Difference between revisions of "DocTest"

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DocTest is available from
DocTest is available from
[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/DocTest Hackage].
[http://hackage.haskell.org/cgi-bin/hackage-scripts/package/doctest Hackage].
Install it, by typing:
Install it, by typing:

Revision as of 07:55, 24 June 2011

What is DocTest

DocTest is a small program, that checks examples in Haddock comments. It is modeled after doctest for Python.


DocTest is available from Hackage. Install it, by typing:

$ cabal install doctest


Below is a small Haskell module. The module contains a Haddock comment with some examples of interaction. The examples demonstrate how the module is supposed to be used.

module Fib where

-- | Compute Fibonacci numbers
-- Examples:
-- >>> fib 10
-- 55
-- >>> fib 5
-- 5
fib :: Int -> Int
fib 0 = 0
fib 1 = 1
fib n = fib (n - 1) + fib (n - 2)

(A line starting with >>> denotes an expression. All comment lines following an expression denote the result of that expression. Result is defined by what an REPL (e.g. ghci) prints to stdout and stderr when evaluating that expression.)

With DocTest you may check whether the implementation satisfies the given examples, by typing:

$ doctest Fib.hs

You may produce Haddock documentation for that module with:

$ haddock -h Fib.hs -o doc/


DocTest is still experimental. You can find a reference to the public source repository at Hackage.

Patches are gladly welcome!