Script interpreter

This page has mostly been superseded by the stack guide. We may remove this content in the future, but it is kept for now.

You can use stack as a script interpreter. Here is an example that uses the turtle package:

#!/usr/bin/env stack
-- stack --resolver lts-2.9 --install-ghc runghc --package turtle
{-# LANGUAGE OverloadedStrings #-}
import Turtle
main = echo "Hello World!"

Set the executable bit on the script, and then you can run it as a regular command (on Windows, you will have to run stack <script>.hs).

The first line is the usual "shebang" to use stack as a script interpreter. The second line, which is required, provides additional options to stack (due to the common limitation of the "shebang" line only being allowed a single argument). In this case, the options tell stack to use the lts-2.9 resolver, automatically install GHC if it is not already installed, and ensure the turtle package is available.