Inline parsing of lambdas like half-works

lambda.schala

@@ -1,5 +1,5 @@
 
-(fn(q) { q * 2 })(25)
+(fn(q) { q * 2 }(25))
 
 a = fn(x) { x + 5 }
 a(2)

src/eval.rs

@@ -2,7 +2,7 @@ extern crate take_mut;
 
 use std::collections::HashMap;
 use std::collections::VecDeque;
-use parser::{AST, Statement, Expression, Function};
+use parser::{AST, Statement, Expression, Function, Callable};
 use std::rc::Rc;
 use std::io::{Write, Stdout, BufWriter};
 use std::convert::From;
@@ -12,7 +12,6 @@ use parser::Statement::*;
 
 type Reduction<T> = (T, Option<SideEffect>);
 
-
 #[derive(Debug, Clone)]
 enum ReducedValue {
     StringLiteral(Rc<String>),
@@ -259,7 +258,7 @@ impl<'a> Evaluator<'a> {
                     (self.reduce_binop(op, *left, *right), None) //can assume both arguments are maximally reduced
                 }
             }
-            Call(name, mut args) => {
+            Call(callable, mut args) => {
                 let mut f = true;
                 for arg in args.iter_mut() {
                     if arg.is_reducible() {
@@ -269,9 +268,9 @@ impl<'a> Evaluator<'a> {
                     }
                 }
                 if f {
-                    self.reduce_call(name, args)
+                    self.reduce_call(callable, args)
                 } else {
-                    (Call(name, args), None)
+                    (Call(callable, args), None)
                 }
             }
             While(test, body) => {
@@ -341,18 +340,22 @@ impl<'a> Evaluator<'a> {
         }
     }
 
-    fn reduce_call(&mut self, name: Rc<String>, arguments: Vec<Expression>) -> Reduction<Expression> {
-        if let Some(res) = handle_builtin(&*name, &arguments) {
+    fn reduce_call(&mut self, callable: Callable, arguments: Vec<Expression>) -> Reduction<Expression> {
+        if let Some(res) = handle_builtin(&callable, &arguments) {
             return res;
         }
 
-        println!("Reduce call, name {} args: {:?}", name, arguments);
+        println!("Reduce call, callable {:?} args: {:?}", callable, arguments);
 
-        let function = match self.lookup_binding(&*name) {
+        let function = match callable {
+            Callable::Lambda(func) => func.clone(),
+            Callable::NamedFunction(name) => {
+                match self.lookup_binding(&*name) {
                     Some(ReducedValue::Lambda(func)) => func,
                     _ => return (Null, None),
+                }
+            }
         };
-
         if function.prototype.parameters.len() != arguments.len() {
             return (Null, None);
         }
@@ -376,7 +379,12 @@ impl<'a> Evaluator<'a> {
     }
 }
 
-fn handle_builtin(name: &str, arguments: &Vec<Expression>) -> Option<Reduction<Expression>> {
+fn handle_builtin(callable: &Callable, arguments: &Vec<Expression>) -> Option<Reduction<Expression>> {
+    let name: &str = match *callable {
+        Callable::NamedFunction(ref name) => *&name,
+        _ => return None,
+    };
+
     match name {
         "print" => {
             let mut s = String::new();

src/parser.rs

@@ -18,11 +18,13 @@ use std::convert::From;
 // primary_expression :=  Number | String | identifier_expr | paren_expr | conditional_expr |
 //                        while_expr | lambda_expr
 // identifier_expr := call_expression | Variable
+// call_expr := Identifier LParen exprlist RParen
 // while_expr := WHILE primary_expression LCurlyBrace (expression delimiter)* RCurlyBrace
 // paren_expr := LParen expression RParen
-// call_expr := Identifier LParen exprlist RParen
 // conditional_expr := IF expression LCurlyBrace (expression delimiter)* RCurlyBrace (LCurlyBrace (expresion delimiter)* RCurlyBrace)?
 // lambda_expr := FN LParen identlist RParen LCurlyBrace (expression delimiter)* RCurlyBrace
+//                lambda_call
+// lambda_call := ε | LParen exprlist RParen
 // op := '+', '-', etc.
 //
 
@@ -63,13 +65,19 @@ pub enum Expression {
     Number(f64),
     Variable(Rc<String>),
     BinExp(Rc<String>, Box<Expression>, Box<Expression>),
-    Call(Rc<String>, Vec<Expression>),
+    Call(Callable, Vec<Expression>),
     Conditional(Box<Expression>, Box<Expression>, Option<Box<Expression>>),
     Lambda(Function),
     Block(VecDeque<Expression>),
     While(Box<Expression>, Vec<Expression>),
 }
 
+#[derive(Clone, Debug)]
+pub enum Callable {
+    NamedFunction(Rc<String>),
+    Lambda(Function),
+}
+
 impl fmt::Display for Expression {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         use self::Expression::*;
@@ -426,7 +434,14 @@ impl Parser {
             prototype: prototype,
             body: body,
         };
-        Ok(Lambda(function))
+
+        match self.peek() {
+            Some(LParen) => {
+                let args = try!(self.call_expr());
+                Ok(Call(Callable::Lambda(function), args))
+            },
+            _ => Ok(Lambda(function))
+        }
     }
 
     fn while_expr(&mut self) -> ParseResult<Expression> {
@@ -481,7 +496,7 @@ impl Parser {
         let expr = match self.peek() {
             Some(LParen) => {
                 let args = try!(self.call_expr());
-                Expression::Call(name, args)
+                Expression::Call(Callable::NamedFunction(name), args)
             }
             __ => Expression::Variable(name),
         };