From 5953d9d81563737f611fe783b9360980229267a0 Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Mon, 5 Nov 2018 19:10:34 -0800
Subject: [PATCH] type annotations on lambdas

---
 schala-lang/language/src/ast.rs     |  1 +
 schala-lang/language/src/parsing.rs | 44 ++++++++++++++++-------------
 2 files changed, 26 insertions(+), 19 deletions(-)

diff --git a/schala-lang/language/src/ast.rs b/schala-lang/language/src/ast.rs
index 4d04560..973389d 100644
--- a/schala-lang/language/src/ast.rs
+++ b/schala-lang/language/src/ast.rs
@@ -111,6 +111,7 @@ pub enum ExpressionType {
   },
   Lambda {
     params: Vec<FormalParam>,
+    type_anno: Option<TypeIdentifier>,
     body: Block,
   },
   ListLiteral(Vec<Expression>),
diff --git a/schala-lang/language/src/parsing.rs b/schala-lang/language/src/parsing.rs
index 7bce092..8e2eba8 100644
--- a/schala-lang/language/src/parsing.rs
+++ b/schala-lang/language/src/parsing.rs
@@ -188,7 +188,7 @@ typed_identifier := IDENTIFIER type_anno
 func_declaration := func_signature func_body
 func_body := ε | nonempty_func_body
 nonempty_func_body := '{' (statement delimiter)* '}'
-func_signature := 'fn' func_name formal_param_list func_body
+func_signature := 'fn' func_name formal_param_list type_anno+
 func_name := IDENTIFIER | operator
 formal_param_list := '(' (formal_param ',')* ')'
 formal_param := IDENTIFIER type_anno+
@@ -227,7 +227,7 @@ primary := literal | paren_expr | if_expr | for_expr | while_expr | identifier_e
 /* Primary Expressions */
 
 list_expr := '[' (expression, ',')* ']'
-lambda_expr := '\' formal_param_list nonempty_func_body
+lambda_expr := '\' formal_param_list type_anno+ nonempty_func_body 
 paren_expr := LParen paren_inner RParen
 paren_inner := (expression ',')*
 identifier_expr := named_struct | IDENTIFIER
@@ -639,22 +639,12 @@ impl Parser {
   fn lambda_expr(&mut self) -> ParseResult<Expression> {
     expect!(self, Backslash);
     let params = self.formal_param_list()?; //TODO make this allow some more concise syntaxes
+    let type_anno = match self.peek() {
+      Colon => Some(self.type_anno()?),
+      _ => None,
+    };
     let body = self.nonempty_func_body()?;
-    /*
-    let mut body = Vec::new();
-    loop {
-      match self.peek() {
-        EOF | RCurlyBrace => break,
-        Newline | Semicolon => {
-          self.next();
-          continue;
-        },
-        _ => body.push(self.statement()?),
-      }
-    }
-    expect!(self, RCurlyBrace);
-    */
-    Ok(Expression(ExpressionType::Lambda { params, body }, None)) //TODO need to handle types somehow
+    Ok(Expression(ExpressionType::Lambda { params, type_anno, body }, None)) //TODO need to handle types somehow
   }
 
   #[recursive_descent_method]
@@ -1483,20 +1473,36 @@ fn a(x) {
   #[test]
   fn parsing_lambdas() {
     parse_test! { r#"\(x) { x + 1}"#, single_expr!(
-      Lambda { params: vec![(rc!(x), None)], body: vec![exst!("+", val!("x"), NatLiteral(1))] }
+      Lambda { params: vec![(rc!(x), None)], type_anno: None, body: vec![exst!("+", val!("x"), NatLiteral(1))] }
     ) }
 
     parse_test!(r#"\  (x: Int, y) { a;b;c;}"#, AST(vec![
       exprstatement!(Lambda {
         params: vec![(rc!(x), Some(ty!("Int"))), (rc!(y), None)],
+        type_anno: None,
         body: vec![exst!(val!("a")), exst!(val!("b")), exst!(val!("c"))]
       })
     ]));
 
     parse_test!(r#"\(x){y}(1)"#, AST(vec![
       exprstatement!(Call { f: bx!(ex!(
-        Lambda { params: vec![(rc!(x), None)], body: vec![exprstatement!(val!("y"))] })),
+        Lambda { 
+          params: vec![(rc!(x), None)],
+          type_anno: None,
+          body: vec![exprstatement!(val!("y"))] }
+        )),
         arguments: vec![ex!(NatLiteral(1))] })]));
+
+    parse_test! {
+      r#"\(x: Int): String { "q" }"#,
+      AST(vec![
+      exprstatement!(Lambda {
+        params: vec![(rc!(x), Some(ty!("Int")))],
+        type_anno: Some(ty!("String")),
+        body: vec![exprstatement!(StringLiteral(rc!(q)))]
+      })
+      ])
+    }
   }
 
   #[test]