From 08ca48b2ba268c88d4b03b3ba37d9ecb0cd70a53 Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Sun, 4 Mar 2018 02:11:22 -0800
Subject: [PATCH] lambdas

---
 source_files/test.schala   |  7 ++++++
 src/schala_lang/parsing.rs | 48 ++++++++++++++++++++++++++++++++++++--
 2 files changed, 53 insertions(+), 2 deletions(-)

diff --git a/source_files/test.schala b/source_files/test.schala
index d223eff..d9ab285 100644
--- a/source_files/test.schala
+++ b/source_files/test.schala
@@ -96,3 +96,10 @@ fn main() {
  }
 
 }
+
+
+# lambdas
+#
+|x,y| { }() #is probably fine
+const a = |x: Type, y|: RetType { <statementblock> }
+const a: X -> Y -> Z = |x,y| { }
diff --git a/src/schala_lang/parsing.rs b/src/schala_lang/parsing.rs
index b5b713d..36192ef 100644
--- a/src/schala_lang/parsing.rs
+++ b/src/schala_lang/parsing.rs
@@ -54,7 +54,9 @@ expression := precedence_expr type_anno+
 precedence_expr := prefix_expr
 prefix_expr := prefix_op primary
 prefix_op := '+' | '-' | '!' | '~'
-primary := literal | paren_expr | if_expr | match_expr | for_expr | identifier_expr
+primary := literal | paren_expr | if_expr | match_expr | for_expr | identifier_expr | curly_brace_expr
+curly_brace_expr := lambda_expr | anonymous_struct //TODO
+lambda_expr := '{' '|' (formal_param ',')* '|' (type_anno)* (statement)* '}'
 paren_expr := LParen paren_inner RParen
 paren_inner := (expression ',')*
 identifier_expr := named_struct | call_expr | index_expr | IDENTIFIER
@@ -63,6 +65,7 @@ literal := 'true' | 'false' | number_literal | STR_LITERAL
 named_struct := IDENTIFIER record_block
 record_block :=  '{' (record_entry, ',')* | '}' //TODO support anonymus structs, update syntax
 record_entry := IDENTIFIER ':' expression
+anonymous_struct := TODO
 
 if_expr := 'if' expression block else_clause
 else_clause := ε | 'else' block
@@ -246,7 +249,11 @@ pub enum ExpressionType {
   },
   IfExpression(Box<Expression>, Vec<Statement>, Option<Vec<Statement>>),
   MatchExpression(Box<Expression>, Vec<MatchArm>),
-  ForExpression
+  ForExpression,
+  Lambda {
+    params: Vec<FormalParam>,
+    body: Vec<Statement>,
+  },
 }
 
 #[derive(Debug, PartialEq, Clone)]
@@ -578,6 +585,7 @@ impl Parser {
 
   parse_method!(primary(&mut self) -> ParseResult<Expression> {
     match self.peek() {
+      LCurlyBrace => self.curly_brace_expr(),
       LParen => self.paren_expr(),
       Keyword(Kw::If) => self.if_expr(),
       Keyword(Kw::Match) => self.match_expr(),
@@ -587,6 +595,28 @@ impl Parser {
     }
   });
 
+  parse_method!(curly_brace_expr(&mut self) -> ParseResult<Expression> {
+    self.lambda_expr()
+  });
+
+  parse_method!(lambda_expr(&mut self) -> ParseResult<Expression> {
+    expect!(self, LCurlyBrace, "{");
+    let params = delimited!(self, Pipe, '|', formal_param, Comma, Pipe, '|');
+    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
+  });
+
   parse_method!(paren_expr(&mut self) -> ParseResult<Expression> {
     use self::ExpressionType::*;
     let old_struct_value = self.restrictions.no_struct_literal;
@@ -1149,4 +1179,18 @@ fn a(x) {
           name: rc!(Yolo), params: vec![ty!("a")]
         })]))]));
   }
+
+  #[test]
+  fn parsing_lambdas() {
+    parse_test!("{|x| x + 1}", AST(vec![
+      exprstatement!(Lambda { params: vec![(rc!(x), None)], body: vec![exprstatement!(binexp!("+", val!("x"), IntLiteral(1)))]})
+    ]));
+
+    parse_test!("{      |x: Int, y| a;b;c;}", AST(vec![
+      exprstatement!(Lambda {
+        params: vec![(rc!(x), Some(ty!("Int"))), (rc!(y), None)],
+        body: vec![exprstatement!(val!("a")), exprstatement!(val!("b")), exprstatement!(val!("c"))]
+      })
+    ]));
+  }
 }