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Revision as of 08:12, 16 October 2010


1 What is DocTest

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

2 Installation

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

$ cabal install doctest

3 Usage

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

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/

4 Hacking

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

Patches are gladly welcome!