Haskell / GHC - 是否有任何中缀标签/杂注用于“警告不完整模式” [英] Haskell / GHC -- is there any infix tag / pragma for "warn incomplete patterns"

问题描述

我正在寻找一个会在特定的不完整模式中发出警告的编译指示。它会使编译器失败，出现以下（假设）代码：

I'm looking for a pragma that will warn on a particular incomplete pattern. It would make the compiler fail with the following (hypothetical) code:

{-# FAILIF incomplete-patterns #-}
f :: Int -> Int
f 0 = 0

我试图用箭头编写一个编译器，知道模式匹配完成将有助于隔离错误。感谢！

I am trying to write a "compiler" using Arrows, and knowing pattern matching is complete would help isolate bugs. Thanks!

推荐答案

您可以使用 -Wall



You can require warnings, including incomplete patterns, with -Wall:

{-# OPTIONS_GHC -Wall #-}

module A where

f :: Int -> Int
f 0 = 0

收益率：

Yielding:

A.hs:6:1:
Warning: Pattern match(es) are non-exhaustive
     In an equation for `f':
         Patterns not matched: GHC.Types.I# #x with #x `notElem` [0#]

或者更具体地说， -fwarn-incomplete-patterns 取代 -Wall 。

Or more specifically, with -fwarn-incomplete-patterns inplace of -Wall.

没有什么东西可以在每个表达式的基础上工作：目前您仅限于每个模块。

There's nothing that will work on a per-expression basis: you're currently restricted to a per-module basis.

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