From 2b710602d3d6b6929a1df9906d2aeb52de1eab75 Mon Sep 17 00:00:00 2001
From: Dustin Swan <dustin@dustinswan.com>
Date: Fri, 27 Mar 2026 21:58:11 -0600
Subject: [PATCH] Adding more types to my stdlib functions. Cleaning up type
 checker

---
 src/cg/01-stdlib.cg | 78 ++++++++++++++++-----------------------------
 src/typechecker.ts  |  3 ++
 2 files changed, 30 insertions(+), 51 deletions(-)

diff --git a/src/cg/01-stdlib.cg b/src/cg/01-stdlib.cg
index b26e00f..8eb4358 100644
--- a/src/cg/01-stdlib.cg
+++ b/src/cg/01-stdlib.cg
@@ -60,12 +60,8 @@ entries : a \ List { key : String, value : b };
 keys : a \ List String;
 nth : Int \ a \ Maybe a;
 
-# myTest = gt 3 "hi";
-# myTest2 = cat [3, 4] [4, 5];
-# myTest3 = debug! "myTest2" myTest2;
-
 # nth : Int \ List a \ Maybe a
-# in host at the moment, until we get typeclasses or something and this can work on strings too
+# defined in host for now
 # nth = i list \ [i, list]
 #   | [_, []] \ None
 #   | [0, [x, ...xs]] \ (Some x)
@@ -75,7 +71,7 @@ map : (a \ b) \ List a \ List b = f list \ list
   | [] \ []
   | [x, ...xs] \ [f x, ...map f xs];
 
-mapWithIndex : (a \ Number \ b) \ List a \ List b = f list \
+mapWithIndex : (a \ Int \ b) \ List a \ List b = f list \
   init = { i = 0, result = [] };
   f2 = acc x \ { i = acc.i + 1, result = [...acc.result, f x acc.i] };
   (fold f2 init list).result;
@@ -105,99 +101,84 @@ insertCharAt : String \ Int \ String \ String = text pos char \
   after = slice text pos (len text);
   before & char & after;
 
-deleteCharAt = text pos \
+deleteCharAt : String \ Int \ String = text pos \
   before = slice text 0 pos;
   after = slice text (pos + 1) (len text);
   before & after;
 
-# updateAt
-updateAt = i f list \ mapWithIndex (x j \
+updateAt : Int \ (a \ a) \ List a \ List a = i f list \ mapWithIndex (x j \
   (i == j | True \ f x | False \ x)
 ) list;
 
-# fold : (b \ a \ b) \ b \ List a \ b
-fold = f acc list \ list
+fold : (b \ a \ b) \ b \ List a \ b = f acc list \ list
   | [] \ acc
   | [x, ...xs] \ fold f (f acc x) xs;
 
-# reverse : List a \ List a
-reverse = list \ list
+reverse : List a \ List a = list \ list
   | [] \ []
   | [x, ...xs] \ (reverse xs) & [x];
 
-# take : Int \ List a \ List a
-take = n list \ { n = n, list = list }
+take : Int \ List a \ List a = n list \ { n = n, list = list }
   | { n = _, list = [] } \ []
   | { n = 0, list = _ } \ []
   | { n = _, list = [x, ...xs] } \ [x, ...take (n - 1) xs];
 
-# drop : Int \ List a \ List a
-drop = n list \ { n = n, list = list }
+drop : Int \ List a \ List a = n list \ { n = n, list = list }
   | { n = _, list = [] } \ []
   | { n = 0, list = _ } \ list
   | { n = _, list = [x, ...xs] } \ drop (n - 1) xs;
 
-# join : String \ List String \ String
-join = s list \ list
+join : String \ List String \ String = s list \ list
   | [] \ ""
   | [x] \ x
   | [x, ...xs] \ (x & s & (join s xs));
 
-# repeatStr : Int \ String \ String
-repeatStr = n str \ n
+repeatStr : Int \ String \ String = n str \ n
   | 0 \ ""
   | m \ str & (repeatStr (m - 1) str);
 
-# repeat : Int \ a \ List a
-repeat = n a \ n
+repeat : Int \ a \ List a = n a \ n
   | 0 \ []
   | m \ [a, ...repeat (m - 1) a];
 
-# zipWith : (a \ b \ c) \ List a \ List b \ List c
-zipWith = f l1 l2 \ l1
+# zipWith
+zipWith : (a \ b \ c) \ List a \ List b \ List c = f l1 l2 \ l1
   | [] \ []
   | [x, ...xs] \ (l2
     | [] \ []
     | [y, ...ys] \ [f x y, ...zipWith f xs ys]);
 
-# contains : a \ List a \ Bool
-contains = x list \ list
+contains : a \ List a \ Bool = x list \ list
   | [] \ False
   | [y, ...ys] \ (x == y
     | True \ True
     | False \ contains x ys);
 
-# find : (a \ Bool) \ List a \ Maybe a
-find = f list \ list
+find : (a \ Bool) \ List a \ Maybe a = f list \ list
   | [] \ None
   | [x, ...xs] \ (f x
     | True \ Some x
     | False \ find f xs);
 
-# flatten : List (List a) \ List a
-flatten = lists \ fold cat [] lists;
+flatten : List (List a) \ List a = lists \ fold cat [] lists;
 
-# and : Bool \ Bool \ Bool
-and = x y \ x
+and : Bool \ Bool \ Bool = x y \ x
   | False \ False
   | True \ y;
 
-# or : Bool \ Bool \ Bool
-or = x y \ x
+or : Bool \ Bool \ Bool = x y \ x
   | True \ True
   | False \ y;
 
-not : bool \ bool = x \ x
+not : Bool \ Bool = x \ x
   | True \ False
   | False \ True;
 
-# isSome : Maybe a \ Bool
-isSome = a \ a
+isSome : Maybe a \ Bool = a \ a
   | Some _ \ True
   | _ \ False;
 
-# isNone : Maybe a \ Bool
-isNone = a \ a
+isNone : Maybe a \ Bool = a \ a
   | Some _ \ False
   | _ \ True;
 
@@ -205,23 +186,18 @@ unwrapOr : a \ Maybe a \ a = default x \ x
   | Some val \ val
   | _ \ default;
 
-# if : Bool \ a \ a \ a
-if = test a b \ test
+if : Bool \ a \ a \ a = test a b \ test
   | True \ a
   | _ \ b;
 
-# range : Int \ Int \ List Int
 # [start, start+1, ..., end-1]
-range = start end \ start >= end
+range : Int \ Int \ List Int = start end \ start >= end
   | True \ []
   | False \ [start, ...range (start + 1) end];
 
-# sum : List Int \ Int
-# TODO sum floats too? wait for typeclasses?
-sum = list \ fold add 0 list;
+# TODO Number
+sum : List Int \ Int = list \ fold add 0 list;
 
-# any : (a \ Bool) \ List a \ Bool
-any = f list \ fold (acc x \ or acc (f x)) False list;
+any : (a \ Bool) \ List a \ Bool = f list \ fold (acc x \ or acc (f x)) False list;
 
-# all : (a \ Bool) \ List a \ Bool
-all = f list \ fold (acc x \ and acc (f x)) True list;
+all : (a \ Bool) \ List a \ Bool = f list \ fold (acc x \ and acc (f x)) True list;
diff --git a/src/typechecker.ts b/src/typechecker.ts
index efc00d8..bddcdac 100644
--- a/src/typechecker.ts
+++ b/src/typechecker.ts
@@ -32,6 +32,9 @@ function unify(t1: TypeAST, t2: TypeAST, subst: Subst): string | null {
     // Same type name
     if (a.kind === 'type-name' && b.kind === 'type-name' && a.name === b.name) return null;
 
+    // Same type var
+    if (a.kind === 'type-var' && b.kind === 'type-var' && a.name === b.name) return null;
+
     // Type var binds to anything
     if (a.kind === 'type-var') {
         if (occursIn(a.name, b, subst)) return `Infinite type: ${a.name} occurs in ${prettyPrintType(b)}`;