From a720b9ffd8c347c7bda56eb752c62b1588e9b614 Mon Sep 17 00:00:00 2001
From: sebastianselander <sebastian.selander@gmail.com>
Date: Fri, 5 May 2023 15:09:51 +0200
Subject: [PATCH] Peano

---
 src/Codegen/Emits.hs |  5 +++--
 src/Main.hs          |  4 ++++
 test_program.crf     | 37 ++++++++++++++++++++++++++-----------
 3 files changed, 33 insertions(+), 13 deletions(-)

diff --git a/src/Codegen/Emits.hs b/src/Codegen/Emits.hs
index 5ab9801..bc19f87 100644
--- a/src/Codegen/Emits.hs
+++ b/src/Codegen/Emits.hs
@@ -325,6 +325,7 @@ emitApp rt e1 e2 = appEmitter e1 e2 []
                 let call =
                         case name of
                             TIR.Ident ('l' : 't' : '$' : _) -> Icmp LLSlt I64 (snd (head args')) (snd (args' !! 1))
+                            TIR.Ident ('$' : 'm' : 'i' : 'n' : 'u' : 's' : '$' : '$' : _) -> Sub I64 (snd (head args')) (snd (args' !! 1))
                             _ -> Call FastCC (type2LlvmType rt) visibility name args'
                 emit $ Comment $ show rt
                 emit $ SetVariable vs call
@@ -359,8 +360,8 @@ exprToValue = \case
     (MIR.ELit i, _t) -> pure $ case i of
         (MIR.LInt i) -> VInteger i
         (MIR.LChar i) -> VChar $ ord i
-    (MIR.EVar (TIR.Ident "True"), _t) -> pure $ VInteger 1
-    (MIR.EVar (TIR.Ident "False"), _t) -> pure $ VInteger 0
+    (MIR.EVar (TIR.Ident "True$Bool"), _t) -> pure $ VInteger 1
+    (MIR.EVar (TIR.Ident "False$Bool"), _t) -> pure $ VInteger 0
     (MIR.EVar name, t) -> do
         funcs <- gets functions
         cons <- gets constructors
diff --git a/src/Main.hs b/src/Main.hs
index b70a80c..ea6103a 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -187,4 +187,8 @@ prelude =
         , "    _ => True"
         , "    _ => False"
         , "\n"
+        , -- The function body of - is replaced during code gen. It exists here for type checking purposes.
+          ".- : Int -> Int -> Int"
+        , ".- x y = 0"
+        , "\n"
         ]
diff --git a/test_program.crf b/test_program.crf
index 5f35a1d..6e528dc 100644
--- a/test_program.crf
+++ b/test_program.crf
@@ -1,15 +1,30 @@
-data List a where
-    Cons : a -> List a -> List a
-    Nil : List a
+-- Peano naturals
+data Nat where
+  Zero : Nat
+  Succ : Nat -> Nat
 
-.++ xs ys = case xs of
-    Nil => ys
-    Cons z zs => Cons z (zs ++ ys)
+toInt : Nat -> Int
+toInt a = case a of
+    Succ n => 1 + toInt n
+    Zero => 0
 
-length xs = case xs of
-    Cons x xs => 1 + length xs
+fromInt a = case a of
+    0 => Zero
+    n => Succ (fromInt (a - 1))
 
-main = length (list1 ++ list2)
+-- Peano arithmetic --
 
-list1 = Cons 0 (Cons 1 (Cons 2 (Cons 3 Nil)))
-list2 = Cons 4 (Cons 5 (Cons 6 (Cons 7 Nil)))
+-- Peano addition
+add : Nat -> Nat -> Nat
+add left right = case left of
+    Zero => right
+    Succ n => Succ (add n right)
+
+-- Peano multiplication
+mul : Nat -> Nat -> Nat
+mul left right = case right of
+    Zero => Zero
+    Succ n => add left (mul left n)
+
+-- Returns 10_000
+main = toInt (mul (fromInt 100) (fromInt 100))