From f056f76a7693534a26c352781423cbe005e95a4c Mon Sep 17 00:00:00 2001
From: pca006132 <jl@m-labs.hk>
Date: Thu, 17 Dec 2020 17:09:21 +0800
Subject: [PATCH] fixed some inference bugs

---
 toy-impl/inference.py  |  5 ++++-
 toy-impl/test_subst.py | 46 +++++++++++++++++++++++++++++-------------
 2 files changed, 36 insertions(+), 15 deletions(-)

diff --git a/toy-impl/inference.py b/toy-impl/inference.py
index 8159201..b77f3fa 100644
--- a/toy-impl/inference.py
+++ b/toy-impl/inference.py
@@ -36,7 +36,10 @@ def find_subst(ctx: dict[str, Type],
             return sub
 
     if isinstance(a, TypeVariable):
-        return f"{a} can take values other than {b}"
+        if a == b:
+            return sub
+        else:
+            return f"{a} can take values other than {b}"
 
     if isinstance(a, BotType):
         return sub
diff --git a/toy-impl/test_subst.py b/toy-impl/test_subst.py
index 451d07f..7662195 100644
--- a/toy-impl/test_subst.py
+++ b/toy-impl/test_subst.py
@@ -7,13 +7,23 @@ types = {
     'str': PrimitiveType('str'),
 }
 
+i32 = types['int32']
+i64 = types['int64']
+s = types['str']
+
 variables = {
     'X': TypeVariable('X', []),
     'Y': TypeVariable('Y', []),
-    'I': TypeVariable('I', [types['int32'], types['int64']]),
-    'A': TypeVariable('A', [types['int32'], types['int64'], types['str']]),
+    'I': TypeVariable('I', [i32, i64]),
+    'A': TypeVariable('A', [i32, i64, s]),
 }
 
+X = variables['X']
+Y = variables['Y']
+I = variables['I']
+A = variables['A']
+
+
 def stringify_subst(subst):
     if isinstance(subst, str):
         return subst
@@ -25,16 +35,24 @@ def try_case(a, b, ctx):
     print(f"{a} <- {b} w.r.t. {stringify_subst(ctx)}\n    {stringify_subst(result)}\n")
 
 
-try_case(types['int32'], types['int32'], {})
-try_case(types['int32'], types['int64'], {})
-try_case(types['int32'], variables['X'], {})
-try_case(types['int32'], variables['X'], {'X': types['int32']})
-try_case(types['int32'], variables['X'], {'X': types['int64']})
-try_case(variables['X'], variables['X'], {'X': types['int64']})
-try_case(variables['X'], variables['Y'], {'Y': types['int64']})
-try_case(variables['X'], variables['Y'], {'X': types['int64']})
-try_case(variables['I'], variables['X'], {})
-try_case(variables['I'], variables['A'], {})
-try_case(variables['A'], variables['I'], {})
-try_case(variables['X'], variables['I'], {})
+try_case(i32, i32, {})
+try_case(i32, i64, {})
+try_case(i32, X, {})
+try_case(i32, X, {'X': i32})
+try_case(i32, X, {'X': i64})
+try_case(X, X, {'X': i64})
+try_case(X, Y, {'Y': i64})
+try_case(X, Y, {'X': i64})
+try_case(I, X, {})
+try_case(I, A, {})
+try_case(A, I, {})
+try_case(X, I, {})
+try_case(ListType(i32), TupleType([i32]), {})
+try_case(TupleType([i32]), ListType(i32), {})
+try_case(ListType(i32), ListType(i32), {})
+try_case(TupleType([X, X]), TupleType([X, Y]), {})
+try_case(TupleType([X, X]), TupleType([Y, Y]), {})
+try_case(TupleType([X, Y]), TupleType([X, X]), {})
+try_case(TupleType([X, Y]), X, {})
+