How to create more readable multi-line strings in Haskell?

Question

I am new to Haskell, and am working on testing JSON serialization. Here is what the test case looks like:

{-# LANGUAGE OverloadedStrings #-}

module WetlandsTest where

import Control.Exception (evaluate)
import Test.Hspec
import Wetlands

main :: IO ()
main = hspec $ do
  describe "wetlands" $ do
    describe "spotting" $ do
      it "returns a json encoded spotting" $ do
        let record = spotting "Snowy Egret" "California" "low tide"
        record `shouldBe` "{\"bird\":\"Snowy Eget\",\"state\":\"California\",\"meta\":\"low tide\"}"

Is there a way to write that in a more readable way? Maybe something along the lines of:

record `shouldBe` """
{"bird":"Snowy Eget","city":"California","meta":"low tide"}
"""

This isn't necessarily a multiline string, but if you prettified the JSON then it would be. Just wondering in general.

This is unrelated to the specific question but all of those dos are unnecessary as it stands, so you could clean it up some by eliminating those as well. — David Young
– David Young, Commented Nov 2, 2014 at 22:47

zbee · Accepted Answer · 2019-10-09 07:33:20Z

14

Just use the quasi-quotes extension and the string-qq package:

{-# LANGUAGE QuasiQuotes #-}
import Data.String.QQ

someString :: String
someString = [s|
This is"
some string with "" quotes and stuff"!
|]

With output:

*Main> someString 
"This is\"\nsome string with \"\" quotes and stuff\"!\n"

edited Oct 9, 2019 at 7:33

zbee

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answered Nov 2, 2014 at 22:43

Thomas M. DuBuisson

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