# DocTest

### From HaskellWiki

## Contents |

## 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 source code comment with examples from an interactive Haskell session. 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)

*expression*.

All comment lines following an expression denote the
*result* of that expression. Result is defined by what an REPL

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!