{"id":1358,"date":"2021-04-02T19:11:48","date_gmt":"2021-04-03T02:11:48","guid":{"rendered":"https:\/\/coderpad-staging.io\/?post_type=programming-language&p=1088"},"modified":"2025-12-04T03:53:46","modified_gmt":"2025-12-04T11:53:46","slug":"haskell","status":"publish","type":"programming-language","link":"https:\/\/coderpad.io\/languages\/haskell\/","title":{"rendered":"Haskell"},"content":{"rendered":"\n

Your code is run with runghc solution.hs<\/code>. Your code runs in interpreted mode, so you don\u2019t need a special entrypoint.<\/p>\n\n\n\n

We have a couple testing options available. Simple tests using Hspec<\/a> are straightforward:<\/p>\n\n\n

import<\/span> Test.Hspec\nimport<\/span> Test.QuickCheck\nimport<\/span> Control.Exception (evaluate<\/span>)\n\nmain<\/span> :: IO<\/span> ()\nmain<\/span> = hspec $ do<\/span>\n  describe \"Prelude.head\"<\/span> $ do<\/span>\n    it \"returns the first element of a list\"<\/span> $ do<\/span>\n      head [23<\/span> ..] `shouldBe` (23<\/span> :: Int<\/span>)\n\n    it \"returns the first element of an *arbitrary* list\"<\/span> $\n      property $ \\x xs -> head (x:xs) == (x :: Int<\/span>)\n\n    it \"throws an exception if used with an empty list\"<\/span> $ do<\/span>\n      evaluate (head []) `shouldThrow` anyException\n<\/code><\/span>Code language:<\/span> Haskell<\/span> (<\/span>haskell<\/span>)<\/span><\/small><\/pre>\n\n\n
import<\/span> Test.QuickCheck\n\nprop_revapp<\/span> :: [Int<\/span>] -> [Int<\/span>] -> Bool<\/span>\nprop_revapp<\/span> xs ys = reverse (xs++ys) == reverse xs ++ reverse ys\n\nmain<\/span> = quickCheck prop_revapp\n<\/code><\/span>Code language:<\/span> Haskell<\/span> (<\/span>haskell<\/span>)<\/span><\/small><\/pre>\n\n\n
We install a variety of packages in the Haskell environment (including req<\/code> for HTTP requests). The output of cabal list --installed --simple<\/code> is below:<\/p>\n\n\n\n
Package<\/th>Version<\/th><\/tr><\/thead>
HUnit<\/td>1.6.2.0<\/td><\/tr>
QuickCheck<\/td>2.14.2<\/td><\/tr>
SHA<\/td>1.6.4.4<\/td><\/tr>
bytestring<\/td>0.11.3.1<\/td><\/tr>
hashtables<\/td>1.3.1<\/td><\/tr>
hspec<\/td>2.10.8<\/td><\/tr>
network<\/td>3.1.2.7<\/td><\/tr>
parsec<\/td>3.1.15.1<\/td><\/tr>
req<\/td>3.13.0<\/td><\/tr>
split<\/td>0.2.3.5<\/td><\/tr>
text<\/td>2.0.1<\/td><\/tr>
unordered-containers<\/td>0.2.19.1<\/td><\/tr>
vector<\/td>0.13.0.0<\/td><\/tr>
vector-algorithms<\/td>0.9.0.1<\/td><\/tr><\/tbody><\/table><\/figure>\n","protected":false},"parent":0,"menu_order":0,"template":"","class_list":["post-1358","programming-language","type-programming-language","status-publish","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/coderpad.io\/wp-json\/wp\/v2\/programming-language\/1358","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/coderpad.io\/wp-json\/wp\/v2\/programming-language"}],"about":[{"href":"https:\/\/coderpad.io\/wp-json\/wp\/v2\/types\/programming-language"}],"wp:attachment":[{"href":"https:\/\/coderpad.io\/wp-json\/wp\/v2\/media?parent=1358"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
You can also use QuickCheck\u2019s<\/a> more powerful test generation framework directly (this test fails):<\/p>\n\n\n