在Haskell / HappStack中有关语法和类型签名的新手问题
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为什么我不能做
z = x?
y s = x s
Prelude> import Happstack.Server
Prelude Happstack.Server> let x s = ok $ toResponse $ \"Some string\"
Prelude Happstack.Server> :t x
x :: FilterMonad Response m => t -> m Response
Prelude Happstack.Server> let y s = x s
Prelude Happstack.Server> :t y
y :: FilterMonad Response m => t -> m Response
Prelude Happstack.Server> let z = x
<interactive>:1:9:
No instance for (FilterMonad Response m0)
arising from a use of `x\'
没有找到相关结果
已邀请:
1 个回复
稳赣苍卯改
，包含显式类型签名，也可以使用运行GHCi。