For writing articles on Haskell, rather than showing ghci input/output like:

Prelude> map (*2) [1..10]
[2,4,6,8,10,12,14,16,18,20]

I do the following:

setup

import Test.HUnit
import Test.HUnit.Util  -- https://github.com/haroldcarr/test-hunit-util

article main body

…

t1 = t "t1"
     (map (*2) [1..10])           -- "input"
     [2,4,6,8,10,12,14,16,18,20]  -- "output"

… or, if many examples evaluate to same value:

t2 = tt "t2"
     [(map (*2)          [1..10]) -- "input1"
     ,(map (\x -> x * 2) [1..10]) -- "input2"
     ]
     [2,4,6,8,10,12,14,16,18,20]  -- "output"

example accuracy

Then, in this section at the end of the article, I show the test setup:

main = do
    runTestTT $ TestList $ t1 ++ t2

and its evaluation:

main
=> Counts {cases = 3, tried = 3, errors = 0, failures = 0}

input/output format

Also note, that when I do actually show ghci input/output, rather than do:

*Main> :t t1
t1 :: [Test]

I do:

:t t1
=> t1 :: [Test]

code

The code for t, tt and a couple of other short aliases is at

• https://github.com/haroldcarr/test-hunit-util