当前行为
Prelude> show _
<interactive>:7:6:
Found hole ‘_’ with type: a0
Where: ‘a0’ is an ambiguous type variable
Relevant bindings include it :: String (bound at <interactive>:7:1)
In the first argument of ‘show’, namely ‘_’
In the expression: show _
In an equation for ‘it’: it = show _
期望的行为
如果GHC还能告诉我类型化的洞有Show
类型的类约束,那就太好了。
其他
GHC版本7.8.1
https://stackoverflow.com/questions/23028124
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