Name]) a)
-    deriving (Functor, Applicative, Monad)
-
--- | Errors that can happen during the type inference process.
-data InferError =
-    -- | Two types that don't match were attempted to be unified.
-    --
-    -- For example, @a -> a@ and @Int@ do not unify.
-    --
-    -- >>> putPprLn (CannotUnify (TFun "a" "a") (TConst "Int"))
-    -- Cannot unify a → a with Int
-      CannotUnify MType MType
-
-    -- | A 'TVar' is bound to an 'MType' that already contains it.
-    --
-    -- The canonical example of this is @λx. x x@, where the first @x@
-    -- in the body has to have type @a -> b@, and the second one @a@. Since
-    -- they're both the same @x@, this requires unification of @a@ with
-    -- @a -> b@, which only works if @a = a -> b = (a -> b) -> b = …@, yielding
-    -- an infinite type.
-    --
-    -- >>> putPprLn (OccursCheckFailed "a" (TFun "a" "a"))
-    -- Occurs check failed: a already appears in a → a
-    | OccursCheckFailed Name MType
-
-    -- | The value of an unknown identifier was read.
-    --
-    -- >>> putPprLn (UnknownIdentifier "a")
-    -- Unknown identifier: a
-    | UnknownIdentifier Name
-    deriving Show
-
--- | >>> putPprLn (CannotUnify (TEither "a" "b") (TTuple "a" "b"))
--- Cannot unify Either a b with (a, b)
-instance Pretty InferError where
-    ppr = \case
-        CannotUnify t1 t2 ->
-            "Cannot unify " <> ppr t1 <> " with " <> ppr t2
-        OccursCheckFailed name ty ->
-            "Occurs check failed: " <> ppr name <> " already appears in " <> ppr ty
-        UnknownIdentifier name ->
-            "Unknown identifier: " <> ppr name
-
-
-
--- | Evaluate a value in an 'Infer'ence context.
---
--- >>> let expr = EAbs "f" (EAbs "g" (EAbs "x" (EApp (EApp "f" "x") (EApp "g" "x"))))
--- >>> putPprLn expr
--- λf g x. f x (g x)
--- >>> let inferred = runInfer (infer (Env []) expr)
--- >>> let demonstrate = \case Right (_, ty) -> T.putStrLn (":: " <> ppr ty)
--- >>> demonstrate inferred
--- :: (c → e → f) → (c → e) → c → f
-runInfer :: Infer a -- ^ Inference data
-         -> Either InferError a
-runInfer (Infer inf) =
-    evalState (runExceptT inf) (map Name (infiniteSupply alphabet))
-  where
-
-    alphabet = map T.singleton ['a'..'z']
-
-    -- [a, b, c] ==> [a,b,c, a1,b1,c1, a2,b2,c2, …]
-    infiniteSupply supply = supply <> addSuffixes supply (1 :: Integer)
-      where
-        addSuffixes xs n = map (\x -> addSuffix x n) xs <> addSuffixes xs (n+1)
-        addSuffix x n = x <> T.pack (show n)
-
-
-
--- | Throw an 'InferError' in an 'Infer'ence context.
---
--- >>> case runInfer (throw (UnknownIdentifier "var")) of Left err -> putPprLn err
--- Unknown identifier: var
-throw :: InferError -> Infer a
-throw = Infer . throwE
-
-
-
--- #############################################################################
--- ** Unification
--- #############################################################################
-
--- $ Unification describes the process of making two different types compatible
--- by specializing them where needed. A desirable property to have here is being
--- able to find the most general unifier. Luckily, we'll be able to do that in
--- our type system.
-
-
-
--- | The unification of two 'MType's is the most general substituion that can be
--- applied to both of them in order to yield the same result.
---
--- >>> let m1 = TFun "a" "b"
--- >>> putPprLn m1
--- a → b
--- >>> let m2 = TFun "c" (TEither "d" "e")
--- >>> putPprLn m2
--- c → Either d e
--- >>> let inferSubst = unify (m1, m2)
--- >>> case runInfer inferSubst of Right subst -> putPprLn subst
--- { a ––> c
--- , b ––> Either d e }
-unify :: (MType, MType) -> Infer Subst
-unify = \case
-    (TFun a b,    TFun x y)          -> unifyBinary (a,b) (x,y)
-    (TVar v,      x)                 -> v `bindVariableTo` x
-    (x,           TVar v)            -> v `bindVariableTo` x
-    (TConst a,    TConst b) | a == b -> pure mempty
-    (TList a,     TList b)           -> unify (a,b)
-    (TEither a b, TEither x y)       -> unifyBinary (a,b) (x,y)
-    (TTuple a b,  TTuple x y)        -> unifyBinary (a,b) (x,y)
-    (a, b)                           -> throw (CannotUnify a b)
-
-  where
-
-    -- Unification of binary type constructors, such as functions and Either.
-    -- Unification is first done for the first operand, and assuming the
-    -- required substitution, for the second one.
-    unifyBinary :: (MType, MType) -> (MType, MType) -> Infer Subst
-    unifyBinary (a,b) (x,y) = do
-        s1 <- unify (a, x)
-        s2 <- unify (applySubst s1 (b, y))
-        pure (s1 <> s2)
-
-
-
--- | Build a 'Subst'itution that binds a 'Name' of a 'TVar' to an 'MType'. The
--- resulting substitution should be idempotent, i.e. applying it more than once
--- to something should not be any different from applying it only once.
---
--- - In the simplest case, this just means building a substitution that just
---   does that.
--- - Substituting a 'Name' with a 'TVar' with the same name unifies a type
---   variable with itself, and the resulting substitution does nothing new.
--- - If the 'Name' we're trying to bind to an 'MType' already occurs in that
---   'MType', the resulting substitution would not be idempotent: the 'MType'
---   would be replaced again, yielding a different result. This is known as the
---   Occurs Check.
-bindVariableTo :: Name -> MType -> Infer Subst
-
-bindVariableTo name (TVar v) | boundToSelf = pure mempty
-  where
-    boundToSelf = name == v
-
-bindVariableTo name mType | name `occursIn` mType = throw (OccursCheckFailed name mType)
-  where
-    n `occursIn` ty = n `S.member` freeMType ty
-
-bindVariableTo name mType = pure (Subst (M.singleton name mType))
-
-
-
--- #############################################################################
--- ** Type inference
--- #############################################################################
-
--- $ Type inference is the act of finding out a value's type by looking at the
--- environment it is in, in order to make it compatible with it.
---
--- In literature, the Hindley-Damas-Milner inference algorithm ("Algorithm W")
--- is often presented in the style of logical formulas, and below you'll find
--- that version along with code that actually does what they say.
---
--- These formulas look a bit like fractions, where the "numerator" is a
--- collection of premises, and the denominator is the consequence if all of them
--- hold.
---
--- __Example:__
---
--- @
--- Γ ⊢ even : Int → Bool   Γ ⊢ 1 : Int
--- –––––––––––––––––––––––––––––––––––
---          Γ ⊢ even 1 : Bool
--- @
---
--- means that if we have a value of type @Int -> Bool@ called "even" and a value
--- of type @Int@ called @1@, then we also have a value of type @Bool@ via
--- @even 1@ available to us.
---
--- The actual inference rules are polymorphic versions of this example, and
--- the code comments will explain each step in detail.
-
-
-
--- -----------------------------------------------------------------------------
--- *** The language: typed lambda calculus
--- -----------------------------------------------------------------------------
-
-
-
--- | The syntax tree of the language we'd like to typecheck. You can view it as
--- a close relative to simply typed lambda calculus, having only the most
--- necessary syntax elements.
---
--- Since 'ELet' is non-recursive, the usual fixed-point function
--- @fix : (a → a) → a@ can be introduced to allow recursive definitions.
-data Exp = ELit Lit          -- ^ True, 1
-         | EVar Name         -- ^ @x@
-         | EApp Exp Exp      -- ^ @f x@
-         | EAbs Name Exp     -- ^ @λx. e@
-         | ELet Name Exp Exp -- ^ @let x = e in e'@ (non-recursive)
-         deriving Show
-
-
-
--- | Literals we'd like to support. Since we can't define new data types in our
--- simple type system, we'll have to hard-code the possible ones here.
-data Lit = LBool Bool
-         | LInteger Integer
-         deriving Show
-
-
-
--- | >>> putPprLn (EAbs "f" (EAbs "g" (EAbs "x" (EApp (EApp "f" "x") (EApp "g" "x")))))
--- λf g x. f x (g x)
-instance Pretty Exp where
-    ppr (ELit lit) = ppr lit
-
-    ppr (EVar name) = ppr name
-
-    ppr (EApp f x) = pprApp1 f <> " " <> pprApp2 x
-      where
-        pprApp1 = \case
-            eLet@ELet{} -> "(" <> ppr eLet <> ")"
-            eLet@EAbs{} -> "(" <> ppr eLet <> ")"
-            e -> ppr e
-        pprApp2 = \case
-            eApp@EApp{} -> "(" <> ppr eApp <> ")"
-            e -> pprApp1 e
-
-    ppr x@EAbs{} = pprAbs True x
-      where
-        pprAbs True  (EAbs name expr) = "λ" <> ppr name <> pprAbs False expr
-        pprAbs False (EAbs name expr) = " " <> ppr name <> pprAbs False expr
-        pprAbs _ expr                 = ". " <> ppr expr
-
-    ppr (ELet name value body) =
-        "let " <> ppr name <> " = " <> ppr value <> " in " <> ppr body
-
--- | >>> putPprLn (LBool True)
--- True
---
--- >>> putPprLn (LInteger 127)
--- 127
-instance Pretty Lit where
-    ppr = \case
-        LBool    b -> showT b
-        LInteger i -> showT i
-      where
-        showT :: Show a => a -> Text
-        showT = T.pack . show
-
--- | >>> "var" :: Exp
--- EVar (Name "var")
-instance IsString Exp where
-    fromString = EVar . fromString
-
-
-
--- -----------------------------------------------------------------------------
--- *** Some useful definitions
--- -----------------------------------------------------------------------------
-
-
-
--- | Generate a fresh 'Name' in a type 'Infer'ence context. An example use case
--- of this is η expansion, which transforms @f@ into @λx. f x@, where "x" is a
--- new name, i.e. unbound in the current context.
-fresh :: Infer MType
-fresh = drawFromSupply >>= \case
-    Right name -> pure (TVar name)
-    Left err -> throw err
-
-  where
-
-    drawFromSupply :: Infer (Either InferError Name)
-    drawFromSupply = Infer (do
-        s:upply <- lift get
-        lift (put upply)
-        pure (Right s) )
-
-
-
--- | Add a new binding to the environment.
---
--- The Haskell equivalent would be defining a new value, for example in module
--- scope or in a @let@ block. This corresponds to the "comma" operation used in
--- formal notation,
---
--- @
--- Γ, x:σ  ≡  extendEnv Γ (x,σ)
--- @
-extendEnv :: Env -> (Name, PType) -> Env
-extendEnv (Env env) (name, pType) = Env (M.insert name pType env)
-
-
-
--- -----------------------------------------------------------------------------
--- *** Inferring the types of all language constructs
--- -----------------------------------------------------------------------------
-
-
-
--- | Infer the type of an 'Exp'ression in an 'Env'ironment, resulting in the
--- 'Exp's 'MType' along with a substitution that has to be done in order to reach
--- this goal.
---
--- This is widely known as /Algorithm W/.
-infer :: Env -> Exp -> Infer (Subst, MType)
-infer env = \case
-    ELit lit    -> inferLit lit
-    EVar name   -> inferVar env name
-    EApp f x    -> inferApp env f x
-    EAbs x e    -> inferAbs env x e
-    ELet x e e' -> inferLet env x e e'
-
-
-
--- | Literals such as 'True' and '1' have their types hard-coded.
-inferLit :: Lit -> Infer (Subst, MType)
-inferLit lit = pure (mempty, TConst litTy)
-  where
-    litTy = case lit of
-        LBool    {} -> "Bool"
-        LInteger {} -> "Integer"
-
-
-
--- | Inferring the type of a variable is done via
---
--- @
--- x:σ ∈ Γ   τ = instantiate(σ)
--- ––––––––––––––––––––––––––––  [Var]
---            Γ ⊢ x:τ
--- @
---
--- This means that if @Γ@ /literally contains/ (@∈@) a value, then it also
--- /entails it/ (@⊢@) in all its instantiations.
-inferVar :: Env -> Name -> Infer (Subst, MType)
-inferVar env name = do
-    sigma <- lookupEnv env name -- x:σ ∈ Γ
-    tau <- instantiate sigma    -- τ = instantiate(σ)
-                                -- ------------------
-    pure (mempty, tau)          -- Γ ⊢ x:τ
-
-
-
--- | Look up the 'PType' of a 'Name' in the 'Env'ironment.
---
--- This checks whether @x:σ@ is /literally contained/ in @Γ@. For more details
--- about this, see the documentation of 'Env'.
---
--- To give a Haskell analogon, looking up @id@ when @Prelude@ is loaded, the
--- resulting 'PType' would be @id@'s type, namely @forall a. a -> a@.
-lookupEnv :: Env -> Name -> Infer PType
-lookupEnv (Env env) name = case M.lookup name env of
-    Just x  -> pure x
-    Nothing -> throw (UnknownIdentifier name)
-
-
-
--- | Bind all quantified variables of a 'PType' to 'fresh' type variables.
---
--- __Example:__ instantiating @forall a. a -> b -> a@ results in the 'MType'
--- @c -> b -> c@, where @c@ is a fresh name (to avoid shadowing issues).
---
--- You can picture the 'PType' to be the prototype converted to an instantiated
--- 'MType', which can now be used in the unification process.
---
--- Another way of looking at it is by simply forgetting which variables were
--- quantified, carefully avoiding name clashes when doing so.
---
--- 'instantiate' can also be seen as the opposite of 'generalize', which we'll
--- need later to convert an 'MType' to a 'PType'.
-instantiate :: PType -> Infer MType
-instantiate (Forall qs t) = do
-    subst <- substituteAllWithFresh qs
-    pure (applySubst subst t)
-
-  where
-    -- For each given name, add a substitution from that name to a fresh type
-    -- variable to the result.
-    substituteAllWithFresh :: Set Name -> Infer Subst
-    substituteAllWithFresh xs = do
-        let freshSubstActions = M.fromSet (const fresh) xs
-        freshSubsts <- sequenceA freshSubstActions
-        pure (Subst freshSubsts)
-
-
-
--- | Function application captures the fact that if we have a function and an
--- argument we can give to that function, we also have the result value of the
--- result type available to us.
---
--- @
--- Γ ⊢ f : fτ   Γ ⊢ x : xτ   fxτ = fresh   unify(fτ, xτ → fxτ)
--- –––––––––––––––––––––––––––––––––––––––––––––––––––––––––––  [App]
---                       Γ ⊢ f x : fxτ
--- @
---
--- This rule says that given a function and a value with a type, the function
--- type has to unify with a function type that allows the value type to be its
--- argument.
-inferApp
-    :: Env
-    -> Exp -- ^ __f__ x
-    -> Exp -- ^ f __x__
-    -> Infer (Subst, MType)
-inferApp env f x = do
-    (s1, fTau) <- infer env f                         -- f : fτ
-    (s2, xTau) <- infer (applySubst s1 env) x         -- x : xτ
-    fxTau <- fresh                                    -- fxτ = fresh
-    s3 <- unify (applySubst s2 fTau, TFun xTau fxTau) -- unify (fτ, xτ → fxτ)
-    let s = s3 <> s2 <> s1                            -- --------------------
-    pure (s, applySubst s3 fxTau)                     -- f x : fxτ
-
-
-
--- | Lambda abstraction is based on the fact that when we introduce a new
--- variable, the resulting lambda maps from that variable's type to the type of
--- the body.
---
--- @
--- τ = fresh   σ = ∀∅. τ   Γ, x:σ ⊢ e:τ'
--- –––––––––––––––––––––––––––––––––––––  [Abs]
---             Γ ⊢ λx.e : τ→τ'
--- @
---
--- Here, @Γ, x:τ@ is @Γ@ extended by one additional mapping, namely @x:τ@.
---
--- Abstraction is typed by extending the environment by a new 'MType', and if
--- under this assumption we can construct a function mapping to a value of that
--- type, we can say that the lambda takes a value and maps to it.
-inferAbs
-    :: Env
-    -> Name -- ^ λ__x__. e
-    -> Exp  -- ^ λx. __e__
-    -> Infer (Subst, MType)
-inferAbs env x e = do
-    tau <- fresh                           -- τ = fresh
-    let sigma = Forall [] tau              -- σ = ∀∅. τ
-        env' = extendEnv env (x, sigma)    -- Γ, x:σ …
-    (s, tau') <- infer env' e              --        … ⊢ e:τ'
-                                           -- ---------------
-    pure (s, TFun (applySubst s tau) tau') -- λx.e : τ→τ'
-
-
-
--- | A let binding allows extending the environment with new bindings in a
--- principled manner. To do this, we first have to typecheck the expression to
--- be introduced. The result of this is then generalized to a 'PType', since let
--- bindings introduce new polymorphic values, which are then added to the
--- environment. Now we can finally typecheck the body of the "in" part of the
--- let binding.
---
--- Note that in our simple language, let is non-recursive, but recursion can be
--- introduced as usual by adding a primitive @fix : (a → a) → a@ if desired.
---
--- @
--- Γ ⊢ e:τ   σ = gen(Γ,τ)   Γ, x:σ ⊢ e':τ'
--- –––––––––––––––––––––––––––––––––––––––  [Let]
---         Γ ⊢ let x = e in e' : τ'
--- @
-inferLet
-    :: Env
-    -> Name -- ^ let __x__ = e in e'
-    -> Exp -- ^ let x = __e__ in e'
-    -> Exp -- ^ let x = e in __e'__
-    -> Infer (Subst, MType)
-inferLet env x e e' = do
-    (s1, tau) <- infer env e              -- Γ ⊢ e:τ
-    let env' = applySubst s1 env
-    let sigma = generalize env' tau       -- σ = gen(Γ,τ)
-    let env'' = extendEnv env' (x, sigma) -- Γ, x:σ
-    (s2, tau') <- infer env'' e'          -- Γ ⊢ …
-                                          -- --------------------------
-    pure (s2 <> s1, tau')                 --     … let x = e in e' : τ'
-
-
-
--- | Generalize an 'MType' to a 'PType' by universally quantifying over all the
--- type variables contained in it, except those already free in the environment.
---
--- >>> let tau = TFun "a" (TFun "b" "a")
--- >>> putPprLn tau
--- a → b → a
--- >>> putPprLn (generalize (Env [("x", Forall [] "b")]) tau)
--- ∀a. a → b → a
---
--- In more formal notation,
---
--- @
--- gen(Γ,τ) = ∀{α}. τ
---     where {α} = free(τ) – free(Γ)
--- @
---
--- 'generalize' can also be seen as the opposite of 'instantiate', which
--- converts a 'PType' to an 'MType'.
-generalize :: Env -> MType -> PType
-generalize env mType = Forall qs mType
-  where
-    qs = freeMType mType `S.difference` freeEnv env

Main.hs

@@ -1,185 +0,0 @@
-{-# LANGUAGE OverloadedLists   #-}
-{-# LANGUAGE OverloadedStrings #-}
-
-module Main where
-
-
-
-import qualified Data.Map     as M
-import           Data.Monoid
-import           Data.Text    (Text)
-import qualified Data.Text.IO as T
-
-import HindleyMilner
-
-
-
--- #############################################################################
--- #############################################################################
--- * Testing
--- #############################################################################
--- #############################################################################
-
-
-
--- #############################################################################
--- ** A small custom Prelude
--- #############################################################################
-
-
-
-prelude :: Env
-prelude = Env (M.fromList
-    [ ("(*)",        Forall []              (tInteger ~> tInteger ~> tInteger))
-    , ("(+)",        Forall []              (tInteger ~> tInteger ~> tInteger))
-    , ("(,)",        Forall ["a","b"]       ("a" ~> "b" ~> TTuple "a" "b"))
-    , ("(-)",        Forall []              (tInteger ~> tInteger ~> tInteger))
-    , ("(.)",        Forall ["a", "b", "c"] (("b" ~> "c") ~> ("a" ~> "b") ~> "a" ~> "c"))
-    , ("(<)",        Forall []              (tInteger ~> tInteger ~> tBool))
-    , ("(<=)",       Forall []              (tInteger ~> tInteger ~> tBool))
-    , ("(>)",        Forall []              (tInteger ~> tInteger ~> tBool))
-    , ("(>=)",       Forall []              (tInteger ~> tInteger ~> tBool))
-    , ("const",      Forall ["a","b"]       ("a" ~> "b" ~> "a"))
-    , ("Cont/>>=",   Forall ["a"]           ((("a" ~> "r") ~> "r") ~> ("a" ~> (("b" ~> "r") ~> "r")) ~> (("b" ~> "r") ~> "r")))
-    , ("find",       Forall ["a","b"]       (("a" ~> tBool) ~> TList "a" ~> tMaybe "a"))
-    , ("fix",        Forall ["a"]           (("a" ~> "a") ~> "a"))
-    , ("foldr",      Forall ["a","b"]       (("a" ~> "b" ~> "b") ~> "b" ~> TList "a" ~> "b"))
-    , ("id",         Forall ["a"]           ("a" ~> "a"))
-    , ("ifThenElse", Forall ["a"]           (tBool ~> "a" ~> "a" ~> "a"))
-    , ("Left",       Forall ["a","b"]       ("a" ~> TEither "a" "b"))
-    , ("length",     Forall ["a"]           (TList "a" ~> tInteger))
-    , ("map",        Forall ["a","b"]       (("a" ~> "b") ~> TList "a" ~> TList "b"))
-    , ("reverse",    Forall ["a"]           (TList "a" ~> TList "a"))
-    , ("Right",      Forall ["a","b"]       ("b" ~> TEither "a" "b"))
-    , ("[]",         Forall ["a"]           (TList "a"))
-    , ("(:)",        Forall ["a"]           ("a" ~> TList "a" ~> TList "a"))
-    ])
-  where
-    tBool = TConst "Bool"
-    tInteger = TConst "Integer"
-    tMaybe = TEither (TConst "()")
-
-
-
--- | Synonym for 'TFun' to make writing type signatures easier.
---
--- Instead of
---
--- @
--- Forall ["a","b"] (TFun "a" (TFun "b" "a"))
--- @
---
--- we can write
---
--- @
--- Forall ["a","b"] ("a" ~> "b" ~> "a")
--- @
-(~>) :: MType -> MType -> MType
-(~>) = TFun
-infixr 9 ~>
-
-
-
--- #############################################################################
--- ** Run it!
--- #############################################################################
-
-
-
--- | Run type inference on a cuple of values
-main :: IO ()
-main = do
-    let inferAndPrint = T.putStrLn . ("  " <>) . showType prelude
-    T.putStrLn "Well-typed:"
-    do
-        inferAndPrint (lambda ["x"] "x")
-        inferAndPrint (lambda ["f","g","x"] (apply "f" ["x", apply "g" ["x"]]))
-        inferAndPrint (lambda ["f","g","x"] (apply "f" [apply "g" ["x"]]))
-        inferAndPrint (lambda ["m", "k", "c"] (apply "m" [lambda ["x"] (apply "k" ["x", "c"])])) -- >>= for Cont
-        inferAndPrint (lambda ["f"] (apply "(.)" ["reverse", apply "map" ["f"]]))
-        inferAndPrint (apply "find" [lambda ["x"] (apply "(>)" ["x", int 0])])
-        inferAndPrint (apply "map" [apply "map" ["map"]])
-        inferAndPrint (apply "(*)" [int 1, int 2])
-        inferAndPrint (apply "foldr" ["(+)", int 0])
-        inferAndPrint (apply "map" ["length"])
-        inferAndPrint (apply "map" ["map"])
-        inferAndPrint (lambda ["x"] (apply "ifThenElse" [apply "(<)" ["x", int 0], int 0, "x"]))
-        inferAndPrint (lambda ["x"] (apply "fix" [lambda ["xs"] (apply "(:)" ["x", "xs"])]))
-    T.putStrLn "Ill-typed:"
-    do
-        inferAndPrint (apply "(*)" [int 1, bool True])
-        inferAndPrint (apply "foldr" [int 1])
-        inferAndPrint (lambda ["x"] (apply "x" ["x"]))
-        inferAndPrint (lambda ["x"] (ELet "xs" (apply "(:)" ["x", "xs"]) "xs"))
-
-
-
--- | Build multiple lambda bindings.
---
--- Instead of
---
--- @
--- EAbs "f" (EAbs "x" (EApp "f" "x"))
--- @
---
--- we can write
---
--- @
--- lambda ["f", "x"] (EApp "f" "x")
--- @
---
--- for
---
--- @
--- λf x. f x
--- @
-lambda :: [Name] -> Exp -> Exp
-lambda names expr = foldr EAbs expr names
-
-
-
--- | Apply a function to multiple arguments.
---
--- Instead of
---
--- @
--- EApp (EApp (EApp "f" "x") "y") "z")
--- @
---
--- we can write
---
--- @
--- apply "f" ["x", "y", "z"]
--- @
---
--- for
---
--- @
--- f x y z
--- @
-apply :: Exp -> [Exp] -> Exp
-apply = foldl EApp
-
-
-
--- | Construct an integer literal.
-int :: Integer -> Exp
-int = ELit . LInteger
-
-
-
--- | Construct a boolean literal.
-bool :: Bool -> Exp
-bool = ELit . LBool
-
-
-
--- | Convenience function to run type inference algorithm
-showType :: Env    -- ^ Starting environment, e.g. 'prelude'.
-         -> Exp    -- ^ Expression to typecheck
-         -> Text   -- ^ Text representation of the result. Contains an error
-                   --   message on failure.
-showType env expr =
-    case (runInfer . fmap (generalize (Env mempty) . uncurry applySubst) . infer env) expr of
-        Left err -> "Error inferring type of " <> ppr expr <>": " <> ppr err
-        Right ty -> ppr expr <> " :: " <> ppr ty

README.md

@@ -3,7 +3,7 @@
 
 Schala is a Rust framework written to make it easy to
 create and experiment with toy programming languages. It provides
-a common REPL, and a trait `ProgrammingLanguage` with provisions
+a common REPL, and a trait `ProgrammingLanguage` with provisions 
 for tokenizing text, parsing tokens, evaluating an abstract syntax tree,
 and other tasks that are common to all programming languages.
 
@@ -66,7 +66,6 @@ https://skillsmatter.com/skillscasts/10868-inside-the-rust-compiler
 
 ### Parsing
 http://journal.stuffwithstuff.com/2011/03/19/pratt-parsers-expression-parsing-made-easy/
-https://soc.github.io/languages/unified-condition-syntax
 
 [Crafting Interpreters](http://www.craftinginterpreters.com/)
 

TODO.md

@@ -2,56 +2,6 @@
 # TODO Items
 
 
-- https://nshipster.com/never/
--https://cranelift.readthedocs.io/en/latest/?badge=latest<Paste>
-
--consult http://gluon-lang.org/book/embedding-api.html
-
-- if/match playground
-
-simple if
-`if x == 1.0 { "a" } else { "b" }`
-
-one comparison multiple targets:
-`if x == { 1.0 -> "a", 2.0 -> "b", else -> "c" }`
-
-different comparison operators/ method calls:
-`if x { == 1.0 -> "a", eq NaN -> "n", .hella() -> "h", else -> "z" }`
-
-pattern matching/introducing bindings:
-`if alice { .age < 18 -> "18", is Person("Alice", age) -> "${age}", else -> "none" }`
-
-pattern matching w/ if-let:
-`if person is Person("Alice", age) { "${age}" } else { "nope" }`
-
--https://soc.github.io/languages/unified-condition-syntax syntax:
-
-`if <cond-expr>" then <then-expr> else <else-expr>`
-`if <half-expr> \n <rest-expr1> then <result1-expr> \n <rest-expr2> then <result-expr2> else <result3-expr>`
--and rest-exprs (or "targets") can have 'is' for pattern-matching, actually so can a full cond-expr
-
-UNIFIED IF EXPRESSIONS FINAL WORK:
-
-basic syntax:
-
-`if_expr := if discriminator '{' (guard_expr)* '}'`
-`guard_expr := pattern 'then' block_or_expr'`
-`pattern := rhs | is_pattern`
-`is_pattern := 'is' ???`
-`rhs := expression | ???`
-
-
-if the only two guard patterns are true and false, then the abbreviated syntax:
-`'if' discriminator 'then' block_or_expr 'else' block_or_expr`
-can replace `'if' discriminator '{' 'true' 'then' block_or_expr; 'false' 'then' block_or_expr '}'`
-
-
-
-
-- Next priorities: - get ADTs working, get matches working
-
-- inclusive/exclusive range syntax like .. vs ..=
-
 - sketch of an idea for the REPL:
         -each compiler pass should be a (procedural?) macro like
         compiler_pass!("parse", dataproducts: ["ast", "parse_tree"], {

maaru/src/lib.rs

@@ -7,7 +7,7 @@ mod parser;
 mod eval;
 mod compilation;
 
-use schala_repl::{ProgrammingLanguageInterface, EvalOptions, UnfinishedComputation, FinishedComputation, TraceArtifact};
+use schala_repl::{ProgrammingLanguageInterface, EvalOptions, LanguageOutput, TraceArtifact};
 
 #[derive(Debug)]
 pub struct TokenError {
@@ -42,37 +42,40 @@ impl<'a> ProgrammingLanguageInterface for Maaru<'a> {
     format!("maaru")
   }
 
-  fn execute_pipeline(&mut self, input: &str, options: &EvalOptions) -> FinishedComputation {
-    let mut output = UnfinishedComputation::default();
+  fn evaluate_in_repl(&mut self, input: &str, options: &EvalOptions) -> LanguageOutput {
+    let mut output = LanguageOutput::default();
 
     let tokens = match tokenizer::tokenize(input) {
       Ok(tokens) => {
-        if let Some(_) = options.debug_passes.get("tokens") {
+        if options.debug.tokens {
           output.add_artifact(TraceArtifact::new("tokens", format!("{:?}", tokens)));
         }
         tokens
       },
       Err(err) => {
-        return output.finish(Err(format!("Tokenization error: {:?}\n", err.msg)))
+        output.add_output(format!("Tokenization error: {:?}\n", err.msg));
+        return output;
       }
     };
 
     let ast = match parser::parse(&tokens, &[]) {
       Ok(ast) => {
-        if let Some(_) = options.debug_passes.get("ast") {
+        if options.debug.ast {
           output.add_artifact(TraceArtifact::new("ast", format!("{:?}", ast)));
         }
         ast
       },
       Err(err) => {
-        return output.finish(Err(format!("Parse error: {:?}\n", err.msg)))
+        output.add_output(format!("Parse error: {:?}\n", err.msg));
+        return output;
       }
     };
     let mut evaluation_output = String::new();
     for s in self.evaluator.run(ast).iter() {
       evaluation_output.push_str(s);
     }
-    output.finish(Ok(evaluation_output))
+    output.add_output(evaluation_output);
+    return output;
   }
 
   /* TODO make this work with new framework */

robo/src/lib.rs

@@ -4,7 +4,7 @@ extern crate itertools;
 extern crate schala_repl;
 
 use itertools::Itertools;
-use schala_repl::{ProgrammingLanguageInterface, EvalOptions, FinishedComputation, UnfinishedComputation};
+use schala_repl::{ProgrammingLanguageInterface, EvalOptions, LanguageOutput};
 
 pub struct Robo {
 }
@@ -155,16 +155,18 @@ impl ProgrammingLanguageInterface for Robo {
     format!("robo")
   }
 
-  fn execute_pipeline(&mut self, input: &str, _eval_options: &EvalOptions) -> FinishedComputation {
-    let output = UnfinishedComputation::default();
+  fn evaluate_in_repl(&mut self, input: &str, _eval_options: &EvalOptions) -> LanguageOutput {
+    let mut output = LanguageOutput::default();
     let tokens = match tokenize(input) {
       Ok(tokens) => tokens,
       Err(e) => {
-        return output.finish(Err(format!("Tokenize error: {:?}", e)));
+        output.add_output(format!("Tokenize error: {:?}", e));
+        return output;
       }
     };
 
-    output.finish(Ok(format!("{:?}", tokens)))
+    output.add_output(format!("{:?}", tokens));
+    output
   }
 }
 

rukka/src/lib.rs

@@ -4,7 +4,7 @@ extern crate itertools;
 extern crate schala_repl;
 
 use itertools::Itertools;
-use schala_repl::{ProgrammingLanguageInterface, EvalOptions, UnfinishedComputation, FinishedComputation};
+use schala_repl::{ProgrammingLanguageInterface, EvalOptions, LanguageOutput};
 use std::iter::Peekable;
 use std::vec::IntoIter;
 use std::str::Chars;
@@ -73,11 +73,12 @@ impl ProgrammingLanguageInterface for Rukka {
     format!("rukka")
   }
 
-  fn execute_pipeline(&mut self, input: &str, _eval_options: &EvalOptions) -> FinishedComputation {
-    let output = UnfinishedComputation::default();
+  fn evaluate_in_repl(&mut self, input: &str, _eval_options: &EvalOptions) -> LanguageOutput {
+    let mut output = LanguageOutput::default();
     let sexps = match read(input) {
       Err(err) => {
-        return output.finish(Err(format!("Error: {}", err)));
+        output.add_output(format!("Error: {}", err));
+        return output;
       },
       Ok(sexps) => sexps
     };
@@ -88,7 +89,8 @@ impl ProgrammingLanguageInterface for Rukka {
         Err(err) => format!("{} Error: {}", i, err),
       }
     }).intersperse(format!("\n")).collect();
-    output.finish(Ok(output_str))
+    output.add_output(output_str);
+    output
   }
 }
 

schala-codegen/Cargo.toml

@@ -4,9 +4,9 @@ version = "0.1.0"
 authors = ["greg <greg.shuflin@protonmail.com>"]
 
 [dependencies]
+quote = "0.5.2"
 syn = { version = "0.13.1", features = ["full", "extra-traits"] }
-quote = "0.5"
-schala-repl = { path = "../schala-repl" }
+
 
 [lib]
 proc-macro = true

schala-codegen/src/lib.rs

@@ -1,103 +1,95 @@
-#![feature(trace_macros)]
 #![feature(proc_macro)]
 extern crate proc_macro;
 #[macro_use]
-extern crate quote;
 extern crate syn;
-
-extern crate schala_repl;
+#[macro_use]
+extern crate quote;
 
 use proc_macro::TokenStream;
-use syn::{Ident, Attribute, DeriveInput};
+use syn::{Expr, Lit, ExprLit};
+use syn::punctuated::Punctuated;
+use syn::synom::Synom;
 
-fn extract_attribute_arg_by_name(name: &str, attrs: &Vec<Attribute>) -> Option<String> {
-  use syn::{Meta, Lit, MetaNameValue};
-  attrs.iter().map(|attr| attr.interpret_meta()).find(|meta| {
-    match meta {
-      &Some(Meta::NameValue(MetaNameValue { ident, .. })) if ident.as_ref() == name => true,
-      _ => false
-    }
-  }).and_then(|meta| {
-    match meta {
-      Some(Meta::NameValue(MetaNameValue { lit: Lit::Str(litstr), .. })) => Some(litstr.value()),
-      _ => None,
-    }
-  })
+
+fn get_string_args(input: Expr) -> Vec<String> {
+  let mut contained_strings = Vec::new();
+  match input {
+    Expr::Array(array) => {
+      for item in array.elems {
+        if let Expr::Lit(ExprLit { lit: Lit::Str(s), ..}) = item {
+          contained_strings.push(s.value());
+        } else {
+          panic!("Non-string-literal input to compiler_pass_sequence");
+        }
+      }
+    },
+    _ => panic!("Non-array input to compiler_pass_sequence"),
+  }
+  contained_strings
 }
 
-fn extract_attribute_list(name: &str, attrs: &Vec<Attribute>) -> Option<Vec<(Ident, Option<Vec<Ident>>)>> {
-  use syn::{Meta, MetaList, NestedMeta};
-  attrs.iter().find(|attr| {
-    match attr.path.segments.iter().nth(0) {
-      Some(segment) if segment.ident.as_ref() == name => true,
-      _ => false
+#[proc_macro]
+pub fn compiler_pass_sequence(input: TokenStream) -> TokenStream {
+  /*
+  for token_tree in input {
+    //println!("ITEM: {:?}", token_tree.kind);
+    match token_tree.kind {
+      TokenNode::Literal(l) => println!("{:?}", l),
+      _ => ()
     }
-  }).and_then(|attr| {
-    match attr.interpret_meta() {
-      Some(Meta::List(MetaList { nested, .. })) => {
-        Some(nested.iter().map(|nested_meta| match nested_meta {
-          &NestedMeta::Meta(Meta::Word(ident)) => (ident, None),
-          &NestedMeta::Meta(Meta::List(MetaList { ident, nested: ref nested2, .. })) => {
-            let own_args = nested2.iter().map(|nested_meta2| match nested_meta2 {
-              &NestedMeta::Meta(Meta::Word(ident)) => ident,
-              _ => panic!("Bad format for doubly-nested attribute list")
-            }).collect();
-            (ident, Some(own_args))
-          },
-          _ => panic!("Bad format for nested list")
-        }).collect())
-      },
-      _ => panic!("{} must be a comma-delimited list surrounded by parens", name)
-    }
-  })
-}
+  }
+  */
 
-#[proc_macro_derive(ProgrammingLanguageInterface, attributes(LanguageName, SourceFileExtension, PipelineSteps))]
-pub fn derive_programming_language_interface(input: TokenStream) -> TokenStream {
-  use schala_repl::PassDescriptor;
-  let ast: DeriveInput = syn::parse(input).unwrap();
-  let name = &ast.ident;
-  let attrs = &ast.attrs;
+  let input: Expr = syn::parse(input).unwrap();
+  let stages = get_string_args(input);
+  let from_macro = format!("{:?}", stages);
 
-  let language_name: String = extract_attribute_arg_by_name("LanguageName", attrs).expect("LanguageName is required");
-  let file_ext = extract_attribute_arg_by_name("SourceFileExtension", attrs).expect("SourceFileExtension is required");
-  let passes = extract_attribute_list("PipelineSteps", attrs).expect("PipelineSteps are required");
-  let pass_idents = passes.iter().map(|x| x.0);
-
-  //let pass_names: Vec<String> = passes.iter().map(|pass| pass.0.to_string()).collect();
-  let pass_descriptors = passes.iter().map(|pass| {
-    let name = pass.0.to_string();
-    let opts: Vec<String> = match &pass.1 {
-      None => vec![],
-      Some(opts) => opts.iter().map(|o| o.to_string()).collect(),
-    };
-
-    quote! {
-      PassDescriptor {
-        name: #name.to_string(),
-        debug_options: vec![#(format!(#opts)),*]
-      }
-    }
-  });
-
-  let tokens = quote! {
-    use schala_repl::PassDescriptor;
-    impl ProgrammingLanguageInterface for #name {
-      fn get_language_name(&self) -> String {
-        #language_name.to_string()
-      }
-      fn get_source_file_suffix(&self) -> String {
-        #file_ext.to_string()
-      }
-      fn execute_pipeline(&mut self, input: &str, options: &EvalOptions) -> FinishedComputation {
-        let mut chain = pass_chain![self, options; #(#pass_idents),* ];
-        chain(input)
-      }
-      fn get_passes(&self) -> Vec<PassDescriptor> {
-        vec![ #(#pass_descriptors),* ]
-        //vec![ #(PassDescriptor { name: #pass_names.to_string(), debug_options: vec![] }),* ]
-      }
+  let output = quote! {
+    fn new_execute(&mut self, input: &str, _options: &EvalOptions) -> FinishedComputation {
+      let evaluation = UnfinishedComputation::default();
+      evaluation.output(Err(#from_macro.to_string()))
     }
   };
-  tokens.into()
+  output.into()
 }
+
+/* #[compiler_pass(<name of pass>*/
+#[proc_macro_attribute]
+pub fn compiler_pass(metadata: TokenStream, function: TokenStream) -> TokenStream {
+  //println!("FROM MACRO: {}", function);
+  println!("Compiler pass metadata: {}", metadata);
+  function
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        assert_eq!(2 + 2, 4);
+    }
+}
+
+
+/* in Rocket
+ *
+
+ #[get("/")]
+ fn hi() -> &'static str {
+ "hello"
+ }
+
+ GETS MAPPED TO:
+
+ static hi_info = RouteInfo {
+  name: "hi",
+  method: Method::Get,
+  path: "/",
+  handler: hi_route,
+  }
+
+  fn hi_route(req: &Request) -> Outcome {
+  let responder = hi();
+  Outcome::from(req, responder);
+  }
+
+ */

schala-lang/src/ast.rs

@@ -1,176 +0,0 @@
-use std::rc::Rc;
-
-use builtin::{BinOp, PrefixOp};
-
-#[derive(Debug, PartialEq)]
-pub struct AST(pub Vec<Statement>);
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum Statement {
-  ExpressionStatement(Expression),
-  Declaration(Declaration),
-}
-
-pub type Block = Vec<Statement>;
-
-pub type ParamName = Rc<String>;
-pub type InterfaceName = Rc<String>; //should be a singleton I think??
-pub type FormalParam = (ParamName, Option<TypeName>);
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum Declaration {
-  FuncSig(Signature),
-  FuncDecl(Signature, Block),
-  TypeDecl {
-    name: TypeSingletonName,
-    body: TypeBody,
-    mutable: bool
-  },
-  TypeAlias(Rc<String>, Rc<String>), //should have TypeSingletonName in it, or maybe just String, not sure
-  Binding {
-    name: Rc<String>,
-    constant: bool,
-    expr: Expression,
-  },
-  Impl {
-    type_name: TypeName,
-    interface_name: Option<InterfaceName>,
-    block: Vec<Declaration>,
-  },
-  Interface {
-    name: Rc<String>,
-    signatures: Vec<Signature>
-  }
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct Signature {
-  pub name: Rc<String>,
-  pub params: Vec<FormalParam>,
-  pub type_anno: Option<TypeName>,
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct TypeBody(pub Vec<Variant>);
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum Variant {
-  UnitStruct(Rc<String>),
-  TupleStruct(Rc<String>, Vec<TypeName>),
-  Record(Rc<String>, Vec<(Rc<String>, TypeName)>),
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct Expression(pub ExpressionType, pub Option<TypeName>);
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum TypeName {
-  Tuple(Vec<TypeName>),
-  Singleton(TypeSingletonName)
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct TypeSingletonName {
-  pub name: Rc<String>,
-  pub params: Vec<TypeName>,
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum ExpressionType {
-  NatLiteral(u64),
-  FloatLiteral(f64),
-  StringLiteral(Rc<String>),
-  BoolLiteral(bool),
-  BinExp(BinOp, Box<Expression>, Box<Expression>),
-  PrefixExp(PrefixOp, Box<Expression>),
-  TupleLiteral(Vec<Expression>),
-  Value(Rc<String>),
-  NamedStruct {
-    name: Rc<String>,
-    fields: Vec<(Rc<String>, Expression)>,
-  },
-  Call {
-    f: Box<Expression>,
-    arguments: Vec<Expression>,
-  },
-  Index {
-    indexee: Box<Expression>,
-    indexers: Vec<Expression>,
-  },
-  IfExpression {
-    discriminator: Box<Discriminator>,
-    body: Box<IfExpressionBody>,
-  },
-  WhileExpression {
-    condition: Option<Box<Expression>>,
-    body: Block,
-  },
-  ForExpression {
-    enumerators: Vec<Enumerator>,
-    body: Box<ForBody>,
-  },
-  Lambda {
-    params: Vec<FormalParam>,
-    body: Block,
-  },
-  ListLiteral(Vec<Expression>),
-}
-#[derive(Debug, PartialEq, Clone)]
-pub enum Discriminator {
-  Simple(Expression),
-  BinOp(Expression, BinOp)
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum IfExpressionBody {
-  SimpleConditional(Block, Option<Block>),
-  SimplePatternMatch(Pattern, Block, Option<Block>),
-  GuardList(Vec<GuardArm>)
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct GuardArm {
-  pub guard: Guard,
-  pub body: Block,
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum Guard {
-  Pat(Pattern),
-  HalfExpr(HalfExpr)
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct HalfExpr {
-  pub op: Option<BinOp>,
-  pub expr: ExpressionType,
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum Pattern {
-  Ignored,
-  TuplePattern(Vec<Pattern>),
-  Literal(PatternLiteral),
-  TupleStruct(Rc<String>, Vec<Pattern>),
-  Record(Rc<String>, Vec<(Rc<String>, Pattern)>),
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum PatternLiteral {
-  NumPattern(ExpressionType),
-  StringPattern(Rc<String>),
-  BoolPattern(bool),
-  VarPattern(Rc<String>)
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct Enumerator {
-  pub id: Rc<String>,
-  pub generator: Expression,
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum ForBody {
-  MonadicReturn(Expression),
-  StatementBlock(Block),
-}

schala-lang/src/builtin.rs

@@ -1,31 +1,8 @@
 use std::rc::Rc;
 use std::collections::HashMap;
-use std::fmt;
 
-use self::Type::*; use self::TConstOld::*;
-
-
-//TODO get rid of these types and replace them with the right MonoType or whatever ones later
-#[derive(Debug, PartialEq, Clone)]
-pub enum Type {
-  Const(TConstOld),
-  Func(Box<Type>, Box<Type>),
-}
-
-#[derive(Debug, PartialEq, Clone)]
-pub enum TConstOld {
-  Nat,
-  Int,
-  Float,
-  StringT,
-  Bool,
-}
-
-impl fmt::Display for Type {
-  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-    write!(f, "{:?}", self)
-  }
-}
+use typechecking::{Type, TypeResult, TConst};
+use self::Type::*; use self::TConst::*;
 
 #[derive(Debug, PartialEq, Clone)]
 pub struct BinOp {
@@ -39,7 +16,7 @@ impl BinOp {
   pub fn sigil(&self) -> &Rc<String> {
     &self.sigil
   }
-  pub fn get_type(&self) -> Result<Type, String> {
+  pub fn get_type(&self) -> TypeResult<Type> {
     let s = self.sigil.as_str();
     BINOPS.get(s).map(|x| x.0.clone()).ok_or(format!("Binop {} not found", s))
   }
@@ -67,7 +44,7 @@ impl PrefixOp {
   pub fn is_prefix(op: &str) -> bool {
     PREFIX_OPS.get(op).is_some()
   }
-  pub fn get_type(&self) -> Result<Type, String> {
+  pub fn get_type(&self) -> TypeResult<Type> {
     let s = self.sigil.as_str();
     PREFIX_OPS.get(s).map(|x| x.0.clone()).ok_or(format!("Prefix op {} not found", s))
   }
@@ -86,15 +63,15 @@ lazy_static! {
 lazy_static! {
   static ref BINOPS: HashMap<&'static str, (Type, (), i32)> =
     hashmap! {
-      "+" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 10),
-      "-" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 10),
-      "*" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      "/" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Float))))), (), 20),
-      "//" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20), //TODO change this to `quot`
-      "%" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "+" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 10),
+      "-" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 10),
+      "*" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 20),
+      "/" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Float))))), (), 20),
+      "//" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 20), //TODO change this to `quot`
+      "%" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 20),
       "++" => (Func(bx!(Const(StringT)), bx!(Func(bx!(Const(StringT)), bx!(Const(StringT))))), (), 30),
-      "^" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      "&" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
-      "|" => (Func(bx!(Const(Nat)), bx!(Func(bx!(Const(Nat)), bx!(Const(Nat))))), (), 20),
+      "^" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 20),
+      "&" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 20),
+      "|" => (Func(bx!(Const(Int)), bx!(Func(bx!(Const(Int)), bx!(Const(Int))))), (), 20),
     };
 }

schala-lang/src/eval.rs

@@ -1,375 +1,317 @@
-use std::cell::RefCell;
+use std::collections::HashMap;
 use std::rc::Rc;
 use std::fmt::Write;
-use std::io;
 
 use itertools::Itertools;
 
-use util::StateStack;
-use reduced_ast::{ReducedAST, Stmt, Expr, Lit, Func};
-use symbol_table::{SymbolSpec, Symbol, SymbolTable};
+use parsing::{AST, Statement, Declaration, Expression, Variant, ExpressionType};
+use builtin::{BinOp, PrefixOp};
 
 pub struct State<'a> {
-  values: StateStack<'a, Rc<String>, ValueEntry>,
-  symbol_table_handle: Rc<RefCell<SymbolTable>>,
-}
-
-macro_rules! builtin_binding {
-  ($name:expr, $values:expr) => {
-    $values.insert(Rc::new(format!($name)), ValueEntry::Binding { constant: true, val: Expr::Func(Func::BuiltIn(Rc::new(format!($name)))) });
-  }
+  parent_frame: Option<&'a State<'a>>,
+  values: HashMap<Rc<String>, ValueEntry>,
 }
 
 impl<'a> State<'a> {
-  pub fn new(symbol_table_handle: Rc<RefCell<SymbolTable>>) -> State<'a> {
-    let mut values = StateStack::new(Some(format!("global")));
-    builtin_binding!("print", values);
-    builtin_binding!("println", values);
-    builtin_binding!("getline", values);
-    State { values, symbol_table_handle }
-  }
 
-  pub fn debug_print(&self) -> String {
-    format!("Values: {:?}", self.values)
+  fn insert(&mut self, name: Rc<String>, value: ValueEntry) {
+    self.values.insert(name, value);
+  }
+  fn lookup(&self, name: &Rc<String>) -> Option<&ValueEntry> {
+    match (self.values.get(name), self.parent_frame) {
+      (None, None) => None,
+      (None, Some(parent)) => parent.lookup(name),
+      (Some(value), _) => Some(value),
+    }
   }
 }
 
 #[derive(Debug)]
 enum ValueEntry {
   Binding {
-    constant: bool,
-    val: /*FullyEvaluatedExpr*/ Expr,
+    val: FullyEvaluatedExpr,
+  },
+  Function {
+    param_names: Vec<Rc<String>>,
+    body: Vec<Statement>,
   }
 }
 
 type EvalResult<T> = Result<T, String>;
 
+#[derive(Debug, PartialEq, Clone)]
+enum FullyEvaluatedExpr {
+  UnsignedInt(u64),
+  SignedInt(i64),
+  Float(f64),
+  Str(String),
+  Bool(bool),
+  FuncLit(Rc<String>),
+  Custom {
+    string_rep: Rc<String>,
+  },
+  Tuple(Vec<FullyEvaluatedExpr>),
+  List(Vec<FullyEvaluatedExpr>)
+}
 
-impl Expr {
-  fn to_repl(&self) -> String {
-    use self::Lit::*;
-    use self::Func::*;
-    fn paren_wrapped_vec(exprs: &Vec<Expr>) -> String {
-      let mut buf = String::new();
-      write!(buf, "(").unwrap();
-      for term in exprs.iter().map(|e| Some(e)).intersperse(None) {
-        match term {
-          Some(e) => write!(buf, "{}", e.to_repl()).unwrap(),
-          None => write!(buf, ", ").unwrap(),
-        };
-      }
-      write!(buf, ")").unwrap();
-      buf
-    }
-
+impl FullyEvaluatedExpr {
+  fn to_string(&self) -> String {
+    use self::FullyEvaluatedExpr::*;
     match self {
-      Expr::Lit(ref l) => match l {
-        Nat(n) => format!("{}", n),
-        Int(i) => format!("{}", i),
-        Float(f) => format!("{}", f),
-        Bool(b) => format!("{}", b),
-        StringLit(s) => format!("\"{}\"", s),
-        Custom(name, args) if args.len() == 0 => format!("{}", name),
-        Custom(name, args) => format!("{}{}", name, paren_wrapped_vec(args)),
+      &UnsignedInt(ref n) => format!("{}", n),
+      &SignedInt(ref n) => format!("{}", n),
+      &Float(ref f) => format!("{}", f),
+      &Str(ref s) => format!("\"{}\"", s),
+      &Bool(ref b) => format!("{}", b),
+      &Custom { ref string_rep } => format!("{}", string_rep),
+      &Tuple(ref items) => {
+        let mut buf = String::new();
+        write!(buf, "(").unwrap();
+        for term in items.iter().map(|e| Some(e)).intersperse(None) {
+          match term {
+            Some(e) => write!(buf, "{}", e.to_string()).unwrap(),
+            None => write!(buf, ", ").unwrap(),
+          };
+        }
+        write!(buf, ")").unwrap();
+        buf
       },
-      Expr::Func(f) => match f {
-        BuiltIn(name) => format!("<built-in function {}>", name),
-        UserDefined { name: None, .. } => format!("<function>"),
-        UserDefined { name: Some(name), .. } => format!("<function {}>", name),
-      },
-      Expr::Constructor { name } => format!("<constructor {}>", name),
-      Expr::Tuple(exprs) => paren_wrapped_vec(exprs),
-      _ => format!("{:?}", self),
+      &FuncLit(ref name) => format!("<function {}>", name),
+      &List(ref items) => {
+        let mut buf = String::new();
+        write!(buf, "[").unwrap();
+        for term in items.iter().map(|e| Some(e)).intersperse(None) {
+          match term {
+            Some(e) => write!(buf, "{}", e.to_string()).unwrap(),
+            None => write!(buf, ", ").unwrap()
+          }
+        }
+        write!(buf, "]").unwrap();
+        buf
+      }
     }
   }
 }
 
 impl<'a> State<'a> {
-  pub fn evaluate(&mut self, ast: ReducedAST, repl: bool) -> Vec<Result<String, String>> {
+  pub fn new() -> State<'a> {
+    State { parent_frame: None, values: HashMap::new() }
+  }
+
+  pub fn new_with_parent(parent: &'a State<'a>) -> State<'a> {
+    State { parent_frame: Some(parent), values: HashMap::new() }
+  }
+
+  pub fn evaluate(&mut self, ast: AST) -> Vec<Result<String, String>> {
     let mut acc = vec![];
-
-    // handle prebindings
-    for statement in ast.0.iter() {
-      self.prebinding(statement);
-    }
-
     for statement in ast.0 {
-      match self.statement(statement) {
-        Ok(Some(ref output)) if repl => acc.push(Ok(output.to_repl())),
-        Ok(_) => (),
+      match self.eval_statement(statement) {
+        Ok(output) => {
+          if let Some(fully_evaluated) = output {
+            acc.push(Ok(fully_evaluated.to_string()));
+          }
+        },
         Err(error) => {
-          acc.push(Err(format!("Runtime error: {}", error)));
+          acc.push(Err(format!("Eval error: {}", error)));
           return acc;
         },
       }
     }
     acc
   }
+}
 
-  fn prebinding(&mut self, stmt: &Stmt) {
-    match stmt {
-      Stmt::PreBinding { name, func } => {
-        let v_entry = ValueEntry::Binding { constant: true, val: Expr::Func(func.clone()) };
-        self.values.insert(name.clone(), v_entry);
-      },
-      Stmt::Expr(_expr) => {
-        //TODO have this support things like nested function defs
-
-      },
-      _ => ()
-    }
-  }
-
-  fn statement(&mut self, stmt: Stmt) -> EvalResult<Option<Expr>> {
-    match stmt {
-      Stmt::Binding { name, constant, expr } => {
-        let val = self.expression(expr)?;
-        self.values.insert(name.clone(), ValueEntry::Binding { constant, val });
-        Ok(None)
-      },
-      Stmt::Expr(expr) => Ok(Some(self.expression(expr)?)),
-      Stmt::PreBinding {..} | Stmt::Noop => Ok(None),
-    }
-  }
-
-  fn block(&mut self, stmts: Vec<Stmt>) -> EvalResult<Expr> {
-    let mut ret = None;
-    for stmt in stmts {
-      ret = self.statement(stmt)?;
-    }
-    Ok(ret.unwrap_or(Expr::Unit))
-  }
-
-  fn expression(&mut self, expr: Expr) -> EvalResult<Expr> {
-    use self::Expr::*;
-    match expr {
-      literal @ Lit(_) => Ok(literal),
-      Call { box f, args } => {
-        match self.expression(f)? {
-          Constructor {name} => self.apply_data_constructor(name, args),
-          Func(f) => self.apply_function(f, args),
-          other => return Err(format!("Tried to call {:?} which is not a function or data constructor", other)),
-        }
-      },
-      Val(v) => self.value(v),
-      constr @ Constructor { .. } => Ok(constr),
-      func @ Func(_) => Ok(func),
-      Tuple(exprs) => Ok(Tuple(exprs.into_iter().map(|expr| self.expression(expr)).collect::<Result<Vec<Expr>,_>>()?)),
-      Conditional { box cond, then_clause, else_clause } => self.conditional(cond, then_clause, else_clause),
-      Assign { box val, box expr } => {
-        let name = match val  {
-          Expr::Val(name) => name,
-          _ => return Err(format!("Trying to assign to a non-value")),
-        };
-
-        let constant = match self.values.lookup(&name) {
-          None => return Err(format!("{} is undefined", name)),
-          Some(ValueEntry::Binding { constant, .. }) => constant.clone(),
-        };
-        if constant {
-          return Err(format!("trying to update {}, a non-mutable binding", name));
-        }
-        let val = self.expression(expr)?;
-        self.values.insert(name.clone(), ValueEntry::Binding { constant: false, val });
-        Ok(Expr::Unit)
-      },
-      e => Err(format!("Expr {:?} eval not implemented", e))
-    }
-  }
-
-  fn apply_data_constructor(&mut self, name: Rc<String>, args: Vec<Expr>) -> EvalResult<Expr> {
-    {
-      let symbol_table = self.symbol_table_handle.borrow();
-      match symbol_table.values.get(&name) {
-        Some(Symbol { spec: SymbolSpec::DataConstructor { type_name, type_args }, name }) => {
-          if args.len() != type_args.len() {
-            return Err(format!("Data constructor {} requires {} args", name, type_args.len()));
-          }
-          ()
-        },
-        _ => return Err(format!("Bad symbol {}", name))
-      }
-    }
-    let evaled_args = args.into_iter().map(|expr| self.expression(expr)).collect::<Result<Vec<Expr>,_>>()?;
-    //let evaled_args = vec![];
-    Ok(Expr::Lit(self::Lit::Custom(name.clone(), evaled_args)))
-  }
-
-  fn apply_function(&mut self, f: Func, args: Vec<Expr>) -> EvalResult<Expr> {
-    match f {
-      Func::BuiltIn(sigil) => self.apply_builtin(sigil, args),
-      Func::UserDefined { params, body, name } => {
-
-        if params.len() != args.len() {
-          return Err(format!("calling a {}-argument function with {} args", params.len(), args.len()))
-        }
-        let mut func_state = State {
-          values: self.values.new_frame(name.map(|n| format!("{}", n))),
-          symbol_table_handle: self.symbol_table_handle.clone(),
-        };
-        for (param, val) in params.into_iter().zip(args.into_iter()) {
-          let val = func_state.expression(val)?;
-          func_state.values.insert(param, ValueEntry::Binding { constant: true, val });
-        }
-        // TODO figure out function return semantics
-        func_state.block(body)
-      }
-    }
-  }
-
-  fn apply_builtin(&mut self, name: Rc<String>, args: Vec<Expr>) -> EvalResult<Expr> {
-    use self::Expr::*;
-    use self::Lit::*;
-    let evaled_args: Result<Vec<Expr>, String> = args.into_iter().map(|arg| self.expression(arg)).collect();
-    let evaled_args = evaled_args?;
-
-    Ok(match (name.as_str(), evaled_args.as_slice()) {
-      /* binops */
-      ("+", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l + r)),
-      ("++", &[Lit(StringLit(ref s1)), Lit(StringLit(ref s2))]) => Lit(StringLit(Rc::new(format!("{}{}", s1, s2)))),
-      ("-", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l - r)),
-      ("*", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l * r)),
-      ("/", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Float((l as f64)/ (r as f64))),
-      ("//", &[Lit(Nat(l)), Lit(Nat(r))]) => if r == 0 {
-        return Err(format!("divide by zero"));
-      } else {
-        Lit(Nat(l / r))
-      },
-      ("%", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l % r)),
-      ("^", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l ^ r)),
-      ("&", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l & r)),
-      ("|", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l | r)),
-
-      ("==", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Bool(l == r)),
-      ("==", &[Lit(Int(l)), Lit(Int(r))]) => Lit(Bool(l == r)),
-      ("==", &[Lit(Float(l)), Lit(Float(r))]) => Lit(Bool(l == r)),
-      ("==", &[Lit(Bool(l)), Lit(Bool(r))]) => Lit(Bool(l == r)),
-      ("==", &[Lit(StringLit(ref l)), Lit(StringLit(ref r))]) => Lit(Bool(l == r)),
-
-      /* prefix ops */
-      ("!", &[Lit(Bool(true))]) => Lit(Bool(false)),
-      ("!", &[Lit(Bool(false))]) => Lit(Bool(true)),
-      ("-", &[Lit(Nat(n))]) => Lit(Int(-1*(n as i64))),
-      ("-", &[Lit(Int(n))]) => Lit(Int(-1*(n as i64))),
-      ("+", &[Lit(Int(n))]) => Lit(Int(n)),
-      ("+", &[Lit(Nat(n))]) => Lit(Nat(n)),
-
-
-      /* builtin functions */
-      ("print", &[ref anything]) => {
-        print!("{}", anything.to_repl());
-        Expr::Unit
-      },
-      ("println", &[ref anything]) => {
-        println!("{}", anything.to_repl());
-        Expr::Unit
-      },
-      ("getline", &[]) => {
-        let mut buf = String::new();
-        io::stdin().read_line(&mut buf).expect("Error readling line in 'getline'");
-        Lit(StringLit(Rc::new(buf.trim().to_string())))
-      },
-      (x, args) => return Err(format!("bad or unimplemented builtin {:?} | {:?}", x, args)),
+impl<'a> State<'a> {
+  fn eval_statement(&mut self, statement: Statement) -> EvalResult<Option<FullyEvaluatedExpr>> {
+    Ok(match statement {
+      Statement::ExpressionStatement(expr) => Some(self.eval_expr(expr)?),
+      Statement::Declaration(decl) => { self.eval_decl(decl)?; None }
     })
   }
 
-  fn conditional(&mut self, cond: Expr, then_clause: Vec<Stmt>, else_clause: Vec<Stmt>) -> EvalResult<Expr> {
-    let cond = self.expression(cond)?;
-    Ok(match cond {
-      Expr::Lit(Lit::Bool(true)) =>  self.block(then_clause)?,
-      Expr::Lit(Lit::Bool(false)) => self.block(else_clause)?,
-      _ => return Err(format!("Conditional with non-boolean condition"))
-    })
+  fn eval_decl(&mut self, decl: Declaration) -> EvalResult<()> {
+    use self::Declaration::*;
+    use self::Variant::*;
+
+    match decl {
+      FuncDecl(signature, statements) => {
+        let name = signature.name;
+        let param_names: Vec<Rc<String>> = signature.params.iter().map(|fp| fp.0.clone()).collect();
+        self.insert(name, ValueEntry::Function { body: statements.clone(), param_names });
+      },
+      TypeDecl(_name, body) => {
+        for variant in body.0.iter() {
+          match variant {
+            &UnitStruct(ref name) => self.insert(name.clone(),
+              ValueEntry::Binding { val: FullyEvaluatedExpr::Custom { string_rep: name.clone() } }),
+            &TupleStruct(ref _name, ref _args) =>  unimplemented!(),
+            &Record(ref _name, ref _fields) => unimplemented!(),
+          };
+        }
+      },
+      Binding { name, expr, ..} => {
+        let val = self.eval_expr(expr)?;
+        self.insert(name.clone(), ValueEntry::Binding { val });
+      },
+      _ => return Err(format!("Declaration evaluation not yet implemented"))
+    }
+    Ok(())
   }
 
-  fn value(&mut self, name: Rc<String>) -> EvalResult<Expr> {
-    use self::ValueEntry::*;
-    use self::Func::*;
-    //TODO add a layer of indirection here to talk to the symbol table first, and only then look up
-    //in the values table
+  fn eval_expr(&mut self, expr: Expression) -> EvalResult<FullyEvaluatedExpr> {
+    use self::ExpressionType::*;
+    use self::FullyEvaluatedExpr::*;
 
-    let symbol_table = self.symbol_table_handle.borrow();
-    let value = symbol_table.values.get(&name);
-    Ok(match value {
-      Some(Symbol { name, spec }) => match spec {
-        SymbolSpec::DataConstructor { type_name, type_args } => {
-          if type_args.len() == 0 {
-            Expr::Lit(Lit::Custom(name.clone(), vec![]))
-          } else {
-            return Err(format!("This data constructor thing not done"))
+    let expr_type = expr.0;
+    match expr_type {
+      IntLiteral(n) => Ok(UnsignedInt(n)),
+      FloatLiteral(f) => Ok(Float(f)),
+      StringLiteral(s) => Ok(Str(s.to_string())),
+      BoolLiteral(b) => Ok(Bool(b)),
+      PrefixExp(op, expr) => self.eval_prefix_exp(op, expr),
+      BinExp(op, lhs, rhs) => self.eval_binexp(op, lhs, rhs),
+      Value(name) => self.eval_value(name),
+      TupleLiteral(expressions) => {
+        let mut evals = Vec::new();
+        for expr in expressions {
+          match self.eval_expr(expr) {
+            Ok(fully_evaluated) => evals.push(fully_evaluated),
+            error => return error,
           }
-        },
-        SymbolSpec::Func(_) => match self.values.lookup(&name) {
-          Some(Binding { val: Expr::Func(UserDefined { name, params, body }), .. }) => {
-            Expr::Func(UserDefined { name: name.clone(), params: params.clone(), body: body.clone() })
+        }
+        Ok(Tuple(evals))
+      }
+      Call { f, arguments } => {
+        let mut evaled_arguments = Vec::new();
+        for arg in arguments.into_iter() {
+          evaled_arguments.push(self.eval_expr(arg)?);
+        }
+        self.eval_application(*f, evaled_arguments)
+      },
+      Index { box indexee, indexers } => {
+        let evaled = self.eval_expr(indexee)?;
+        match evaled {
+          Tuple(mut exprs) => {
+            let len = indexers.len();
+            if len == 1 {
+              let idx = indexers.into_iter().nth(0).unwrap();
+              match self.eval_expr(idx)? {
+                UnsignedInt(n) if (n as usize) < exprs.len() => Ok(exprs.drain(n as usize..).next().unwrap()),
+                UnsignedInt(n) => Err(format!("Index {} out of range", n)),
+                other => Err(format!("{:?} is not an unsigned integer", other)),
+              }
+            } else {
+              Err(format!("Tuple index must be one integer"))
+            }
           },
-          _ => unreachable!(),
-        },
+          _ => Err(format!("Bad index expression"))
+        }
       },
-      /* see if it's an ordinary variable TODO make variables go in symbol table */
-      None => match self.values.lookup(&name) {
-        Some(Binding { val, .. }) => val.clone(),
-        None => return Err(format!("Couldn't find value {}", name)),
+      ListLiteral(items) => Ok(List(items.into_iter().map(|item| self.eval_expr(item)).collect::<Result<Vec<_>,_>>()?)),
+      x => Err(format!("Unimplemented thing {:?}", x)),
+    }
+  }
+
+  fn eval_application(&mut self, f: Expression, arguments: Vec<FullyEvaluatedExpr>) -> EvalResult<FullyEvaluatedExpr> {
+    use self::ExpressionType::*;
+    match f {
+      Expression(Value(ref identifier), _) if self.is_builtin(identifier) =>  self.eval_builtin(identifier, arguments),
+      Expression(Value(identifier), _) => {
+        match self.lookup(&identifier) {
+          Some(&ValueEntry::Function { ref body, ref param_names }) => {
+            if arguments.len() != param_names.len() {
+              return Err(format!("Wrong number of arguments for the function"));
+            }
+            let mut new_state = State::new_with_parent(self);
+            let sub_ast = body.clone();
+            for (param, val) in param_names.iter().zip(arguments.into_iter()) {
+              new_state.insert(param.clone(), ValueEntry::Binding { val });
+            }
+            let mut ret: Option<FullyEvaluatedExpr> = None;
+            for statement in sub_ast.into_iter() {
+              ret = new_state.eval_statement(statement)?;
+            }
+            Ok(ret.unwrap_or(FullyEvaluatedExpr::Custom { string_rep: Rc::new("()".to_string()) }))
+          },
+          _ => Err(format!("Function {} not found", identifier)),
+        }
+      },
+      x => Err(format!("Trying to apply {:?} which is not a function", x)),
+    }
+  }
+  fn is_builtin(&self, name: &Rc<String>) -> bool {
+    match &name.as_ref()[..] {
+      "print" | "println" => true,
+      _ => false
+    }
+  }
+  fn eval_builtin(&mut self, name: &Rc<String>, args: Vec<FullyEvaluatedExpr>) -> EvalResult<FullyEvaluatedExpr> {
+    use self::FullyEvaluatedExpr::*;
+    match &name.as_ref()[..] {
+      "print" => {
+        for arg in args {
+          print!("{}", arg.to_string());
+        }
+        Ok(Tuple(vec![]))
+      },
+      "println" => {
+        for arg in args {
+          println!("{}", arg.to_string());
+        }
+        Ok(Tuple(vec![]))
+      },
+      _ => unreachable!()
+    }
+  }
+  fn eval_value(&mut self, name: Rc<String>) -> EvalResult<FullyEvaluatedExpr> {
+    use self::ValueEntry::*;
+    match self.lookup(&name) {
+      None => return Err(format!("Value {} not found", *name)),
+      Some(lookup) => match lookup {
+        &Binding { ref val } => Ok(val.clone()),
+        &Function { .. } =>  Ok(FullyEvaluatedExpr::FuncLit(name.clone()))
       }
+    }
+  }
+
+  fn eval_binexp(&mut self, op: BinOp, lhs: Box<Expression>, rhs: Box<Expression>) -> EvalResult<FullyEvaluatedExpr> {
+    use self::FullyEvaluatedExpr::*;
+    let evaled_lhs = self.eval_expr(*lhs)?;
+    let evaled_rhs = self.eval_expr(*rhs)?;
+    let sigil = op.sigil();
+    //let sigil: &str = op.sigil().as_ref().as_str();
+    Ok(match (sigil.as_str(), evaled_lhs, evaled_rhs) {
+      ("+", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l + r),
+      ("++", Str(s1), Str(s2)) => Str(format!("{}{}", s1, s2)),
+      ("-", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l - r),
+      ("*", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l * r),
+      ("/", UnsignedInt(l), UnsignedInt(r)) => Float((l as f64)/ (r as f64)),
+      ("//", UnsignedInt(l), UnsignedInt(r)) => if r == 0 {
+        return Err(format!("Runtime error: divide by zero"));
+      } else {
+        UnsignedInt(l / r)
+      },
+      ("%", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l % r),
+      ("^", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l ^ r),
+      ("&", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l & r),
+      ("|", UnsignedInt(l), UnsignedInt(r)) => UnsignedInt(l | r),
+      _ => return Err(format!("Runtime error: not yet implemented")),
+    })
+  }
+
+  fn eval_prefix_exp(&mut self, op: PrefixOp, expr: Box<Expression>) -> EvalResult<FullyEvaluatedExpr> {
+    use self::FullyEvaluatedExpr::*;
+    let evaled_expr = self.eval_expr(*expr)?;
+    let sigil = op.sigil();
+
+    Ok(match (sigil.as_str(), evaled_expr) {
+      ("!", Bool(true)) => Bool(false),
+      ("!", Bool(false)) => Bool(true),
+      ("-", UnsignedInt(n)) => SignedInt(-1*(n as i64)),
+      ("-", SignedInt(n)) => SignedInt(-1*(n as i64)),
+      ("+", SignedInt(n)) => SignedInt(n),
+      ("+", UnsignedInt(n)) => UnsignedInt(n),
+      _ => return Err(format!("Runtime error: not yet implemented")),
     })
   }
 }
-
-#[cfg(test)]
-mod eval_tests {
-  use std::cell::RefCell;
-  use std::rc::Rc;
-  use symbol_table::SymbolTable;
-  use tokenizing::tokenize;
-  use parsing::parse;
-  use eval::State;
-
-  macro_rules! fresh_env {
-    ($string:expr, $correct:expr) => {
-      let symbol_table = Rc::new(RefCell::new(SymbolTable::new()));
-      let mut state = State::new(symbol_table);
-      let ast = parse(tokenize($string)).0.unwrap();
-      state.symbol_table_handle.borrow_mut().add_top_level_symbols(&ast);
-      let reduced = ast.reduce(&state.symbol_table_handle.borrow());
-      let all_output = state.evaluate(reduced, true);
-      let ref output = all_output.last().unwrap();
-      assert_eq!(**output, Ok($correct.to_string()));
-    }
-  }
-
-  #[test]
-  fn test_basic_eval() {
-    fresh_env!("1 + 2", "3");
-    fresh_env!("let mut a = 1; a = 2", "Unit");
-    fresh_env!("let mut a = 1; a = 2; a", "2");
-    fresh_env!(r#"("a", 1 + 2)"#, r#"("a", 3)"#);
-  }
-
-  #[test]
-  fn function_eval() {
-    fresh_env!("fn oi(x) { x + 1 }; oi(4)", "5");
-    fresh_env!("fn oi(x) { x + 1 }; oi(1+2)", "4");
-  }
-
-  #[test]
-  fn scopes() {
-    let scope_ok = r#"
-    let a = 20
-    fn haha() {
-      let a = 10
-      a
-    }
-    haha()
-    "#;
-    fresh_env!(scope_ok, "10");
-    let scope_ok = r#"
-    let a = 20
-    fn haha() {
-      let a = 10
-      a
-    }
-    a
-    "#;
-    fresh_env!(scope_ok, "20");
-  }
-}

schala-lang/src/lib.rs

@@ -1,4 +1,3 @@
-#![feature(trace_macros)]
 #![feature(slice_patterns, box_patterns, box_syntax)]
 #![feature(proc_macro)]
 extern crate itertools;
@@ -6,14 +5,11 @@ extern crate itertools;
 extern crate lazy_static;
 #[macro_use]
 extern crate maplit;
-#[macro_use]
+
 extern crate schala_repl;
-#[macro_use]
 extern crate schala_codegen;
 
-use std::cell::RefCell;
-use std::rc::Rc;
-
+use std::collections::HashMap;
 use itertools::Itertools;
 use schala_repl::{ProgrammingLanguageInterface, EvalOptions, TraceArtifact, UnfinishedComputation, FinishedComputation};
 
@@ -21,127 +17,111 @@ macro_rules! bx {
   ($e:expr) => { Box::new($e) }
 }
 
-mod util;
 mod builtin;
+
 mod tokenizing;
-mod ast;
 mod parsing;
-mod symbol_table;
 mod typechecking;
-mod reduced_ast;
 mod eval;
 
-//trace_macros!(true);
-#[derive(ProgrammingLanguageInterface)]
-#[LanguageName = "Schala"]
-#[SourceFileExtension = "schala"]
-#[PipelineSteps(tokenizing, parsing(compact,expanded,trace), symbol_table, typechecking, ast_reducing, eval)]
+use self::typechecking::{TypeContext};
+
+/* TODO eventually custom-derive ProgrammingLanguageInterface with compiler passes as options */
 pub struct Schala {
   state: eval::State<'static>,
-  symbol_table: Rc<RefCell<symbol_table::SymbolTable>>,
-  type_context: typechecking::TypeContext<'static>,
+  type_context: TypeContext
 }
 
-
 impl Schala {
-  fn new_blank_env() -> Schala {
-    let symbols = Rc::new(RefCell::new(symbol_table::SymbolTable::new()));
-    Schala {
-      symbol_table: symbols.clone(),
-      type_context: typechecking::TypeContext::new(symbols.clone()),
-      state: eval::State::new(symbols),
-    }
-  }
-
   pub fn new() -> Schala {
-    let prelude = r#"
-type Option<T> = Some(T) | None
-    "#;
-    let mut s = Schala::new_blank_env();
-    s.execute_pipeline(prelude, &EvalOptions::default());
-    s
-  }
-}
-
-fn tokenizing(_handle: &mut Schala, input: &str, comp: Option<&mut UnfinishedComputation>) -> Result<Vec<tokenizing::Token>, String> {
-  let tokens = tokenizing::tokenize(input);
-  comp.map(|comp| {
-    let token_string = tokens.iter().map(|t| format!("{:?}<L:{},C:{}>", t.token_type, t.offset.0, t.offset.1)).join(", ");
-    comp.add_artifact(TraceArtifact::new("tokens", token_string));
-  });
-
-  let errors: Vec<String> = tokens.iter().filter_map(|t| t.get_error()).collect();
-  if errors.len() == 0 {
-    Ok(tokens)
-  } else {
-    Err(format!("{:?}", errors))
-  }
-}
-
-fn parsing(_handle: &mut Schala, input: Vec<tokenizing::Token>, comp: Option<&mut UnfinishedComputation>) -> Result<ast::AST, String> {
-
-  let (ast, trace) = parsing::parse(input);
-  comp.map(|comp| {
-    //TODO need to control which of these debug stages get added
-    let opt = comp.cur_debug_options.get(0).map(|s| s.clone());
-    match opt {
-      None => comp.add_artifact(TraceArtifact::new("ast", format!("{:?}", ast))),
-      Some(ref s) if s == "compact" => comp.add_artifact(TraceArtifact::new("ast", format!("{:?}", ast))),
-      Some(ref s) if s == "expanded" => comp.add_artifact(TraceArtifact::new("ast", format!("{:#?}", ast))),
-      Some(ref s) if s == "trace" => comp.add_artifact(TraceArtifact::new_parse_trace(trace)),
-      Some(ref x) => println!("Bad parsing debug option: {}", x),
-    };
-  });
-  ast.map_err(|err| err.msg)
-}
-
-fn symbol_table(handle: &mut Schala, input: ast::AST, comp: Option<&mut UnfinishedComputation>) -> Result<ast::AST, String> {
-  let add = handle.symbol_table.borrow_mut().add_top_level_symbols(&input);
-  match add {
-    Ok(()) => {
-      let artifact = TraceArtifact::new("symbol_table", handle.symbol_table.borrow().debug_symbol_table());
-      comp.map(|comp| comp.add_artifact(artifact));
-      Ok(input)
-    },
-    Err(msg) => Err(msg)
-  }
-}
-
-fn typechecking(handle: &mut Schala, input: ast::AST, comp: Option<&mut UnfinishedComputation>) -> Result<ast::AST, String> {
-  match handle.type_context.type_check_ast(&input) {
-    Ok(ty) => {
-      comp.map(|c| {
-        c.add_artifact(TraceArtifact::new("type_table", format!("{}", handle.type_context.debug_types())));
-        c.add_artifact(TraceArtifact::new("type_check", format!("{:?}", ty)));
-      });
-      Ok(input)
-    },
-    Err(msg) => {
-      comp.map(|comp| {
-        comp.add_artifact(TraceArtifact::new("type_table", format!("{}", handle.type_context.debug_types())));
-        comp.add_artifact(TraceArtifact::new("type_check", format!("Type error: {:?}", msg)));
-      });
-      Ok(input)
+    Schala {
+      state: eval::State::new(),
+      type_context: TypeContext::new(),
     }
   }
 }
 
-fn ast_reducing(handle: &mut Schala, input: ast::AST, comp: Option<&mut UnfinishedComputation>) -> Result<reduced_ast::ReducedAST, String> {
-  let ref symbol_table = handle.symbol_table.borrow();
-  let output = input.reduce(symbol_table);
-  comp.map(|comp| comp.add_artifact(TraceArtifact::new("ast_reducing", format!("{:?}", output))));
-  Ok(output)
+impl ProgrammingLanguageInterface for Schala {
+
+  schala_codegen::compiler_pass_sequence!(["tokenize", "parse", "yolo"]);
+
+  fn get_language_name(&self) -> String {
+    "Schala".to_string()
+  }
+
+  fn get_source_file_suffix(&self) -> String {
+    format!("schala")
+  }
+
+  fn execute(&mut self, input: &str, options: &EvalOptions) -> FinishedComputation {
+
+    let mut evaluation = UnfinishedComputation::default();
+
+    //tokenzing
+    let tokens = tokenizing::tokenize(input);
+    if options.debug.tokens {
+      let token_string = tokens.iter().map(|t| format!("{:?}<L:{},C:{}>", t.token_type, t.offset.0, t.offset.1)).join(", ");
+      evaluation.add_artifact(TraceArtifact::new("tokens", token_string));
+    }
+
+    {
+      let token_errors: Vec<&String> = tokens.iter().filter_map(|t| t.get_error()).collect();
+      if token_errors.len() != 0 {
+        return evaluation.output(Err(format!("Tokenization error: {:?}\n", token_errors)));
+      }
+    }
+
+    // parsing
+    let ast = match parsing::parse(tokens) {
+      (Ok(ast), trace) => {
+        if options.debug.parse_tree {
+          evaluation.add_artifact(TraceArtifact::new_parse_trace(trace));
+        }
+        if options.debug.ast {
+          evaluation.add_artifact(TraceArtifact::new("ast", format!("{:#?}", ast)));
+        }
+        ast
+      },
+      (Err(err), trace) => {
+        if options.debug.parse_tree {
+          evaluation.add_artifact(TraceArtifact::new_parse_trace(trace));
+        }
+        return evaluation.output(Err(format!("Parse error: {:?}\n", err.msg)));
+      }
+    };
+
+    //symbol table
+    match self.type_context.add_top_level_types(&ast) {
+      Ok(()) => (),
+      Err(msg) => {
+        if options.debug.type_checking {
+          evaluation.add_artifact(TraceArtifact::new("type_check", msg));
+        }
+      }
+    };
+
+    //typechecking
+    match self.type_context.type_check_ast(&ast) {
+      Ok(ty) => {
+        if options.debug.type_checking {
+          evaluation.add_artifact(TraceArtifact::new("type_check", format!("{:?}", ty)));
+        }
+      },
+      Err(msg) => evaluation.add_artifact(TraceArtifact::new("type_check", msg)),
+    };
+
+    let text = self.type_context.debug_symbol_table();
+    if options.debug.symbol_table {
+      evaluation.add_artifact(TraceArtifact::new("symbol_table", text));
+    }
+
+    let evaluation_outputs = self.state.evaluate(ast);
+    let text_output: Result<Vec<String>, String> = evaluation_outputs
+      .into_iter()
+      .collect();
+
+    let eval_output = text_output
+      .map(|v| { v.into_iter().intersperse(format!("\n")).collect() });
+    evaluation.output(eval_output)
+  }
 }
-
-fn eval(handle: &mut Schala, input: reduced_ast::ReducedAST, comp: Option<&mut UnfinishedComputation>) -> Result<String, String> {
-  comp.map(|comp| comp.add_artifact(TraceArtifact::new("value_state", handle.state.debug_print())));
-  let evaluation_outputs = handle.state.evaluate(input, true);
-  let text_output: Result<Vec<String>, String> = evaluation_outputs
-    .into_iter()
-    .collect();
-
-  let eval_output: Result<String, String> = text_output
-    .map(|v| { v.into_iter().intersperse(format!("\n")).collect() });
-  eval_output
-}
-

schala-lang/src/reduced_ast.rs

@@ -1,217 +0,0 @@
-use std::rc::Rc;
-
-use ast::{AST, Statement, Expression, Declaration, Discriminator, IfExpressionBody, Pattern};
-use symbol_table::{Symbol, SymbolSpec, SymbolTable};
-use builtin::{BinOp, PrefixOp};
-
-#[derive(Debug)]
-pub struct ReducedAST(pub Vec<Stmt>);
-
-#[derive(Debug, Clone)]
-pub enum Stmt {
-  PreBinding {
-    name: Rc<String>,
-    func: Func,
-  },
-  Binding {
-    name: Rc<String>,
-    constant: bool,
-    expr: Expr,
-  },
-  Expr(Expr),
-  Noop,
-}
-
-#[derive(Debug, Clone)]
-pub enum Expr {
-  Lit(Lit),
-  Func(Func),
-  Tuple(Vec<Expr>),
-  Constructor {
-    variant: usize,
-    expr: Box<Expr>,
-  },
-  Val(Rc<String>),
-  Call {
-    f: Box<Expr>,
-    args: Vec<Expr>,
-  },
-  Assign {
-    val: Box<Expr>,
-    expr: Box<Expr>,
-  },
-  Conditional {
-    cond: Box<Expr>,
-    then_clause: Vec<Stmt>,
-    else_clause: Vec<Stmt>,
-  },
-  Match {
-    cond: Box<Expr>,
-    arms: Vec<(Pattern, Vec<Stmt>)>
-  },
-  UnimplementedSigilValue
-}
-
-pub enum Pat {
-  Ignored
-}
-
-#[derive(Debug, Clone)]
-pub enum Lit {
-  Nat(u64),
-  Int(i64),
-  Float(f64),
-  Bool(bool),
-  StringLit(Rc<String>),
-  Custom(Rc<String>, Vec<Expr>),
-}
-
-#[derive(Debug, Clone)]
-pub enum Func {
-  BuiltIn(Rc<String>),
-  UserDefined {
-    name: Option<Rc<String>>,
-    params: Vec<Rc<String>>,
-    body: Vec<Stmt>,
-  }
-}
-
-impl AST {
-  pub fn reduce(&self, symbol_table: &SymbolTable) -> ReducedAST {
-    let mut output = vec![];
-    for statement in self.0.iter() {
-      output.push(statement.reduce(symbol_table));
-    }
-    ReducedAST(output)
-  }
-}
-
-impl Statement {
-  fn reduce(&self, symbol_table: &SymbolTable) -> Stmt {
-    use ast::Statement::*;
-    match self {
-      ExpressionStatement(expr) => Stmt::Expr(expr.reduce(symbol_table)),
-      Declaration(decl) => decl.reduce(symbol_table),
-    }
-  }
-}
-
-impl Expression {
-  fn reduce(&self, symbol_table: &SymbolTable) -> Expr {
-    use ast::ExpressionType::*;
-    let ref input = self.0;
-    match input {
-      NatLiteral(n) => Expr::Lit(Lit::Nat(*n)),
-      FloatLiteral(f) => Expr::Lit(Lit::Float(*f)),
-      StringLiteral(s) => Expr::Lit(Lit::StringLit(s.clone())),
-      BoolLiteral(b) => Expr::Lit(Lit::Bool(*b)),
-      BinExp(binop, lhs, rhs) => binop.reduce(symbol_table, lhs, rhs),
-      PrefixExp(op, arg) => op.reduce(symbol_table, arg),
-      //remember Some(5) is  a CallExpr
-      // => ast: Ok(AST([ExpressionStatement(Expression(Call { f: Expression(Value("Some"), None), arguments: [Expression(NatLiteral(5), None)] }, None))]))
-      Value(name) => {
-        match symbol_table.values.get(name) {
-          Some(Symbol { spec: SymbolSpec::DataConstructor { type_args, .. }, .. }) => {
-            Expr::Constructor { type_name: name.clone() }
-          },
-          _ => Expr::Val(name.clone()),
-        }
-      },
-      Call { f, arguments } => Expr::Call {
-        f: Box::new(f.reduce(symbol_table)),
-        args: arguments.iter().map(|arg| arg.reduce(symbol_table)).collect(),
-      },
-      TupleLiteral(exprs) => Expr::Tuple(exprs.iter().map(|e| e.reduce(symbol_table)).collect()),
-      IfExpression { discriminator, body } => reduce_if_expression(discriminator, body, symbol_table),
-      _ => Expr::UnimplementedSigilValue,
-    }
-  }
-}
-
-fn reduce_if_expression(discriminator: &Discriminator, body: &IfExpressionBody, symbol_table: &SymbolTable) -> Expr {
-  let cond = Box::new(match *discriminator {
-    Discriminator::Simple(ref expr) => expr.reduce(symbol_table),
-    _ => panic!(),
-  });
-  match *body {
-    IfExpressionBody::SimpleConditional(ref then_clause, ref else_clause) => {
-      let then_clause = then_clause.iter().map(|expr| expr.reduce(symbol_table)).collect();
-      let else_clause = match else_clause {
-        None => vec![],
-        Some(stmts) => stmts.iter().map(|expr| expr.reduce(symbol_table)).collect(),
-      };
-      Expr::Conditional { cond, then_clause, else_clause }
-    },
-    IfExpressionBody::SimplePatternMatch(ref pat, ref then_clause, ref else_clause) => {
-      let then_clause = then_clause.iter().map(|expr| expr.reduce(symbol_table)).collect();
-      let else_clause = match else_clause {
-        None => vec![],
-        Some(stmts) => stmts.iter().map(|expr| expr.reduce(symbol_table)).collect(),
-      };
-      Expr::Match {
-        cond,
-        arms: vec![
-          (pat.clone(), then_clause),
-          (Pattern::Ignored, else_clause)
-        ],
-      }
-    },
-    IfExpressionBody::GuardList(ref _guard_arms) => panic!(),
-  }
-}
-
-impl Pattern {
-  fn reduce(&self, symbol_table: &SymbolTable) -> Pat {
-    match self {
-      Pattern::Ignored => Pat::Ignored,
-      Pattern::TuplePattern(_) => panic!(),
-      Pattern::Literal(_) => panic!(),
-      Pattern::TupleStruct(_, _) => panic!(),
-      Pattern::Record(_, _) => panic!(),
-    }
-  }
-}
-
-impl Declaration {
-  fn reduce(&self, symbol_table: &SymbolTable) -> Stmt {
-    use self::Declaration::*;
-    use ::ast::Signature;
-    match self {
-      Binding {name, constant, expr } => Stmt::Binding { name: name.clone(), constant: *constant, expr: expr.reduce(symbol_table) },
-      FuncDecl(Signature { name, params, .. }, statements) => Stmt::PreBinding {
-        name: name.clone(),
-        func: Func::UserDefined {
-          name: Some(name.clone()),
-          params: params.iter().map(|param| param.0.clone()).collect(),
-          body: statements.iter().map(|stmt| stmt.reduce(symbol_table)).collect(),
-        }
-      },
-      TypeDecl { .. } => Stmt::Noop,
-      TypeAlias(_, _) => Stmt::Noop,
-      Interface { .. } => Stmt::Noop,
-      Impl { .. } => Stmt::Expr(Expr::UnimplementedSigilValue),
-      _ => Stmt::Expr(Expr::UnimplementedSigilValue)
-    }
-  }
-}
-
-impl BinOp {
-  fn reduce(&self, symbol_table: &SymbolTable, lhs: &Box<Expression>, rhs: &Box<Expression>) -> Expr {
-    if **self.sigil() == "=" {
-      Expr::Assign {
-        val: Box::new(lhs.reduce(symbol_table)),
-        expr: Box::new(rhs.reduce(symbol_table)),
-      }
-    } else {
-      let f = Box::new(Expr::Func(Func::BuiltIn(self.sigil().clone())));
-      Expr::Call { f, args: vec![lhs.reduce(symbol_table), rhs.reduce(symbol_table)]}
-    }
-  }
-}
-
-impl PrefixOp {
-  fn reduce(&self, symbol_table: &SymbolTable, arg: &Box<Expression>) -> Expr {
-    let f = Box::new(Expr::Func(Func::BuiltIn(self.sigil().clone())));
-    Expr::Call { f, args: vec![arg.reduce(symbol_table)]}
-  }
-}

schala-lang/src/symbol_table.rs

@@ -1,121 +0,0 @@
-use std::collections::HashMap;
-use std::rc::Rc;
-use std::fmt;
-use std::fmt::Write;
-
-use ast;
-use typechecking::TypeName;
-
-//cf. p. 150 or so of Language Implementation Patterns
-pub struct SymbolTable {
-  pub values: HashMap<Rc<String>, Symbol> //TODO this will eventually have real type information
-}
-
-impl SymbolTable {
-  pub fn new() -> SymbolTable {
-    SymbolTable { values: HashMap::new() }
-  }
-}
-
-#[derive(Debug)]
-pub struct Symbol {
-  pub name: Rc<String>,
-  pub spec: SymbolSpec,
-}
-
-impl fmt::Display for Symbol {
-  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-    write!(f, "<Name: {}, Spec: {}>", self.name, self.spec)
-  }
-}
-
-#[derive(Debug)]
-pub enum SymbolSpec {
-  Func(Vec<TypeName>),
-  DataConstructor {
-    type_name: Rc<String>,
-    type_args: Vec<Rc<String>>,
-  },
-}
-
-impl fmt::Display for SymbolSpec {
-  fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-    use self::SymbolSpec::*;
-    match self {
-      Func(type_names) => write!(f, "Func({:?})", type_names),
-      DataConstructor { type_name, type_args } => write!(f, "DataConstructor({:?} -> {})", type_args, type_name),
-    }
-  }
-}
-
-impl SymbolTable {
-  /* note: this adds names for *forward reference* but doesn't actually create any types. solve that problem
-   * later */
-  pub fn add_top_level_symbols(&mut self, ast: &ast::AST) -> Result<(), String> {
-    use self::ast::{Statement, TypeName, Variant, TypeSingletonName, TypeBody};
-    use self::ast::Declaration::*;
-    for statement in ast.0.iter() {
-      if let Statement::Declaration(decl) = statement {
-        match decl {
-          FuncSig(signature) | FuncDecl(signature, _) => {
-            let mut ch: char = 'a';
-            let mut types = vec![];
-            for param in signature.params.iter() {
-              match param {
-                (_, Some(ty)) => {
-                  //TODO eventually handle this case different
-                  types.push(Rc::new(format!("{}", ch)));
-                  ch = ((ch as u8) + 1) as char;
-                },
-                (_, None) => {
-                  types.push(Rc::new(format!("{}", ch)));
-                  ch = ((ch as u8) + 1) as char;
-                }
-              }
-            }
-            let spec = SymbolSpec::Func(types);
-            self.values.insert(
-              signature.name.clone(),
-              Symbol { name: signature.name.clone(), spec }
-              );
-          },
-          TypeDecl { name: TypeSingletonName { name, params}, body: TypeBody(variants), mutable } => {
-            for var in variants {
-              match var {
-                Variant::UnitStruct(variant_name) => {
-                  let spec = SymbolSpec::DataConstructor {
-                    type_name: name.clone(),
-                    type_args: vec![],
-                  };
-                  self.values.insert(variant_name.clone(), Symbol { name: variant_name.clone(), spec });
-                },
-                Variant::TupleStruct(variant_name, tuple_members) => {
-                  let type_args = tuple_members.iter().map(|type_name| match type_name {
-                    TypeName::Singleton(TypeSingletonName { name, ..}) => name.clone(),
-                    TypeName::Tuple(_) => unimplemented!(),
-                  }).collect();
-                  let spec = SymbolSpec::DataConstructor { 
-                    type_name: name.clone(),
-                    type_args
-                  };
-                  let symbol = Symbol { name: variant_name.clone(), spec };
-                  self.values.insert(variant_name.clone(), symbol);
-                },
-                e => return Err(format!("{:?} not supported in typing yet", e)),
-              }
-            }
-          },
-          _ => ()
-        }
-      }
-    }
-    Ok(())
-  }
-  pub fn debug_symbol_table(&self) -> String {
-    let mut output = format!("Symbol table\n");
-    for (name, sym) in &self.values {
-      write!(output, "{} -> {}\n", name, sym).unwrap();
-    }
-    output
-  }
-}

schala-lang/src/tokenizing.rs

@@ -3,6 +3,7 @@ use std::collections::HashMap;
 use std::rc::Rc;
 use std::iter::{Iterator, Peekable};
 use std::fmt;
+use ::schala_codegen;
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum TokenType {
@@ -45,13 +46,11 @@ impl fmt::Display for TokenType {
 
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub enum Kw {
-  If, Then, Else,
-  Is,
+  If, Else,
   Func,
-  For, While,
+  For,
   Match,
-  Const, Let, In,
-  Mut,
+  Var, Const, Let, In,
   Return,
   Alias, Type, SelfType, SelfIdent,
   Interface, Impl,
@@ -63,16 +62,14 @@ lazy_static! {
   static ref KEYWORDS: HashMap<&'static str, Kw> =
     hashmap! {
       "if" => Kw::If,
-      "then" => Kw::Then,
       "else" => Kw::Else,
-      "is" => Kw::Is,
       "fn" => Kw::Func,
       "for" => Kw::For,
-      "while" => Kw::While,
+      "match" => Kw::Match,
+      "var" => Kw::Var,
       "const" => Kw::Const,
       "let" => Kw::Let,
       "in" => Kw::In,
-      "mut" => Kw::Mut,
       "return" => Kw::Return,
       "alias" => Kw::Alias,
       "type" => Kw::Type,
@@ -93,9 +90,9 @@ pub struct Token {
 }
 
 impl Token {
-  pub fn get_error(&self) -> Option<String> {
+  pub fn get_error(&self) -> Option<&String> {
     match self.token_type {
-      TokenType::Error(ref s) => Some(s.clone()),
+      TokenType::Error(ref s) => Some(s),
       _ => None,
     }
   }
@@ -109,8 +106,9 @@ fn is_operator(c: &char) -> bool {
   OPERATOR_CHARS.iter().any(|x| x == c)
 }
 
-type CharData = (usize, usize, char);
+type CharIter<I: Iterator<Item=(usize,usize,char)>> = Peekable<I>;
 
+#[schala_codegen::compiler_pass = "tokenization"]
 pub fn tokenize(input: &str) -> Vec<Token> {
   let mut tokens: Vec<Token> = Vec::new();
 
@@ -168,7 +166,7 @@ pub fn tokenize(input: &str) -> Vec<Token> {
   tokens
 }
 
-fn handle_digit(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenType {
+fn handle_digit<I: Iterator<Item=(usize,usize,char)>>(c: char, input: &mut CharIter<I>) -> TokenType {
   if c == '0' && input.peek().map_or(false, |&(_, _, c)| { c == 'x' }) {
     input.next();
     let rest: String = input.peeking_take_while(|&(_, _, ref c)| c.is_digit(16) || *c == '_').map(|(_, _, c)| { c }).collect();
@@ -183,7 +181,7 @@ fn handle_digit(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) ->
   }
 }
 
-fn handle_quote(input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenType {
+fn handle_quote<I: Iterator<Item=(usize,usize,char)>>(input: &mut CharIter<I>) -> TokenType {
   let mut buf = String::new();
   loop {
     match input.next().map(|(_, _, c)| { c }) {
@@ -208,7 +206,7 @@ fn handle_quote(input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenType
   TokenType::StrLiteral(Rc::new(buf))
 }
 
-fn handle_alphabetic(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenType {
+fn handle_alphabetic<I: Iterator<Item=(usize,usize,char)>>(c: char, input: &mut CharIter<I>) -> TokenType {
   let mut buf = String::new();
   buf.push(c);
   if c == '_' && input.peek().map(|&(_, _, c)| { !c.is_alphabetic() }).unwrap_or(true) {
@@ -231,7 +229,7 @@ fn handle_alphabetic(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>
   }
 }
 
-fn handle_operator(c: char, input: &mut Peekable<impl Iterator<Item=CharData>>) -> TokenType {
+fn handle_operator<I: Iterator<Item=(usize,usize,char)>>(c: char, input: &mut CharIter<I>) -> TokenType {
   match c {
     '<' | '>' | '|' | '.' => {
       let ref next = input.peek().map(|&(_, _, c)| { c });

schala-lang/src/typechecking.rs

@@ -1,381 +1,163 @@
-use std::cell::RefCell;
 use std::rc::Rc;
 use std::collections::HashMap;
+use std::char;
 use std::fmt;
 use std::fmt::Write;
-/*
-use std::collections::hash_set::Union;
-use std::iter::Iterator;
+
 use itertools::Itertools;
-*/
 
-use ast;
-use util::StateStack;
-use symbol_table::{SymbolSpec, SymbolTable};
+use parsing;
 
-pub type TypeName = Rc<String>;
-type TypeResult<T> = Result<T, String>;
+pub struct TypeContext { 
+  type_var_count: u64,
+  bindings: HashMap<Rc<String>, Type>,
+}
 
 #[derive(Debug, PartialEq, Clone)]
-enum Type {
+pub enum Type {
   Const(TConst),
-  Var(TypeName),
-  Func(Vec<Type>),
+  Sum(Vec<Type>),
+  Func(Box<Type>, Box<Type>),
+  UVar(String),
+  EVar(u64),
+  Void
 }
 
-#[derive(Debug, PartialEq, Clone)]
-enum TConst {
-  Unit,
-  Nat,
-  StringT,
-  Custom(String)
-}
-
-#[derive(Debug, PartialEq, Clone)]
-struct Scheme {
-  names: Vec<TypeName>,
-  ty: Type,
-}
-
-impl fmt::Display for Scheme {
+impl fmt::Display for Type {
   fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-    write!(f, "∀{:?} . {:?}", self.names, self.ty)
-  }
-}
-
-#[derive(Debug, PartialEq, Clone)]
-struct Substitution(HashMap<TypeName, Type>);
-impl Substitution {
-  fn empty() -> Substitution {
-    Substitution(HashMap::new())
-  }
-}
-
-#[derive(Debug, PartialEq, Clone)]
-struct TypeEnv(HashMap<TypeName, Scheme>);
-
-impl TypeEnv {
-  fn default() -> TypeEnv {
-    TypeEnv(HashMap::new())
-  }
-
-  fn populate_from_symbols(&mut self, symbol_table: &SymbolTable) {
-    for (name, symbol) in symbol_table.values.iter() {
-      if let SymbolSpec::Func(ref type_names) = symbol.spec {
-        let mut ch: char = 'a';
-        let mut names = vec![];
-        for _ in type_names.iter() {
-          names.push(Rc::new(format!("{}", ch)));
-          ch = ((ch as u8) + 1) as char;
+    use self::Type::*;
+    match self {
+      &Const(ref c) => write!(f, "{:?}", c),
+      &Sum(ref types) => {
+        write!(f, "(")?;
+        for item in types.iter().map(|ty| Some(ty)).intersperse(None) {
+          match item {
+            Some(ty) => write!(f, "{}", ty)?,
+            None => write!(f, ",")?,
+          };
         }
-
-        let sigma = Scheme {
-          names: names.clone(),
-          ty: Type::Func(names.into_iter().map(|n| Type::Var(n)).collect())
-        };
-        self.0.insert(name.clone(), sigma);
-      }
+        write!(f, ")")
+      },
+      &Func(ref a, ref b) => write!(f, "{} -> {}", a, b),
+      &UVar(ref s) => write!(f, "{}_u", s),
+      &EVar(ref n) => write!(f, "{}_e", n),
+      &Void => write!(f, "Void")
     }
   }
 }
 
-pub struct TypeContext<'a> {
-  values: StateStack<'a, TypeName, Type>,
-  symbol_table_handle: Rc<RefCell<SymbolTable>>,
-  global_env: TypeEnv
+#[derive(Default)]
+struct UVarGenerator {
+  n: u32,
 }
-
-impl<'a> TypeContext<'a> {
-  pub fn new(symbol_table_handle: Rc<RefCell<SymbolTable>>) -> TypeContext<'static> {
-    TypeContext { values: StateStack::new(None), global_env: TypeEnv::default(), symbol_table_handle }
+impl UVarGenerator {
+  fn new() -> UVarGenerator {
+    UVarGenerator::default()
   }
-
-  pub fn debug_types(&self) -> String {
-    let mut output = format!("Type environment\n");
-    for (name, scheme) in &self.global_env.0 {
-      write!(output, "{} -> {}\n", name, scheme).unwrap();
-    }
-    output
-  }
-
-  pub fn type_check_ast(&mut self, input: &ast::AST) -> Result<String, String> {
-    let ref symbol_table = self.symbol_table_handle.borrow();
-    self.global_env.populate_from_symbols(symbol_table);
-    let output = self.global_env.infer_block(&input.0)?;
-    Ok(format!("{:?}", output))
+  fn next(&mut self) -> Type {
+    //TODO handle this in the case where someone wants to make a function with more than 26 variables
+    let s = format!("{}", unsafe { char::from_u32_unchecked(self.n + ('a' as u32)) });
+    self.n += 1;
+    Type::UVar(s)
   }
 }
 
-impl TypeEnv {
-  fn instantiate(&mut self, sigma: Scheme) -> Type {
-    match sigma {
-      Scheme { ty, .. } => ty,
-    }
-  }
-  fn generate(&mut self, ty: Type) -> Scheme {
-    Scheme {
-      names: vec![], //TODO incomplete
-      ty
-    }
-  }
-  fn infer_block(&mut self, block: &Vec<ast::Statement>) -> TypeResult<Type> {
-    let mut output = Type::Const(TConst::Unit);
-    for statement in block {
-      output = self.infer_statement(statement)?;
-    }
-    Ok(output)
-  }
-  fn infer_statement(&mut self, statement: &ast::Statement) -> TypeResult<Type> {
-    match statement {
-      ast::Statement::ExpressionStatement(expr) => self.infer_expr(expr),
-      ast::Statement::Declaration(decl) => self.infer_decl(decl)
-    }
-  }
-  fn infer_decl(&mut self, decl: &ast::Declaration) -> TypeResult<Type> {
-    use ast::Declaration::*;
-    match decl {
-      Binding { name, expr, .. } => {
-        let ty = self.infer_expr(expr)?;
-        let sigma = self.generate(ty);
-        self.0.insert(name.clone(), sigma);
-      },
-      _ => (),
-    }
-    Ok(Type::Const(TConst::Unit))
-  }
-  fn infer_expr(&mut self, expr: &ast::Expression) -> TypeResult<Type> {
-    match expr {
-      ast::Expression(expr, Some(anno)) => {
-        self.infer_exprtype(expr)
-      },
-      ast::Expression(expr, None) => {
-        self.infer_exprtype(expr)
-      }
-    }
-  }
-
-  fn infer_exprtype(&mut self, expr: &ast::ExpressionType) -> TypeResult<Type> {
-    use self::TConst::*;
-    use ast::ExpressionType::*;
-    Ok(match expr {
-      NatLiteral(_) => Type::Const(Nat),
-      StringLiteral(_) => Type::Const(StringT),
-      BinExp(op, lhs, rhs) => {
-
-        return Err(format!("NOTDONE"))
-      },
-      Call { f, arguments } =>  {
-
-        return Err(format!("NOTDONE"))
-      },
-      Value(name) => {
-        let s = match self.0.get(name) {
-          Some(sigma) => sigma.clone(),
-          None => return Err(format!("Unknown variable: {}", name))
-        };
-        self.instantiate(s)
-      },
-      _ => Type::Const(Unit)
-    })
-  }
+#[derive(Debug, PartialEq, Clone)]
+pub enum TConst {
+  Unit,
+  Int,
+  Float,
+  StringT,
+  Bool,
+  Custom(String),
 }
 
-
-/* GIANT TODO - use the rust im crate, unless I make this code way less haskell-ish after it's done
-  */
-
-/*
-
-
-pub type TypeResult<T> = Result<T, String>;
-*/
-
-/* TODO this should just check the name against a map, and that map should be pre-populated with
- * types */
-/*
 impl parsing::TypeName {
   fn to_type(&self) -> TypeResult<Type> {
-	use self::parsing::TypeSingletonName;
-	use self::parsing::TypeName::*;
-	use self::Type::*; use self::TConstOld::*;
+    use self::parsing::TypeSingletonName;
+    use self::parsing::TypeName::*;
+    use self::Type::*; use self::TConst::*;
     Ok(match self {
-      Tuple(_) => return Err(format!("Tuples not yet implemented")),
-      Singleton(name) => match name {
-        TypeSingletonName { name, .. } => match &name[..] {
-          /*
-          "Nat" => Const(Nat),
+      &Tuple(_) => return Err(format!("Tuples not yet implemented")),
+      &Singleton(ref name) => match name {
+        &TypeSingletonName { ref name, .. } => match &name[..] {
           "Int" => Const(Int),
           "Float" => Const(Float),
           "Bool" => Const(Bool),
           "String" => Const(StringT),
-          */
           n => Const(Custom(n.to_string()))
         }
       }
     })
   }
 }
-*/
 
+pub type TypeResult<T> = Result<T, String>;
 
-
-/*
 impl TypeContext {
-  pub fn type_check_ast(&mut self, ast: &parsing::AST) -> TypeResult<String> {
-    let ref block = ast.0;
-    let mut infer = Infer::default();
-    let env = TypeEnvironment::default();
-    let output = infer.infer_block(block, &env);
-    match output {
-      Ok(s) => Ok(format!("{:?}", s)),
-      Err(s) => Err(format!("Error: {:?}", s))
-    }
+  pub fn new() -> TypeContext {
+    TypeContext { bindings: HashMap::new(), type_var_count: 0 }
+  }
+  pub fn fresh(&mut self) -> Type {
+    let ret = self.type_var_count;
+    self.type_var_count += 1;
+    Type::EVar(ret)
   }
 }
 
-// this is the equivalent of the Haskell Infer monad
-#[derive(Debug, Default)]
-struct Infer {
-  _idents: u32,
-}
-
-#[derive(Debug)]
-enum InferError {
-  CannotUnify(MonoType, MonoType),
-  OccursCheckFailed(Rc<String>, MonoType),
-  UnknownIdentifier(Rc<String>),
-  Custom(String),
-}
-
-type InferResult<T> = Result<T, InferError>;
-
-
-impl Infer {
-  fn fresh(&mut self) -> MonoType {
-    let i = self._idents;
-    self._idents += 1;
-    let name = Rc::new(format!("{}", ('a' as u8 + 1) as char));
-    MonoType::Var(name)
-  }
-
-  fn unify(&mut self, a: MonoType, b: MonoType) -> InferResult<Substitution> {
-    use self::InferError::*; use self::MonoType::*;
-    Ok(match (a, b) {
-      (Const(ref a), Const(ref b)) if a == b => Substitution::new(),
-      (Var(ref name), ref var) => Substitution::bind_variable(name, var),
-      (ref var, Var(ref name)) => Substitution::bind_variable(name, var),
-      (Function(box a1, box b1), Function(box a2, box b2)) => {
-        let s1 = self.unify(a1, a2)?;
-        let s2 = self.unify(b1.apply_substitution(&s1), b2.apply_substitution(&s1))?;
-        s1.merge(s2)
-      },
-      (a, b) => return Err(CannotUnify(a, b))
-    })
-  }
-
-  fn infer_block(&mut self, block: &Vec<parsing::Statement>, env: &TypeEnvironment) -> InferResult<MonoType> {
-    use self::parsing::Statement;
-    let mut ret = MonoType::Const(TypeConst::Unit);
-    for statement in block.iter() {
-      ret = match statement {
-        Statement::ExpressionStatement(expr) => {
-          let (sub, ty) = self.infer_expr(expr, env)?;
-          //TODO handle substitution monadically
-
-          ty
+impl TypeContext {
+  pub fn add_top_level_types(&mut self, ast: &parsing::AST) -> TypeResult<()> {
+    use self::parsing::TypeName;
+    use self::parsing::Declaration::*;
+    use self::Type::*;
+    for statement in ast.0.iter() {
+      if let &self::parsing::Statement::Declaration(ref decl) = statement {
+        match decl {
+          &FuncSig(ref signature) | &FuncDecl(ref signature, _) => {
+            let mut uvar_gen = UVarGenerator::new();
+            let mut ty: Type = signature.type_anno.as_ref().map(|name: &TypeName| name.to_type()).unwrap_or_else(|| {Ok(uvar_gen.next())} )?;
+            for &(_, ref type_name) in signature.params.iter().rev() {
+              let arg_type = type_name.as_ref().map(|name| name.to_type()).unwrap_or_else(|| {Ok(uvar_gen.next())} )?;
+              ty = Func(bx!(arg_type), bx!(ty));
+            }
+            self.bindings.insert(signature.name.clone(), ty);
+          },
+          _ => ()
         }
-        Statement::Declaration(decl) => MonoType::Const(TypeConst::Unit),
       }
     }
-    Ok(ret)
+    Ok(())
   }
-
-  fn infer_expr(&mut self, expr: &parsing::Expression, env: &TypeEnvironment) -> InferResult<(Substitution, MonoType)> {
-    use self::parsing::Expression;
-    match expr {
-      Expression(e, Some(anno)) => self.infer_annotated_expr(e, anno, env),
-      /*
-        let anno_ty = anno.to_type()?;
-        let ty = self.infer_exprtype(&e)?;
-        self.unify(ty, anno_ty)
-      },
-      */
-      Expression(e, None) => self.infer_exprtype(e, env)
+  pub fn debug_symbol_table(&self) -> String {
+    let mut output = format!("Symbols\n");
+    for (sym, ty) in &self.bindings {
+      write!(output, "{} : {}\n", sym, ty).unwrap();
     }
-  }
-
-  fn infer_annotated_expr(&mut self, expr: &parsing::ExpressionType, anno: &parsing::TypeName, env: &TypeEnvironment) -> InferResult<(Substitution, MonoType)> {
-    Err(InferError::Custom(format!("exprtype not done: {:?}", expr)))
-  }
-  fn infer_exprtype(&mut self, expr: &parsing::ExpressionType, env: &TypeEnvironment) -> InferResult<(Substitution, MonoType)> {
-    use self::parsing::ExpressionType::*;
-    use self::TypeConst::*;
-    Ok(match expr {
-      NatLiteral(_) => (Substitution::new(), MonoType::Const(Nat)),
-      FloatLiteral(_) => (Substitution::new(), MonoType::Const(Float)),
-      StringLiteral(_) => (Substitution::new(), MonoType::Const(StringT)),
-      BoolLiteral(_) => (Substitution::new(), MonoType::Const(Bool)),
-      Value(name) => match env.lookup(name) {
-        Some(sigma) => {
-          let tau = self.instantiate(&sigma);
-          (Substitution::new(), tau)
-        },
-        None => return Err(InferError::UnknownIdentifier(name.clone())),
-      },
-      e => return Err(InferError::Custom(format!("Type inference for {:?} not done", e)))
-    })
-  }
-  fn instantiate(&mut self, sigma: &PolyType) -> MonoType {
-    let ref ty: MonoType = sigma.1;
-    let mut subst = Substitution::new();
-
-    for name in sigma.0.iter() {
-      let fresh_mvar = self.fresh();
-      let new = Substitution::bind_variable(name, &fresh_mvar);
-      subst = subst.merge(new);
-    }
-    ty.apply_substitution(&subst)
+    output
   }
 }
-*/
 
-
-
-
-
-
-
-
-
-
-
-
-/* OLD STUFF DOWN HERE */
-
-
-
-/*
 impl TypeContext {
-  fn infer_block(&mut self, statements: &Vec<parsing::Statement>) -> TypeResult<Type> {
-    let mut ret_type = Type::Const(TConst::Unit);
-    for statement in statements {
-      ret_type = self.infer_statement(statement)?;
+  pub fn type_check_ast(&mut self, ast: &parsing::AST) -> TypeResult<Type> {
+    use self::Type::*; use self::TConst::*;
+    let mut ret_type = Const(Unit);
+    for statement in ast.0.iter() {
+      ret_type = self.type_check_statement(statement)?;
     }
     Ok(ret_type)
   }
-
-  fn infer_statement(&mut self, statement: &parsing::Statement) -> TypeResult<Type> {
+  fn type_check_statement(&mut self, statement: &parsing::Statement) -> TypeResult<Type> {
     use self::parsing::Statement::*;
     match statement {
-      ExpressionStatement(expr) => self.infer(expr),
-      Declaration(decl) => self.add_declaration(decl),
+      &ExpressionStatement(ref expr) => self.infer(expr),
+      &Declaration(ref decl) => self.add_declaration(decl),
     }
   }
   fn add_declaration(&mut self, decl: &parsing::Declaration) -> TypeResult<Type> {
     use self::parsing::Declaration::*;
     use self::Type::*;
     match decl {
-      Binding { name, expr, .. } => {
+      &Binding { ref name, ref expr, .. } => {
         let ty = self.infer(expr)?;
         self.bindings.insert(name.clone(), ty);
       },
@@ -386,23 +168,23 @@ impl TypeContext {
   fn infer(&mut self, expr: &parsing::Expression) -> TypeResult<Type> {
     use self::parsing::Expression;
     match expr {
-      Expression(e, Some(anno)) => {
+      &Expression(ref e, Some(ref anno)) => {
         let anno_ty = anno.to_type()?;
         let ty = self.infer_exprtype(&e)?;
         self.unify(ty, anno_ty)
       },
-      Expression(e, None) => self.infer_exprtype(e)
+      &Expression(ref e, None) => self.infer_exprtype(e)
     }
   }
   fn infer_exprtype(&mut self, expr: &parsing::ExpressionType) -> TypeResult<Type> {
     use self::parsing::ExpressionType::*;
     use self::Type::*; use self::TConst::*;
     match expr {
-      NatLiteral(_) => Ok(Const(Nat)),
-      FloatLiteral(_) => Ok(Const(Float)),
-      StringLiteral(_) => Ok(Const(StringT)),
-      BoolLiteral(_) => Ok(Const(Bool)),
-      BinExp(op, lhs, rhs) => { /* remember there are both the haskell convention talk and the write you a haskell ways to do this! */
+      &IntLiteral(_) => Ok(Const(Int)),
+      &FloatLiteral(_) => Ok(Const(Float)),
+      &StringLiteral(_) => Ok(Const(StringT)),
+      &BoolLiteral(_) => Ok(Const(Bool)),
+      &BinExp(ref op, ref lhs, ref rhs) => { /* remember there are both the haskell convention talk and the write you a haskell ways to do this! */
         match op.get_type()? {
           Func(box t1, box Func(box t2, box t3)) => {
             let lhs_ty = self.infer(lhs)?;
@@ -414,7 +196,7 @@ impl TypeContext {
           other => Err(format!("{:?} is not a binary function type", other))
         }
       },
-      PrefixExp(op, expr) => match op.get_type()? {
+      &PrefixExp(ref op, ref expr) => match op.get_type()? {
         Func(box t1, box t2) => {
           let expr_ty = self.infer(expr)?;
           self.unify(t1, expr_ty)?;
@@ -422,13 +204,13 @@ impl TypeContext {
         },
         other => Err(format!("{:?} is not a prefix op function type", other))
       },
-      Value(name) => {
+      &Value(ref name) => {
         match self.bindings.get(name) {
           Some(ty) => Ok(ty.clone()),
           None => Err(format!("No binding found for variable: {}", name)),
         }
       },
-      Call { f, arguments } => {
+      &Call { ref f, ref arguments } => {
         let mut tf = self.infer(f)?;
         for arg in arguments.iter() {
           match tf {
@@ -442,13 +224,22 @@ impl TypeContext {
         }
         Ok(tf)
       },
-      TupleLiteral(expressions) => {
+      &TupleLiteral(ref expressions) => {
         let mut types = vec![];
         for expr in expressions {
           types.push(self.infer(expr)?);
         }
         Ok(Sum(types))
       },
+      /*
+  Index {
+    indexee: Box<Expression>,
+    indexers: Vec<Expression>,
+  },
+  IfExpression(Box<Expression>, Vec<Statement>, Option<Vec<Statement>>),
+  MatchExpression(Box<Expression>, Vec<MatchArm>),
+  ForExpression
+      */
       _ => Err(format!("Type not yet implemented"))
     }
   }
@@ -460,34 +251,4 @@ impl TypeContext {
     }
   }
 }
-*/
 
-
-#[cfg(test)]
-mod tests {
-  /*
-  use super::{Type, TConst, TypeContext};
-  use super::Type::*;
-  use super::TConst::*;
-  use std::rc::Rc;
-  use std::cell::RefCell;
-
-  macro_rules! type_test {
-    ($input:expr, $correct:expr) => {
-      {
-      let symbol_table = Rc::new(RefCell::new(SymbolTable::new()));
-      let mut tc = TypeContext::new(symbol_table);
-      let ast = ::ast::parse(::tokenizing::tokenize($input)).0.unwrap() ;
-      //tc.add_symbols(&ast);
-      assert_eq!($correct, tc.infer_block(&ast.0).unwrap())
-      }
-    }
-  }
-
-  #[test]
-  fn basic_inference() {
-    type_test!("30", Const(Nat));
-    //type_test!("fn x(a: Int): Bool {}; x(1)", TConst(Boolean));
-  }
-  */
-}

schala-lang/src/util.rs

@@ -1,43 +0,0 @@
-use std::collections::HashMap;
-use std::hash::Hash;
-use std::cmp::Eq;
-
-//TODO rename this ScopeStack
-#[derive(Default, Debug)]
-pub struct StateStack<'a, T: 'a, V: 'a>  where T: Hash + Eq {
-  parent: Option<&'a StateStack<'a, T, V>>,
-  values: HashMap<T, V>,
-  scope_name: Option<String>
-}
-
-impl<'a, T, V> StateStack<'a, T, V> where T: Hash + Eq {
-  pub fn new(name: Option<String>) -> StateStack<'a, T, V> where T: Hash + Eq {
-    StateStack {
-      parent: None,
-      values: HashMap::new(),
-      scope_name: name
-    }
-  }
-  pub fn insert(&mut self, key: T, value: V) where T: Hash + Eq {
-    self.values.insert(key, value);
-  }
-  pub fn lookup(&self, key: &T) -> Option<&V> where T: Hash + Eq {
-    match (self.values.get(key), self.parent) {
-      (None, None) => None,
-      (None, Some(parent)) => parent.lookup(key),
-      (Some(value), _) => Some(value),
-    }
-  }
-  //TODO rename new_scope
-  pub fn new_frame(&'a self, name: Option<String>) -> StateStack<'a, T, V> where T: Hash + Eq {
-    StateStack {
-      parent: Some(self),
-      values: HashMap::default(),
-      scope_name: name,
-    }
-  }
-  pub fn get_name(&self) -> Option<&String> {
-    self.scope_name.as_ref()
-  }
-}
-

schala-repl/Cargo.toml

@@ -14,13 +14,12 @@ colored = "1.5"
 serde = "1.0.15"
 serde_derive = "1.0.15"
 serde_json = "1.0.3"
-rocket = "0.3.13"
-rocket_codegen = "0.3.13"
-rocket_contrib = "0.3.13"
+rocket = "0.3.5"
+rocket_codegen = "0.3.5"
+rocket_contrib = "0.3.5"
 phf = "0.7.12"
 includedir = "0.2.0"
-linefeed = "0.5.0"
-regex = "0.2"
+rustyline = "1.0.0"
 
 [build-dependencies]
 includedir_codegen = "0.2.0"

schala-repl/src/language.rs

@@ -6,21 +6,9 @@ pub struct LLVMCodeString(pub String);
 
 #[derive(Debug, Default, Serialize, Deserialize)]
 pub struct EvalOptions {
-  pub execution_method: ExecutionMethod,
-  pub debug_passes: HashMap<String, PassDebugOptionsDescriptor>,
+  pub debug: DebugOptions,
+  pub execution_method: ExecutionMethod
 }
-
-#[derive(Debug, Hash, PartialEq)]
-pub struct PassDescriptor {
-  pub name: String,
-  pub debug_options: Vec<String>
-}
-
-#[derive(Debug, Serialize, Deserialize)]
-pub struct PassDebugOptionsDescriptor {
-  pub opts: Vec<String>,
-}
-
 #[derive(Debug, Serialize, Deserialize)]
 pub enum ExecutionMethod {
   Compile,
@@ -32,27 +20,67 @@ impl Default for ExecutionMethod {
   }
 }
 
+#[derive(Debug, Default, Serialize, Deserialize)]
+pub struct DebugOptions {
+  pub tokens: bool,
+  pub parse_tree: bool,
+  pub ast: bool,
+  pub type_checking: bool,
+  pub symbol_table: bool,
+  pub evaluation: bool,
+  pub llvm_ir: bool,
+}
+
+#[derive(Debug, Default)]
+pub struct LanguageOutput {
+  output: String,
+  artifacts: Vec<TraceArtifact>,
+  pub failed: bool,
+}
+
+impl LanguageOutput {
+  pub fn add_artifact(&mut self, artifact: TraceArtifact) {
+    self.artifacts.push(artifact);
+  }
+  pub fn add_output(&mut self, output: String) {
+    self.output = output;
+  }
+
+  pub fn to_string(&self) -> String {
+    let mut acc = String::new();
+    for line in self.artifacts.iter() {
+      acc.push_str(&line.debug_output.color(line.text_color).to_string());
+      acc.push_str(&"\n");
+    }
+    acc.push_str(&self.output);
+    acc
+  }
+
+  pub fn print_to_screen(&self) {
+    for line in self.artifacts.iter() {
+      let color = line.text_color;
+      let stage = line.stage_name.color(color).to_string();
+      let output = line.debug_output.color(color).to_string();
+      println!("{}: {}", stage, output);
+    }
+    println!("{}", self.output);
+  }
+}
+
 #[derive(Debug, Default)]
 pub struct UnfinishedComputation {
-  artifacts: Vec<(String, TraceArtifact)>,
-  pub cur_debug_options: Vec<String>,
+  artifacts: HashMap<String, TraceArtifact>,
 }
 
 #[derive(Debug)]
 pub struct FinishedComputation {
-  artifacts: Vec<(String, TraceArtifact)>,
+  artifacts: HashMap<String, TraceArtifact>,
   text_output: Result<String, String>,
 }
 
 impl UnfinishedComputation {
   pub fn add_artifact(&mut self, artifact: TraceArtifact) {
-    self.artifacts.push((artifact.stage_name.clone(), artifact));
-  }
-  pub fn finish(self, text_output: Result<String, String>) -> FinishedComputation {
-    FinishedComputation {
-      artifacts: self.artifacts,
-      text_output
-    }
+    self.artifacts.insert(artifact.stage_name.clone(), artifact);
   }
   pub fn output(self, output: Result<String, String>) -> FinishedComputation {
     FinishedComputation {
@@ -65,13 +93,14 @@ impl UnfinishedComputation {
 impl FinishedComputation {
   pub fn to_repl(&self) -> String {
     let mut buf = String::new();
-    for (stage, artifact) in self.artifacts.iter() {
-      let color = artifact.text_color;
-      let stage = stage.color(color).bold();
-      let output = artifact.debug_output.color(color);
-      write!(&mut buf, "{}: {}\n", stage, output).unwrap();
+    for stage in ["tokens", "parse_trace", "ast", "symbol_table", "type_check"].iter() {
+      if let Some(artifact) = self.artifacts.get(&stage.to_string()) {
+        let color = artifact.text_color;
+        let stage = stage.color(color).bold();
+        let output = artifact.debug_output.color(color);
+        write!(&mut buf, "{}: {}\n", stage, output).unwrap();
+      }
     }
-
     match self.text_output {
       Ok(ref output) => write!(&mut buf, "{}", output).unwrap(),
       Err(ref err) => write!(&mut buf, "{} {}", "Error: ".red().bold(), err).unwrap(),
@@ -82,11 +111,13 @@ impl FinishedComputation {
     match self.text_output {
       Ok(_) => {
         let mut buf = String::new();
-        for (stage, artifact) in self.artifacts.iter() {
-          let color = artifact.text_color;
-          let stage = stage.color(color).bold();
-          let output = artifact.debug_output.color(color);
-          write!(&mut buf, "{}: {}\n", stage, output).unwrap();
+        for stage in ["tokens", "parse_trace", "ast", "symbol_table", "type_check"].iter() {
+          if let Some(artifact) = self.artifacts.get(&stage.to_string()) {
+            let color = artifact.text_color;
+            let stage = stage.color(color).bold();
+            let output = artifact.debug_output.color(color);
+            write!(&mut buf, "{}: {}\n", stage, output).unwrap();
+          }
         }
         if buf == "" { None } else { Some(buf) }
       },
@@ -106,7 +137,6 @@ impl TraceArtifact {
   pub fn new(stage: &str, debug: String) -> TraceArtifact {
     let color = match stage {
       "parse_trace"  | "ast" => "red",
-      "ast_reducing" => "red",
       "tokens" => "green",
       "type_check" => "magenta",
       _ => "blue",
@@ -127,70 +157,25 @@ impl TraceArtifact {
 }
 
 pub trait ProgrammingLanguageInterface {
-  fn execute_pipeline(&mut self, _input: &str, _eval_options: &EvalOptions) -> FinishedComputation {
-    FinishedComputation { artifacts: vec![], text_output: Err(format!("Execution pipeline not done")) }
+  /* old */
+  fn evaluate_in_repl(&mut self, _: &str, _: &EvalOptions) -> LanguageOutput {
+    LanguageOutput { output: format!("Defunct"), artifacts: vec![], failed: false }
+  }
+  /* old */
+
+  fn new_execute(&mut self, input: &str, _options: &EvalOptions) -> FinishedComputation {
+    FinishedComputation { artifacts: HashMap::new(), text_output: Err(format!("NOT DONE")) }
   }
 
+  fn execute(&mut self, _input: &str, _eval_options: &EvalOptions) -> FinishedComputation {
+    FinishedComputation { artifacts: HashMap::new(), text_output: Err(format!("REPL evaluation not implemented")) }
+  }
   fn get_language_name(&self) -> String;
   fn get_source_file_suffix(&self) -> String;
-  fn get_passes(&self) -> Vec<PassDescriptor> {
-    vec![]
-  }
-  fn handle_custom_interpreter_directives(&mut self, _commands: &Vec<&str>) -> Option<String> {
+  fn handle_custom_interpreter_directives(&mut self, commands: &Vec<&str>) -> Option<String> {
     None
   }
   fn custom_interpreter_directives_help(&self) -> String {
     format!(">> No custom interpreter directives specified <<")
   }
 }
-
-/* a pass_chain function signature looks like: 
- * fn(&mut ProgrammingLanguageInterface, A, Option<&mut DebugHandler>) -> Result<B, String>
- *
- * TODO use some kind of failure-handling library to make this better
- */
-
-#[macro_export]
-macro_rules! pass_chain {
-  ($state:expr, $options:expr; $($pass:path), *) => {
-    |text_input| {
-      let mut comp = UnfinishedComputation::default();
-      pass_chain_helper! { ($state, comp, $options); text_input $(, $pass)* }
-    }
-  };
-}
-
-#[macro_export]
-macro_rules! pass_chain_helper {
-  (($state:expr, $comp:expr, $options:expr); $input:expr, $pass:path $(, $rest:path)*) => {
-    {
-      use schala_repl::PassDebugOptionsDescriptor;
-      let pass_name = stringify!($pass);
-      let output = {
-        let ref debug_map = $options.debug_passes;
-        let debug_handle = match debug_map.get(pass_name) {
-          Some(PassDebugOptionsDescriptor { opts }) => {
-            let ptr = &mut $comp;
-            ptr.cur_debug_options = opts.clone();
-            Some(ptr)
-          }
-          _ => None
-        };
-        $pass($state, $input, debug_handle)
-      };
-      match output {
-        Ok(result) => pass_chain_helper! { ($state, $comp, $options); result $(, $rest)* },
-        Err(err) => {
-          $comp.output(Err(format!("Pass {} failed with {:?}", pass_name, err)))
-        }
-      }
-    }
-  };
-  // Done
-  (($state:expr, $comp:expr, $options:expr); $final_output:expr) => {
-    {
-      let final_output: FinishedComputation = $comp.finish(Ok($final_output));
-      final_output
-    }
-  };
-}

schala-repl/src/lib.rs

@@ -3,7 +3,7 @@
 #![feature(plugin)]
 #![plugin(rocket_codegen)]
 extern crate getopts;
-extern crate linefeed;
+extern crate rustyline;
 extern crate itertools;
 extern crate colored;
 
@@ -22,8 +22,9 @@ use std::process::exit;
 use std::default::Default;
 use std::fmt::Write as FmtWrite;
 
-use colored::*;
-use itertools::Itertools;
+use rustyline::error::ReadlineError;
+use rustyline::Editor;
+use self::colored::*;
 
 mod language;
 mod webapp;
@@ -33,9 +34,7 @@ const VERSION_STRING: &'static str = "0.1.0";
 
 include!(concat!(env!("OUT_DIR"), "/static.rs"));
 
-pub use language::{LLVMCodeString, ProgrammingLanguageInterface, EvalOptions,
-  ExecutionMethod, TraceArtifact, FinishedComputation, UnfinishedComputation, PassDebugOptionsDescriptor, PassDescriptor};
-
+pub use language::{LLVMCodeString, ProgrammingLanguageInterface, EvalOptions, ExecutionMethod, TraceArtifact, LanguageOutput, FinishedComputation, UnfinishedComputation};
 pub type PLIGenerator = Box<Fn() -> Box<ProgrammingLanguageInterface> + Send + Sync>;
 
 pub fn repl_main(generators: Vec<PLIGenerator>) {
@@ -64,12 +63,12 @@ pub fn repl_main(generators: Vec<PLIGenerator>) {
   }
 
   let mut options = EvalOptions::default();
-  let debug_passes = if let Some(opts) = option_matches.opt_str("debug") {
-    let output: Vec<String> = opts.split_terminator(",").map(|s| s.to_string()).collect();
-    output
-  } else {
-    vec![]
-  };
+  if let Some(ref ltrs) = option_matches.opt_str("debug") {
+    options.debug.tokens = ltrs.contains("l");
+    options.debug.ast = ltrs.contains("a");
+    options.debug.parse_tree = ltrs.contains("r");
+    options.debug.symbol_table = ltrs.contains("s");
+  }
 
   let language_names: Vec<String> = languages.iter().map(|lang| {lang.get_language_name()}).collect();
   let initial_index: usize =
@@ -89,12 +88,12 @@ pub fn repl_main(generators: Vec<PLIGenerator>) {
     }
     [_, ref filename, _..] => {
 
-      run_noninteractive(filename, languages, options, debug_passes);
+      run_noninteractive(filename, languages, options);
     }
   };
 }
 
-fn run_noninteractive(filename: &str, languages: Vec<Box<ProgrammingLanguageInterface>>, mut options: EvalOptions, debug_passes: Vec<String>) {
+fn run_noninteractive(filename: &str, languages: Vec<Box<ProgrammingLanguageInterface>>, options: EvalOptions) {
   let path = Path::new(filename);
   let ext = path.extension().and_then(|e| e.to_str()).unwrap_or_else(|| {
     println!("Source file lacks extension");
@@ -111,12 +110,6 @@ fn run_noninteractive(filename: &str, languages: Vec<Box<ProgrammingLanguageInte
 
   source_file.read_to_string(&mut buffer).unwrap();
 
-  for pass in debug_passes.into_iter() {
-    if let Some(_) = language.get_passes().iter().find(|desc| desc.name == pass) {
-      options.debug_passes.insert(pass, PassDebugOptionsDescriptor { opts: vec![] });
-    }
-  }
-
   match options.execution_method {
     ExecutionMethod::Compile => {
       /*
@@ -126,136 +119,35 @@ fn run_noninteractive(filename: &str, languages: Vec<Box<ProgrammingLanguageInte
       panic!("Not ready to go yet");
     },
     ExecutionMethod::Interpret => {
-      let output = language.execute_pipeline(&buffer, &options);
+      let output = language.execute(&buffer, &options);
       output.to_noninteractive().map(|text| println!("{}", text));
     }
   }
 }
 
-#[derive(Clone)]
-enum CommandTree {
-  Terminal(String, Option<String>),
-  NonTerminal(String, Vec<CommandTree>, Option<String>),
-  Top(Vec<CommandTree>),
-}
-
-impl CommandTree {
-  fn term(s: &str, help: Option<&str>) -> CommandTree {
-    CommandTree::Terminal(s.to_string(), help.map(|x| x.to_string()))
-  }
-  fn get_cmd(&self) -> String {
-    match self {
-      CommandTree::Terminal(s, _) => s.to_string(),
-      CommandTree::NonTerminal(s, _, _) => s.to_string(),
-      CommandTree::Top(_) => "".to_string(),
-    }
-  }
-  fn get_help(&self) -> String {
-    match self {
-      CommandTree::Terminal(_, h) => h.as_ref().map(|h| h.clone()).unwrap_or(format!("")),
-      CommandTree::NonTerminal(_, _, h) => h.as_ref().map(|h| h.clone()).unwrap_or(format!("")),
-      CommandTree::Top(_) => "".to_string(),
-    }
-  }
-  fn get_children(&self) -> Vec<String> {
-    match self {
-      CommandTree::Terminal(_, _) => vec![],
-      CommandTree::NonTerminal(_, children, _) => children.iter().map(|x| x.get_cmd()).collect(),
-      CommandTree::Top(children) => children.iter().map(|x| x.get_cmd()).collect(),
-    }
-  }
-}
-
-struct TabCompleteHandler {
-  sigil: char,
-  top_level_commands: CommandTree,
-}
-
-use linefeed::complete::{Completion, Completer};
-use linefeed::terminal::Terminal;
-
-impl TabCompleteHandler {
-  fn new(sigil: char, top_level_commands: CommandTree) -> TabCompleteHandler {
-    TabCompleteHandler {
-      top_level_commands,
-      sigil,
-    }
-  }
-}
-
-impl<T: Terminal> Completer<T> for TabCompleteHandler {
-  fn complete(&self, word: &str, prompter: &linefeed::prompter::Prompter<T>, start: usize, _end: usize) -> Option<Vec<Completion>> {
-    let line = prompter.buffer();
-
-    if line.starts_with(&format!("{}", self.sigil)) {
-      let mut words = line[1..(if start == 0 { 1 } else { start })].split_whitespace();
-      let mut completions = Vec::new();
-      let mut command_tree: Option<&CommandTree> = Some(&self.top_level_commands);
-
-      loop {
-        match words.next() {
-          None => {
-            let top = match command_tree {
-              Some(CommandTree::Top(_)) => true,
-              _ => false
-            };
-            let word = if top { word.get(1..).unwrap() } else { word };
-            for cmd in command_tree.map(|x| x.get_children()).unwrap_or(vec![]).into_iter() {
-              if cmd.starts_with(word) {
-                completions.push(Completion {
-                    completion: format!("{}{}", if top { ":" } else { "" }, cmd),
-                    display: Some(cmd.clone()),
-                    suffix: linefeed::complete::Suffix::Some(' ')
-                })
-              }
-            }
-            break;
-          },
-          Some(s) => {
-            let new_ptr: Option<&CommandTree> = command_tree.and_then(|cm| match cm {
-              CommandTree::Top(children) => children.iter().find(|c| c.get_cmd() == s),
-              CommandTree::NonTerminal(_, children, _) => children.iter().find(|c| c.get_cmd() == s),
-              CommandTree::Terminal(_, _) => None,
-            });
-            command_tree = new_ptr;
-          }
-        }
-      }
-      Some(completions)
-    } else {
-      None
-    }
-  }
-}
-
 struct Repl {
   options: EvalOptions,
   languages: Vec<Box<ProgrammingLanguageInterface>>,
   current_language_index: usize,
   interpreter_directive_sigil: char,
-  line_reader: linefeed::interface::Interface<linefeed::terminal::DefaultTerminal>,
+  console: rustyline::Editor<()>,
 }
 
 impl Repl {
   fn new(languages: Vec<Box<ProgrammingLanguageInterface>>, initial_index: usize) -> Repl {
-    use linefeed::Interface;
     let i = if initial_index < languages.len() { initial_index } else { 0 };
 
-    let line_reader = Interface::new("schala-repl").unwrap();
+    let console = Editor::<()>::new();
 
     Repl {
       options: Repl::get_options(),
       languages: languages,
       current_language_index: i,
       interpreter_directive_sigil: ':',
-      line_reader
+      console
     }
   }
 
-  fn get_cur_language(&self) -> &ProgrammingLanguageInterface {
-    self.languages[self.current_language_index].as_ref()
-  }
-
   fn get_options() -> EvalOptions {
     File::open(".schala_repl")
       .and_then(|mut file| {
@@ -283,33 +175,27 @@ impl Repl {
   }
 
   fn run(&mut self) {
-    use linefeed::ReadResult;
-
     println!("Schala MetaInterpreter version {}", VERSION_STRING);
     println!("Type {}help for help with the REPL", self.interpreter_directive_sigil);
 
-    self.line_reader.load_history(".schala_history").unwrap_or(());
+    self.console.get_history().load(".schala_history").unwrap_or(());
 
     loop {
       let language_name = self.languages[self.current_language_index].get_language_name();
-      let directives = self.get_directives();
-      let tab_complete_handler = TabCompleteHandler::new(self.interpreter_directive_sigil, directives);
-      self.line_reader.set_completer(std::sync::Arc::new(tab_complete_handler));
-
       let prompt_str = format!("{} >> ", language_name);
-      self.line_reader.set_prompt(&prompt_str);
 
-      match self.line_reader.read_line() {
+      match self.console.readline(&prompt_str) {
+        Err(ReadlineError::Eof) | Err(ReadlineError::Interrupted) => break,
         Err(e) => {
           println!("Terminal read error: {}", e);
         },
-        Ok(ReadResult::Eof) => break,
-        Ok(ReadResult::Signal(_)) => break,
-        Ok(ReadResult::Input(ref input)) => {
-          self.line_reader.add_history_unique(input.to_string());
+        Ok(ref input) => {
           let output = match input.chars().nth(0) {
             Some(ch) if ch == self.interpreter_directive_sigil => self.handle_interpreter_directive(input),
-            _ => Some(self.input_handler(input)),
+            _ => {
+              self.console.get_history().add(input);
+              Some(self.input_handler(input))
+            }
           };
           if let Some(o) = output {
             println!("=> {}", o);
@@ -317,53 +203,17 @@ impl Repl {
         }
       }
     }
-    self.line_reader.save_history(".schala_history").unwrap_or(());
+    self.console.get_history().save(".schala_history").unwrap_or(());
     self.save_options();
     println!("Exiting...");
   }
 
   fn input_handler(&mut self, input: &str) -> String {
     let ref mut language = self.languages[self.current_language_index];
-    let interpreter_output = language.execute_pipeline(input, &self.options);
+    let interpreter_output = language.new_execute(input, &self.options);
     interpreter_output.to_repl()
   }
 
-  fn get_directives(&self) -> CommandTree {
-    let ref passes = self.get_cur_language().get_passes();
-
-    let passes_directives: Vec<CommandTree> = passes.iter()
-      .map(|pass_descriptor| {
-        let name = &pass_descriptor.name;
-        if pass_descriptor.debug_options.len() == 0 {
-          CommandTree::term(name, None)
-        } else {
-          let sub_opts: Vec<CommandTree> = pass_descriptor.debug_options.iter()
-            .map(|o| CommandTree::term(o, None)).collect();
-          CommandTree::NonTerminal(
-            name.clone(),
-            sub_opts,
-            None
-          )
-        }
-      }).collect();
-
-    CommandTree::Top(vec![
-      CommandTree::term("exit", Some("exit the REPL")),
-      CommandTree::term("quit", Some("exit the REPL")),
-      CommandTree::term("help", Some("Print this help message")),
-      CommandTree::NonTerminal(format!("debug"), vec![
-        CommandTree::term("passes", None),
-        CommandTree::NonTerminal(format!("show"), passes_directives.clone(), None),
-        CommandTree::NonTerminal(format!("hide"), passes_directives.clone(), None),
-      ], Some(format!("show or hide pass info for a given pass, or display the names of all passes"))),
-      CommandTree::NonTerminal(format!("lang"), vec![
-        CommandTree::term("next", None),
-        CommandTree::term("prev", None),
-        CommandTree::NonTerminal(format!("go"), vec![], None)//TODO
-      ], Some(format!("switch between languages, or go directly to a langauge by name"))),
-    ])
-  }
-
   fn handle_interpreter_directive(&mut self, input: &str) -> Option<String> {
     let mut iter = input.chars();
     iter.next();
@@ -417,72 +267,52 @@ impl Repl {
       "help" =>  {
         let mut buf = String::new();
         let ref lang = self.languages[self.current_language_index];
-        let directives = match self.get_directives() {
-            CommandTree::Top(children) => children,
-            _ => panic!("Top-level CommandTree not Top")
-        };
 
         writeln!(buf, "MetaInterpreter options").unwrap();
         writeln!(buf, "-----------------------").unwrap();
-
-        for directive in directives {
-          let trailer = " ";
-          writeln!(buf, "{}{}- {}", directive.get_cmd(), trailer, directive.get_help()).unwrap();
-        }
-
-        writeln!(buf, "").unwrap();
+        writeln!(buf, "exit | quit - exit the REPL").unwrap();
+        writeln!(buf, "lang [prev|next|go <name> |show] - toggle to previous or next language, go to a specific language by name, or show all languages").unwrap();
         writeln!(buf, "Language-specific help for {}", lang.get_language_name()).unwrap();
         writeln!(buf, "-----------------------").unwrap();
         writeln!(buf, "{}", lang.custom_interpreter_directives_help()).unwrap();
         Some(buf)
       },
-      "debug" => self.handle_debug(commands),
+      "set" => {
+        let show = match commands.get(1) {
+          Some(&"show") => true,
+          Some(&"hide") => false,
+          Some(e) => {
+            return Some(format!("Bad `set` argument: {}", e));
+          }
+          None => {
+            return Some(format!("`set` - valid arguments `show {{option}}`, `hide {{option}}`"));
+          }
+        };
+        match commands.get(2) {
+          Some(&"tokens") => self.options.debug.tokens = show,
+          Some(&"parse") => self.options.debug.parse_tree = show,
+          Some(&"ast") => self.options.debug.ast = show,
+          Some(&"symbols") => self.options.debug.symbol_table = show,
+          Some(&"llvm") => self.options.debug.llvm_ir = show,
+          Some(e) => return Some(format!("Bad `show`/`hide` argument: {}", e)),
+          None => return Some(format!("`show`/`hide` requires an argument")),
+        };
+        None
+      },
+      "options" => {
+        let ref d = self.options.debug;
+        let tokens = if d.tokens { "true".green() } else { "false".red() };
+        let parse_tree = if d.parse_tree { "true".green() } else { "false".red() };
+        let ast = if d.ast { "true".green() } else { "false".red() };
+        let symbol_table = if d.symbol_table { "true".green() } else { "false".red() };
+        Some(format!(r#"Debug:
+tokens: {}, parse: {}, ast: {}, symbols: {}"#, tokens, parse_tree, ast, symbol_table))
+      },
       e => self.languages[self.current_language_index]
         .handle_custom_interpreter_directives(&commands)
         .or(Some(format!("Unknown command: {}", e)))
     }
   }
-  fn handle_debug(&mut self, commands: Vec<&str>) -> Option<String> {
-    let passes = self.get_cur_language().get_passes();
-    match commands.get(1) {
-      Some(&"passes") => Some(
-        passes.into_iter()
-        .map(|desc| {
-          if self.options.debug_passes.contains_key(&desc.name) {
-            let color = "green";
-            format!("*{}", desc.name.color(color))
-          } else {
-            desc.name 
-          }
-        })
-        .intersperse(format!(" -> "))
-        .collect()),
-      b @ Some(&"show") | b @ Some(&"hide") => {
-        let show = b == Some(&"show");
-        let debug_pass: String = match commands.get(2) {
-          Some(s) => s.to_string(),
-          None => return Some(format!("Must specify a stage to debug")),
-        };
-        let pass_opt = commands.get(3);
-        if let Some(desc) = passes.iter().find(|desc| desc.name == debug_pass) {
-          let mut opts = vec![];
-          if let Some(opt) = pass_opt {
-            opts.push(opt.to_string());
-          }
-          let msg = format!("{} debug for pass {}", if show { "Enabling" } else { "Disabling" }, debug_pass);
-          if show {
-            self.options.debug_passes.insert(desc.name.clone(), PassDebugOptionsDescriptor { opts });
-          } else {
-            self.options.debug_passes.remove(&desc.name);
-          }
-          Some(msg)
-        } else {
-          Some(format!("Couldn't find stage: {}", debug_pass))
-        }
-      },
-      _ => Some(format!("Unknown debug command"))
-    }
-  }
 }
 
 /*

schala-repl/src/webapp.rs

@@ -35,8 +35,8 @@ struct Output {
 fn interpreter_input(input: Json<Input>, generators: State<Vec<PLIGenerator>>) -> Json<Output> {
   let schala_gen = generators.get(0).unwrap();
   let mut schala: Box<ProgrammingLanguageInterface> = schala_gen();
-  let code_output = schala.execute_pipeline(&input.source, &EvalOptions::default());
-  Json(Output { text: code_output.to_repl() })
+  let code_output = schala.evaluate_in_repl(&input.source, &EvalOptions::default());
+  Json(Output { text: code_output.to_string() })
 }
 
 pub fn web_main(language_generators: Vec<PLIGenerator>) {

source_files/schala/fizzbuzz.schala

@@ -1,12 +0,0 @@
-
-for n <- 1..=100 {
-  if n % 15 == 0 {
-    print("FizzBuzz")
-  } else if n % 5 == 0 {
-    print("Buzz")
-  } else if n % 3 == 0 {
-    print("Fizz")
-  } else {
-    print(n.to_string())
-  }
-}

source_files/schala/syntax_playground.schala

@@ -1,114 +0,0 @@
-
-fn main() {
-
-//comments are C-style
-/* nested comments /* are cool */ */
-
-}
-
-@annotations are with @-
-
-// variable expressions
-  var a: I32 = 20
-  const b: String = 20
-
-  there(); can(); be(); multiple(); statements(); per_line();
-
-  //string interpolation
-  const yolo = "I have ${a + b} people in my house"
-
-  // let expressions ??? not sure if I want this
-  let a = 10, b = 20, c = 30 in a + b + c
-
-  //list literal
-  const q = [1,2,3,4]
-
-  //lambda literal 
-  q.map({|item| item * 100 })
-
-  fn yolo(a: MyType, b: YourType): ReturnType<Param1, Param2> {
-    if a == 20 {
-      return "early"
-    }
-    var sex = 20
-    sex
-  }
-
-
-/* for/while loop topics */
-
-   //infinite loop
-   while {
-     if x() { break }
-     ...
-   }
-
-
-   //conditional loop
-   while conditionHolds() {
-      ...
-   }
-
-
-  //iteration over a variable
-  for i <- [1..1000]  {
-
-  } //return type is return type of block
-
-
-  //monadic decomposition
-  for {
-    a <- maybeInt();
-    s <- foo() 
-  } return {
-    a + s
-  } //return type is Monad<return type of block>
-
-/* end of for loops */
-
-
-
-/* conditionals/pattern matching */
-
-// "is" operator for "does this pattern match"
-
-x is Some(t) // type bool
-
-if x {
-  is Some(t) => {
-  },
-  is None => {
-
-  }
-}
-
-
- //syntax is, I guess, for <expr> <brace-block>, where <expr> is a bool, or a <arrow-expr>
-
- // type level alises
- typealias <name> = <other type> #maybe thsi should be 'alias'?
-
-/*
-what if type A = B meant that you could had to create A's with A(B), but when you used A's the interface was exactly like B's?
- maybe introduce a 'newtype' keyword for this
- */
-
- //declaring types of all stripes
- type MyData = { a: i32, b: String }
- type MyType = MyType
- type Option<a> = None | Some(a)
- type Signal = Absence | SimplePresence(i32) | ComplexPresence {a: i32, b: MyCustomData}
-
- //traits
- 
- trait Bashable { }
- trait Luggable {
-  fn lug(self, a: Option<Self>)
- }
-
-}
-
-
-// lambdas
-// ruby-style not rust-style
-const a: X -> Y -> Z = {|x,y|  }

source_files/schala/test.schala

@@ -1,17 +1,105 @@
 
-println(sua(4))
+fn main() {
+
+//comments are C-style
+/* nested comments /* are cool */ */
 
-fn sua(x): Int {
-  x + 10
 }
 
+@annotations are with @-
 
-//const a = getline()
+// variable expressions
+  var a: I32 = 20
+  const b: String = 20
+
+  there(); can(); be(); multiple(); statements(); per_line();
+
+  //string interpolation
+  const yolo = "I have ${a + b} people in my house"
+
+  // let expressions ??? not sure if I want this
+  let a = 10, b = 20, c = 30 in a + b + c
+
+  //list literal
+  const q = [1,2,3,4]
+
+  //lambda literal 
+  q.map({|item| item * 100 })
+
+  fn yolo(a: MyType, b: YourType): ReturnType<Param1, Param2> {
+    if a == 20 {
+      return "early"
+    }
+    var sex = 20
+    sex
+  }
+
+
+  for {
+  //infinite loop
+  }
+
+  //iteration over a variable
+  for i <- [1..1000]  {
+
+  } //return type is return type of block
+
+  //while loop
+  for a != 3 || fuckTard() {
+    break
+  } //return type is return type of block
+
+  //monadic decomposition
+  for {
+    a <- maybeInt();
+    s <- foo() 
+  } return {
+    a + s
+  } //return type is Monad<return type of block>
+
+  // let statements too!!
+  for (a = 20
+  b = fuck) {
+    a + b
+  }
+
+
+  // pattern-matching
+  match <expr> {
+    Some(a) => {
+
+    },
+    None => {
+
+    },
+  }
+
+ //syntax is, I guess, for <expr> <brace-block>, where <expr> is a bool, or a <arrow-expr>
+
+ // type level alises
+ typealias <name> = <other type> #maybe thsi should be 'alias'?
 
 /*
-if a == "true" {
-  println("You typed true")
-} else {
-  println("You typed something else")
+what if type A = B meant that you could had to create A's with A(B), but when you used A's the interface was exactly like B's?
+ maybe introduce a 'newtype' keyword for this
+ */
+
+ //declaring types of all stripes
+ type MyData = { a: i32, b: String }
+ type MyType = MyType
+ type Option<a> = None | Some(a)
+ type Signal = Absence | SimplePresence(i32) | ComplexPresence {a: i32, b: MyCustomData}
+
+ //traits
+ 
+ trait Bashable { }
+ trait Luggable {
+  fn lug(self, a: Option<Self>)
+ }
+
 }
-*/
+
+
+// lambdas
+// ruby-style not rust-style
+const a: X -> Y -> Z = {|x,y|  }

source_files/schala/very_simple.schala

@@ -1,12 +0,0 @@
-
-const c = 10
-
-fn add(a, b) {
-  const c = a + b
-  c
-}
-
-var b = 20
-
-println(add(1,2))
-println(c + b)