# Installing

- [Installing from source](#installing-from-source)
- [Installing from a package manager](#installing-from-a-package-manager)

## Installing from source

The easiest way to install is via the existing generated Scheme code.
The requirements are:

- A Scheme compiler; either Chez Scheme (default), or Racket.
- `bash`, with `realpath`. On Linux, you probably already have this.
  On a Mac, you can install this with `brew install coreutils`.
  On FreeBSD, OpenBSD and NetBSD, you can install `realpath` and `GNU make`
  using a package manager.  For instance, on OpenBSD you can install all of them
  with `pkg_add coreutils gmake` command.

On Windows, it has been reported that installing via `MSYS2` works
(https://www.msys2.org/). On Windows older than Windows 8, you may need to
set an environment variable `OLD_WIN=1` or modify it in `config.mk`.

On Raspberry Pi, you can bootstrap via Racket.

By default, code generation is via Chez Scheme. You can use Racket instead,
by setting the environment variable `IDRIS2_CG=racket` before running `make`.
If you install Chez Scheme from source files, building it locally,
make sure you run `./configure --threads` to build multithreading support in.

**NOTE**: On FreeBSD, OpenBSD and NetBSD you need to use `gmake` command instead
of `make` in the following steps.

### 1: Set the PREFIX

- Change the `PREFIX` in `config.mk`. The default is to install in
  `$HOME/.idris2`

If you have an existing Idris 2, go to the alternative Step 2. Otherwise, read on...

Make sure that:

- `$PREFIX/bin` is in your `PATH`
- `$PREFIX/lib` is in your `LD_LIBRARY_PATH` or `DYLD_LIBRARY_PATH` if on
  `macOS` (so that the system knows where to look for library support code)

### 2: Installing without an existing Idris 2

You can build from pre-built Chez Scheme source, as long as you have Chez Scheme
installed (or, alternatively, Racket). To do this, enter one of the following:

- `make bootstrap SCHEME=chez`
- `make bootstrap-racket`

`chez` is the executable name of the Chez Scheme compiler. You may need to
replace this with the executable for Chez Scheme on your system. This could be
`scheme`, `chezscheme` or `chezscheme9.5` or something else, depending on your
system and the Chez Scheme version.

This builds an Idris 2 compiler from scheme code output from a working Idris 2
compiler (which isn't necessarily up to date, but is up to date enough to
build the current repository). It then rebuilds using the result, and runs
the tests.

If all is well, to install, type:

- `make install`

### 3: Installing with an existing Idris 2

If you have an earlier version of this Idris 2 installed

- `make all`
- `make install`

### 4: (Optional) Self-hosting step

As a final step, you can rebuild from the newly installed Idris 2 to verify
that everything has worked correctly. Assuming that `idris2` is in your
`PATH`.

- `make clean` -- to make sure you're building everything with the new version
- `make all && make install`

### 5: Running tests

After `make all`, type `make test` to check everything works. This uses the
executable in `./build/exec`.

### 6: (Optional) Installing the Idris 2 API

You'll only need this if you're developing support tools, such as an external
code generator. To do so, once everything is successfully installed, type:

- `make install-api`

The API will only work if you've completed the self-hosting step, step 3, since
the intermediate code versions need to be consistent throughout.

## Installing from a package manager

### Installing using Homebrew

If you are Homebrew user you can install Idris 2 together with all the requirements
by running the following command:

    brew install idris2

### Installing from nix

If you are a [nix](https://nixos.org/features.html) user you can install Idris 2 together with all the requirements
by running the following command:

    nix-env -i idris2