From 70468c0217e70858bfa037ad81ce8caf1b582ec2 Mon Sep 17 00:00:00 2001
From: Jan Tuomi <jan.tuomi@valuemotive.com>
Date: Sat, 24 Sep 2022 15:59:16 +0300
Subject: Implement let

---
 src/Builtins.hs | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

(limited to 'src/Builtins.hs')

diff --git a/src/Builtins.hs b/src/Builtins.hs
index 71401d8..1c1dd1b 100644
--- a/src/Builtins.hs
+++ b/src/Builtins.hs
@@ -9,7 +9,8 @@ builtinEnv = M.fromList [
     ("+", builtinAdd2),
     ("-", builtinSubtract2),
     ("head", builtinHead),
-    ("tail", builtinTail)
+    ("tail", builtinTail),
+    ("prepend", builtinPrepend)
     ]
 
 builtinAdd2 :: AST
@@ -46,4 +47,13 @@ builtinTail =
             (ASTVector vec) <- assertIsASTVector ast
             when (length vec == 0) $ throwError $ LException $ "tail of empty vector"
             return $ ASTVector $ tail vec
+     in ASTFunction outer
+
+builtinPrepend :: AST
+builtinPrepend =
+    let outer ast1 = do
+            let inner ast2 = do
+                    (ASTVector vec) <- assertIsASTVector ast2
+                    return $ ASTVector $ ast1 : vec
+            return $ ASTFunction $ inner
      in ASTFunction outer
\ No newline at end of file
-- 
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