haskell - 查找局部函数的推断类型

Question

ghci(或 ghc)有没有办法找到推断的局部函数类型是什么？

例如。如果我有一个功能

f l = map f' l
   where f' = (+1)

有没有 :t - 类似 ghci 的方式来查看 f' 的推断类型是？

Answer 1

确实有，感谢 hammar 的精彩回答 here .这是简短的版本:

Prelude> :l /tmp/foo.hs
[1 of 1] Compiling Main             ( /tmp/foo.hs, interpreted )
Ok, modules loaded: Main.
*Main> :break f
Breakpoint 0 activated at /tmp/foo.hs:(1,1)-(2,18)
*Main> f [1..10]
Stopped at /tmp/foo.hs:(1,1)-(2,18)
_result :: [b] = _
[/tmp/foo.hs:(1,1)-(2,18)] *Main> :step
Stopped at /tmp/foo.hs:1:7-14
_result :: [b] = _
f' :: b -> b = _
l :: [b] = _
[/tmp/foo.hs:1:7-14] *Main> :t f'
f' :: b -> b