> For the complete documentation index, see [llms.txt](https://ampersandtarski.gitbook.io/the-tools-we-use-for-ampersand/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ampersandtarski.gitbook.io/the-tools-we-use-for-ampersand/building/haskell.md).

# Building an Ampersand Compiler with Stack

To build your own Ampersand compiler is something to avoid as a user. As a developer, however, you may have reasons to do this yourself. For instance to verify what happens in older versions.

The Ampersand compiler is a Haskell program built with [stack](https://haskellstack.org/). Stack is a build tool for Haskell projects such as Ampersand. We have automated the building process (using stack) for the following purposes:

1. to prevent mistakes such as dependency conflicts inside and between Haskell packages, for an uninterrupted  compilation process (robust building);
2. to generate ampersand compilers for different platforms (platform independence);
3. to provide a reproducible and reliable build process to developers with diverse development tools, operating systems, and working environments (uniform building); 
4. to allow for generating images for docker containers (containerization);
5. to accellerate the build process to increase the release frequency of Ampersand.

## Installation

[Haskell](https://www.haskell.org/) comes as part of [Stack](http://haskellstack.org), so there is no need to install Haskell separately.

The [instructions to install Stack](http://haskellstack.org) are pretty clear for the various platforms. Make sure you read the part about the STACK\_ROOT environment variable.

To compile Ampersand you need a file [package.yaml](https://github.com/AmpersandTarski/Ampersand/blob/development/package.yaml), which sits in the Ampersand repository. Fetch it and put it in you working directory. From the command-line, call command `stack install` and after a while (go get coffee!) your ampersand compiler exists! NB: If you want to build Rieks'  preprocessor as well, the magic spell is `stack install --flag ampersand:buildAll`