Haskell：如何告诉 hlint 不要：`警告：使用字符串文字`

Question

I have a unit test file:

module X04PatMatTest where

import AssertError
import Test.HUnit
import X04PatMat

...

and hlint complains:

X04PatMatTest.hs:15:69: Warning: Use string literal 
Found:
  ['a', 'b', 'd']
Why not:
  "abd"

for various reasons, I really want to put ['a', 'b', 'd'] in the test code.

I have tried various permuatations of

{-# ANN X04PatMatTest "HLint: ignore Warning: Use string literal" #-}

like putting the pragma as the first line of the file, after the module declaration, with the name module instead of X04... , changing the Warning to warn ...

What is the magic?

Answer 1

You need to write the pragma in another way. After some trial and error I came up with the following:

module Test where

import Data.Char(toUpper)

{-# ANN module "HLint: ignore Use string literal" #-}
main :: IO ()
main = putStrLn ['a','b','c']

note that you have to write "module" and not the name of the module

Answer 2

Agree with @MoFu's solution.

hlint also support ignore specific warning with arguments.

hlint -i 'Use string literal' [filename]

add this to arguments or aliases, so ignore this warning, but not break your code.

By the way, synatastic support arguments.

Answer 3

---

With recent (>2019) hlint, you can use the simpler syntax {- HLINT ignore "some hint" -} :

module Test where

import Data.Char(toUpper)

{- HLINT ignore "Use string literal" -}
main :: IO ()
main = putStrLn ['a','b','c']

Unlike ANN , this can be placed anywhere in the file, and there's no need for annotating it as String if you use OverloadedStrings , and it will not lead to increased compile time.