是否可以显示应用Haskell类型族函数的结果? [英] Is it possible to display the results of applying a Haskell type family function?

问题描述

例如，如果我有以下奇怪的类型:

For example, if I have these weird types:

{-# LANGUAGE TypeFamilies #-}
type family WeirdFamily a
type instance WeirdFamily () = Int
type instance WeirdFamily (a, b) = (a, WeirdFamily b)

我可以通过键入类似以下内容来显示(例如在GHCi中) WeirdFamily(Bool，(Char，()))的结果吗?

Can I display (e.g. in GHCi) the result of WeirdFamily (Bool, (Char, ())) by typing something like:

:t WeirdFamily (Bool, (Char, ()))

进入GHCi?

推荐答案

使用种！.

:kind! WeirdFamily (Bool, (Char, ()))
WeirdFamily (Bool, (Char, ())) :: *
= (Bool, (Char, Int))

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