Idris：是否可以使用“ with”重写所有函数以使用“ case”而不是“ with”？如果没有，您能举个反例吗？

不可能。当您使用模式匹配时with，将使用从匹配的构造函数中提取的信息来更新上下文中的类型。case不会引起这种更新。

例如，以下适用于with但不适用于case：

import Data.So

-- here (n == 10) in the goal type is rewritten to True or False
-- after the match
maybeTen : (n : Nat) -> Maybe (So (n == 10))
maybeTen n with (n == 10)
  maybeTen n | False = Nothing
  maybeTen n | True  = Just Oh

-- Here the context knows nothing about the result of (n == 10)
-- after the "case" match, so we can't fill in the rhs
maybeTen' : (n : Nat) -> Maybe (So (n == 10))
maybeTen' n = case (n == 10) of
  True  => ?a 
  False => ?b