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What is DocTest

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


Bellow is a small Haskell module. The module contains source code comments. Those comments are examples from an interactive Haskell session and demonstrate how the module is used.

module Fib where

-- Examples:
-- > fib 10
-- 55

-- > fib 5
-- 5

fib 0 = 0
fib 1 = 1
fib n = fib (n - 1) + fib (n - 2)

With DocTest you may checks if the implementation satisfies the given examples, by typing (on your Unix shell):

$ doctest Fib.hs

Lines starting with -- > denote expressions. All comment lines following an expression denote the result of that expression. Result is defined by what a REPL (e.g. ghci) prints to stdout and stderror when evaluating that expression.

DocTest on Hackage