From 34b86f22fddce09c6d45d4ba743cc9d1f4eceff9 Mon Sep 17 00:00:00 2001
From: Rose Hogenson <rosehogenson@posteo.net>
Date: Sat, 4 May 2024 15:54:23 -0700
Subject: Add "fun" syntax.

---
 parser.sml       | 28 +++++++++++++++++++---------
 tests/14-fun.sml |  3 +++
 2 files changed, 22 insertions(+), 9 deletions(-)
 create mode 100644 tests/14-fun.sml

diff --git a/parser.sml b/parser.sml
index e4c7359..c1432f2 100644
--- a/parser.sml
+++ b/parser.sml
@@ -458,15 +458,25 @@ struct
       const (Syntax.ECase (e, arms)))))
   <|> orelseExpr) st
   and dec : Syntax.dec parser = fn st =>
-    (reserved "val" >>
-    bind (true <$ reserved "rec" <|> const false) (fn isRec =>
-    bind pat (fn p =>
-    reserved "=" >>
-    bind expr (fn e =>
-    const
-      (if isRec
-      then Syntax.DValRec (p, e)
-      else Syntax.DVal (p, e)))))) st
+      ((reserved "val" >>
+      bind (true <$ reserved "rec" <|> const false) (fn isRec =>
+      bind pat (fn p =>
+      reserved "=" >>
+      bind expr (fn e =>
+      const
+        (if isRec
+        then Syntax.DValRec (p, e)
+        else Syntax.DVal (p, e))))))
+  <|> (reserved "fun" >>
+      bind identifier (fn name =>
+      bind (many1 atpat) (fn args =>
+      reserved "=" >>
+      bind expr (fn body =>
+      const
+        (Syntax.DValRec
+          ( Syntax.PVar name
+          , foldr Syntax.ELambda body args
+          ))))))) st
 
   val program : Syntax.expr parser = (fn decs => Syntax.ELet (decs, Syntax.EInt 0)) <$> many dec
   fun parse (f : string) : (string, Syntax.expr) Result.either = runParser program f
diff --git a/tests/14-fun.sml b/tests/14-fun.sml
new file mode 100644
index 0000000..210b30d
--- /dev/null
+++ b/tests/14-fun.sml
@@ -0,0 +1,3 @@
+fun f x y = __builtin "exit" (__builtin "sub" (x, y))
+
+val _ = f 60 18
-- 
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