From 8d6fea942f691297c80b1aa03efbc17533f7248b Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Sun, 13 May 2018 17:24:21 -0700
Subject: [PATCH] Handle function definition before use

And some other ReducedAST - Evaluation niceties
---
 schala-lang/src/ast_reducing.rs | 16 +++++++++++-----
 schala-lang/src/eval.rs         | 23 +++++++++++++++++++++++
 source_files/schala/test.schala |  2 +-
 3 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/schala-lang/src/ast_reducing.rs b/schala-lang/src/ast_reducing.rs
index 4ccf8d6..21f1a00 100644
--- a/schala-lang/src/ast_reducing.rs
+++ b/schala-lang/src/ast_reducing.rs
@@ -8,12 +8,17 @@ 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)]
@@ -111,17 +116,18 @@ impl Expression {
 impl Declaration {
   fn reduce(&self) -> Stmt {
     use self::Declaration::*;
+    use ::parsing::Signature;
     match self {
       Binding {name, constant, expr } => Stmt::Binding { name: name.clone(), constant: *constant, expr: expr.reduce() },
-      FuncDecl(::parsing::Signature { name, params, .. }, statements) => Stmt::Binding {
+      FuncDecl(Signature { name, params, .. }, statements) => Stmt::PreBinding {
         name: name.clone(),
-        constant: true,
-        expr: Expr::Func(Func::UserDefined {
-          name: None,
+        func: Func::UserDefined {
+          name: Some(name.clone()),
           params: params.iter().map(|param| param.0.clone()).collect(),
           body: statements.iter().map(|stmt| stmt.reduce()).collect(),
-        })
+        }
       },
+      TypeDecl(_,_) => Stmt::Noop,
       _ => Stmt::Expr(Expr::UnimplementedSigilValue)
     }
   }
diff --git a/schala-lang/src/eval.rs b/schala-lang/src/eval.rs
index 6273e84..f9dd7c3 100644
--- a/schala-lang/src/eval.rs
+++ b/schala-lang/src/eval.rs
@@ -318,6 +318,12 @@ impl Expr {
 impl<'a> State<'a> {
   pub fn evaluate(&mut self, ast: ReducedAST, repl: bool) -> 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())),
@@ -331,6 +337,20 @@ impl<'a> State<'a> {
     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 } => {
@@ -339,6 +359,7 @@ impl<'a> State<'a> {
         Ok(None)
       },
       Stmt::Expr(expr) => Ok(Some(self.expression(expr)?)),
+      Stmt::PreBinding {..} | Stmt::Noop => Ok(None),
     }
   }
 
@@ -471,6 +492,8 @@ impl<'a> State<'a> {
 
   fn value(&mut self, name: Rc<String>) -> EvalResult<Expr> {
     use self::ValueEntry::*;
+    //TODO add a layer of indirection here to talk to the symbol table first, and only then look up
+    //in the values table
     match self.values.lookup(&name) {
       None => return Err(format!("Value {} not found", *name)),
       Some(lookup) => match lookup {
diff --git a/source_files/schala/test.schala b/source_files/schala/test.schala
index eab6109..0780446 100644
--- a/source_files/schala/test.schala
+++ b/source_files/schala/test.schala
@@ -1,5 +1,5 @@
 
-println(a(4))
+println(sua(4))
 
 fn sua(x): Int {
   x + 10