Answer by semicolon for GADT's failed exhaustiveness checking
As already mentioned. The case you are not handling is Inl _|_, which is not itself _|_, and thus must be handled.Luckily there is a perfectly nice way to handle this:data (:+:) f g a = Inl (f a) | Inr...
View ArticleAnswer by Ben for GADT's failed exhaustiveness checking
The problem actually reported is:Warning: Pattern match(es) are non-exhaustive In an equation for `fun': Patterns not matched: Inl _Which is true. You provide a case for the Inr constructor, but not...
View ArticleAnswer by C. A. McCann for GADT's failed exhaustiveness checking
I'm sorry to tell you this, but your first example is not quite as exhaustive as you think it is:∀x. x ⊢ fun (Inl (undefined :: Foo B))*** Exception: Test.hs:48:1-17: Non-exhaustive patterns in...
View ArticleGADT's failed exhaustiveness checking
Consider the following code:data (:+:) f g a = Inl (f a) | Inr (g a)data Adata Bdata Foo l where Foo :: Foo Adata Bar l where Bar :: Bar Btype Sig = Foo :+: Barfun :: Sig B -> Intfun (Inr Bar) =...
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