39 lines
1.4 KiB
Haskell
39 lines
1.4 KiB
Haskell
{-# LANGUAGE QuasiQuotes, OverloadedStrings #-}
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module Core.HindleyMilnerSpec
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( spec
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)
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where
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----------------------------------------------------------------------------------
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import Core.Syntax
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import Core.TH (coreExpr)
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import Core.HindleyMilner (infer, TypeError(..), HMError)
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import Test.Hspec
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----------------------------------------------------------------------------------
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-- TODO: more tests. preferrably property-based. lol.
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spec :: Spec
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spec = do
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it "should infer `id 3` :: Int" $
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let g = [ ("id", "a" :-> "a") ]
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in infer g [coreExpr|id 3|] `shouldBe` Right TyInt
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it "should not infer `id 3` when `id` is specialised to `a -> a`" $
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let g = [ ("id", ("a" :-> "a") :-> "a" :-> "a") ]
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in infer g [coreExpr|id 3|] `shouldSatisfy` isUntypedVariableErr
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-- TODO: property-based tests for let
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it "should infer `let x = 3 in id x` :: Int" $
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let g = [ ("id", "a" :-> "a") ]
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e = [coreExpr|let {x = 3} in id x|]
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in infer g e `shouldBe` Right TyInt
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it "should infer `let x = 3; y = 2 in (+#) x y` :: Int" $
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let g = [ ("+#", TyInt :-> TyInt :-> TyInt) ]
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e = [coreExpr|let {x=3;y=2} in (+#) x y|]
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in infer g e `shouldBe` Right TyInt
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isUntypedVariableErr :: HMError a -> Bool
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isUntypedVariableErr (Left (TyErrCouldNotUnify _ _)) = True
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isUntypedVariableErr _ = False
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