From 762a6aef9b3cfb19ea4f693aaa057fde92b6f619 Mon Sep 17 00:00:00 2001
From: sebastianselander <sebastian.selander@gmail.com>
Date: Mon, 8 May 2023 17:48:29 +0200
Subject: [PATCH] Fixed codegen bug, added prelude option, created lambda calc

---
 sample-programs/lambda_calculus.crf | 63 +++++++++++++++++++++++++++++
 src/Codegen/Emits.hs                |  2 +-
 src/Main.hs                         | 12 ++++++
 3 files changed, 76 insertions(+), 1 deletion(-)
 create mode 100644 sample-programs/lambda_calculus.crf

diff --git a/sample-programs/lambda_calculus.crf b/sample-programs/lambda_calculus.crf
new file mode 100644
index 0000000..cccbf2f
--- /dev/null
+++ b/sample-programs/lambda_calculus.crf
@@ -0,0 +1,63 @@
+data Exp where
+    -- Integer for the variable name to be able to use (==)
+    -- as we do not have type classes.
+    EVar : Int -> Exp
+    EInt : Int -> Exp
+    EAbs : Int -> Exp -> Exp
+    EApp : Exp -> Exp -> Exp
+    EAdd : Exp -> Exp -> Exp
+
+data Pair a b where
+    Pair : a -> b -> Pair a b
+
+data Env where
+    Env : List (Pair Int Val) -> Env
+
+data Val where
+    VInt : Int -> Val
+    VClos : Env -> Int -> Exp -> Val
+
+data List a where
+    Nil : List a
+    Cons : a -> List a -> List a
+
+-- interp : Env -> Exp -> Val
+interp env exp = case exp of
+    EInt i => VInt i
+    EAdd e1 e2 => case interp env e1 of
+        VInt i => case interp env e2 of
+            VInt j => VInt (i + j)
+    EAbs ident expr => VClos env ident expr
+    EApp e1 e2 => case interp env e1 of
+        VClos closEnv ident exp => case interp env e2 of
+            v => interp (insert ident v closEnv) exp
+            -- Crash of incorrect program
+    EVar v => lookupVar v env
+
+-- lookupVar : Int -> Env -> Val
+lookupVar ident env = case env of
+    Env list => case list of
+        Cons a as => case a of
+            Pair identy val => case ident == identy of
+                True => val
+                False => lookupVar ident (Env as)
+        -- If the variable does not exist in
+        -- the context then we just crash the program
+
+-- insert : Int -> Val -> Env -> Env
+insert ident v env = case env of
+    Env list => Env (Cons (Pair ident v) list)
+
+-- eval : Val -> Int
+eval v = case v of
+    VInt i => i
+    -- Fail unless the final value is an integer
+
+-- expression : Exp
+expression = EApp (EAbs 0 (EAdd (EVar 0) (EInt 20))) (EInt 123)
+
+-- context : Env
+context = Env Nil
+
+-- main : Int
+main = eval (interp context expression)
diff --git a/src/Codegen/Emits.hs b/src/Codegen/Emits.hs
index fb9ed35..1545a6c 100644
--- a/src/Codegen/Emits.hs
+++ b/src/Codegen/Emits.hs
@@ -320,7 +320,7 @@ emitECased t e cases = do
         emit $ Label lbl_failPos
     emitCases rt ty label stackPtr vs (Branch (PEnum (Ident "True$Bool"), t) exp) = do
         emitCases rt ty label stackPtr vs (Branch (PLit $ LInt 1, t) exp)
-    emitCases rt ty label stackPtr vs (Branch (PEnum (Ident "False$Bool"), _) exp) = do
+    emitCases rt ty label stackPtr vs (Branch (PEnum (Ident "False$Bool"), t) exp) = do
         emitCases rt ty label stackPtr vs (Branch (PLit (LInt 0), t) exp)
     emitCases rt ty label stackPtr vs br@(Branch (PEnum consId, _) exp) = do
         emit $ Comment "Penum"
diff --git a/src/Main.hs b/src/Main.hs
index 4dcf1a5..9862d8e 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -58,6 +58,7 @@ flags =
     [ Option ['d'] ["debug"] (NoArg enableDebug) "Print debug messages."
     , Option ['t'] ["type-checker"] (ReqArg chooseTypechecker "bi/hm") "Choose type checker. Possible options are bi and hm"
     , Option ['m'] ["disable-gc"] (NoArg disableGC) "Disables the garbage collector and uses malloc instead."
+    , Option ['p'] ["disable-prelude"] (NoArg disablePrelude) "Do not include the prelude"
     , Option [] ["help"] (NoArg enableHelp) "Print this help message"
     ]
 
@@ -68,6 +69,7 @@ initOpts =
         , debug = False
         , gc = True
         , typechecker = Nothing
+        , preludeOpt = True
         }
 
 enableHelp :: Options -> Options
@@ -79,6 +81,9 @@ enableDebug opts = opts{debug = True}
 disableGC :: Options -> Options
 disableGC opts = opts{gc = False}
 
+disablePrelude :: Options -> Options
+disablePrelude opts = opts{preludeOpt = False}
+
 chooseTypechecker :: String -> Options -> Options
 chooseTypechecker s options = options{typechecker = tc}
   where
@@ -92,6 +97,7 @@ data Options = Options
     , debug       :: Bool
     , gc          :: Bool
     , typechecker :: Maybe TypeChecker
+    , preludeOpt     :: Bool
     }
 
 main' :: Options -> String -> IO ()
@@ -184,4 +190,10 @@ prelude =
           ".- : Int -> Int -> Int"
         , ".- x y = 0"
         , "\n"
+        , ".== : Int -> Int -> Bool"
+        , ".== a b = case a < b of"
+        , "    False => case b < a of"
+        , "        False => True"
+        , "        _ => False"
+        , "    False => False"
         ]