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https://github.com/julow/nix-opam-switch
Create Opam switches where the compiler and tools are built by Nix.
https://github.com/julow/nix-opam-switch
Last synced: 2 months ago
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Create Opam switches where the compiler and tools are built by Nix.
- Host: GitHub
- URL: https://github.com/julow/nix-opam-switch
- Owner: Julow
- Created: 2023-06-30T16:34:02.000Z (over 1 year ago)
- Default Branch: main
- Last Pushed: 2024-07-12T13:02:23.000Z (6 months ago)
- Last Synced: 2024-10-13T21:42:01.483Z (3 months ago)
- Language: Nix
- Size: 24.4 KB
- Stars: 10
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# nix-opam-switch
Create and maintain Opam switches where the compiler and tools are built by Nix.
This brings several advantages:
- Several switches can share the same compiler and tools.
Reduces disk usage and makes switch creation potentially instant.
- The compiler and the tools might be fetched from Nix's online cache.
If the compiler have not been built before, there's a chance that it could be
fetched in seconds.
- Tools' dependencies are not installed in the switch.
They cannot interfere with the projects' dependencies.
- Switches created by this tool do not expire on NixOS.
The compiler and other binaries contain absolute paths to C libraries that
are not recorded as GC roots and are eventually collected.
The tools installed alongside the compiler are:
- Merlin
- ocp-indent
- OCamlformat (with version specified in `./.ocamlformat`)
## Install
This tool relies on Nix and Opam to be also installed, they are not part of the
closure to avoid messing up with their mutable states.
Save this to a file and run `nix-env -if the_file.nix`:
```nix
{ pkgs ? import { } }:
# Or use the following in your NixOS configuration, nixpkgs overlay, etc..
pkgs.callPackage (pkgs.fetchgit {
url = "https://github.com/Julow/nix-opam-switch";
rev = "d9035b22b3e362210e190bab36f58fd18743992e";
sha256 = "sha256-svGlLtYysrgNA3/E1kWsgDvGU51lAXdH8z7qIn/2tD0=";
}) { }
```
Or installation from source (useful to hack on the code):
```bash
git clone https://github.com/Julow/nix-opam-switch
cd nix-opam-switch
nix-env -if .
```
`nix-env` can be repeated to update the package.
## Usage
### Local switch
To create a local switch with a recent version of OCaml, Merlin, ocp-indent and OCamlformat installed:
```bash
$ nix-opam-switch create .
```
To create a local switch with a specific version of OCaml:
```bash
$ nix-opam-switch list-available
...
4.14
5.0
$ nix-opam-switch create . 5.0
```
## Global switch
To create a global switch:
```bash
$ nix-opam-switch create 4.14
$ nix-opam-switch create 4.14-foo 4.14
$ nix-opam-switch create 4.14-foo # Shortcut for the previous command
```
### Re-installing OCamlformat
To install the version of OCamlformat specified by the `.ocamlformat` in the
current directory:
```bash
$ nix-opam-switch ocamlformat
```
To install a specified version of OCamlformat:
```bash
$ nix-opam-switch ocamlformat 0.24.1
```