cutsea110
自己解決しました。
https://wiki.haskell.org/GHC/Type_families
この What is the problem? にある
でした。
そうか、GHC will infer the type, But You can't that type.
確かに very confusing だった。 :bomb:
https://wiki.haskell.org/GHC/Type_families
この What is the problem? にある
GHC will happily infer the type g :: F a -> F a. But you can't write that type signature or, indeed, the more specific one above. (Arguably this behaviour, where GHC infers a type it can't check, is very confusing. I suppose we could make GHC reject both programs, with and without type signatures.)
でした。
そうか、GHC will infer the type, But You can't that type.
確かに very confusing だった。 :bomb: