From 4e8641a41505f2b80348a85f6395cb7f3b996d3e Mon Sep 17 00:00:00 2001 From: Alexander Ben Nasrallah Date: Mon, 1 Mar 2021 15:11:59 +0100 Subject: agda: extend agda language frameworks manual section - add code snippets - be more detailed on some aspects --- doc/languages-frameworks/agda.section.md | 99 +++++++++++++++++++++++++++++--- 1 file changed, 90 insertions(+), 9 deletions(-) (limited to 'doc') diff --git a/doc/languages-frameworks/agda.section.md b/doc/languages-frameworks/agda.section.md index 30a266502bf34..1675fcb0a79ca 100644 --- a/doc/languages-frameworks/agda.section.md +++ b/doc/languages-frameworks/agda.section.md @@ -2,16 +2,19 @@ ## How to use Agda -Agda can be installed from `agda`: -```ShellSession -$ nix-env -iA agda -``` +Agda is available as the [agda](https://search.nixos.org/packages?channel=unstable&show=agda&from=0&size=30&sort=relevance&query=agda) +package. -To use Agda with libraries, the `agda.withPackages` function can be used. This function either takes: +The `agda` package installs an Agda-wrapper, which calls `agda` with `--library-file` +set to a generated library-file within the nix store, this means your library-file in +`$HOME/.agda/libraries` will be ignored. By default the agda package installs Agda +with no libraries, i.e. the generated library-file is empty. To use Agda with libraries, +the `agda.withPackages` function can be used. This function either takes: * A list of packages, * or a function which returns a list of packages when given the `agdaPackages` attribute set, * or an attribute set containing a list of packages and a GHC derivation for compilation (see below). +* or an attribute set containing a function which returns a list of packages when given the `agdaPackages` attribute set and a GHC derivation for compilation (see below). For example, suppose we wanted a version of Agda which has access to the standard library. This can be obtained with the expressions: @@ -27,9 +30,66 @@ agda.withPackages (p: [ p.standard-library ]) or can be called as in the [Compiling Agda](#compiling-agda) section. -If you want to use a library in your home directory (for instance if it is a development version) then typecheck it manually (using `agda.withPackages` if necessary) and then override the `src` attribute of the package to point to your local repository. +If you want to use a different version of a library (for instance a development version) +override the `src` attribute of the package to point to your local repository + +```nix +agda.withPackages (p: [ + (p.standard-library.overrideAttrs (oldAttrs: { + version = "local version"; + src = /path/to/local/repo/agda-stdlib; + })) +]) +``` + +You can also reference a GitHub repository +```nix +agda.withPackages (p: [ + (p.standard-library.overrideAttrs (oldAttrs: { + version = "1.5"; + src = fetchFromGitHub { + repo = "agda-stdlib"; + owner = "agda"; + rev = "v1.5"; + sha256 = "16fcb7ssj6kj687a042afaa2gq48rc8abihpm14k684ncihb2k4w"; + }; + })) +]) +``` + +If you want to use a library not added to Nixpkgs, you can add a +dependency to a local library by calling `agdaPackages.mkDerivation`. +```nix +agda.withPackages (p: [ + (p.mkDerivation { + pname = "your-agda-lib"; + version = "1.0.0"; + src = /path/to/your-agda-lib; + }) +]) +``` + +Again you can reference GitHub -Agda will not by default use these libraries. To tell Agda to use the library we have some options: +```nix +agda.withPackages (p: [ + (p.mkDerivation { + pname = "your-agda-lib"; + version = "1.0.0"; + src = fetchFromGitHub { + repo = "repo"; + owner = "owner"; + version = "..."; + rev = "..."; + sha256 = "..."; + }; + }) +]) +``` + +See [Building Agda Packages](#building-agda-packages) for more information on `mkDerivation`. + +Agda will not by default use these libraries. To tell Agda to use a library we have some options: * Call `agda` with the library flag: ```ShellSession @@ -46,7 +106,7 @@ depend: standard-library More information can be found in the [official Agda documentation on library management](https://agda.readthedocs.io/en/v2.6.1/tools/package-system.html). ## Compiling Agda -Agda modules can be compiled with the `--compile` flag. A version of `ghc` with `ieee754` is made available to the Agda program via the `--with-compiler` flag. +Agda modules can be compiled using the GHC backend with the `--compile` flag. A version of `ghc` with `ieee754` is made available to the Agda program via the `--with-compiler` flag. This can be overridden by a different version of `ghc` as follows: ```nix @@ -65,6 +125,21 @@ A derivation can then be written using `agdaPackages.mkDerivation`. This has sim * `libraryName` should be the name that appears in the `*.agda-lib` file, defaulting to `pname`. * `libraryFile` should be the file name of the `*.agda-lib` file, defaulting to `${libraryName}.agda-lib`. +Here is an example `default.nix` + +```nix +{ nixpkgs ? }: +with (import nixpkgs {}); +agdaPackages.mkDerivation { + version = "1.0"; + pname = "my-agda-lib"; + src = ./.; + buildInputs = [ + agdaPackages.standard-library + ]; +} +``` + ### Building Agda packages The default build phase for `agdaPackages.mkDerivation` simply runs `agda` on the `Everything.agda` file. If something else is needed to build the package (e.g. `make`) then the `buildPhase` should be overridden. @@ -80,10 +155,16 @@ By default, Agda sources are files ending on `.agda`, or literate Agda files end ## Adding Agda packages to Nixpkgs To add an Agda package to `nixpkgs`, the derivation should be written to `pkgs/development/libraries/agda/${library-name}/` and an entry should be added to `pkgs/top-level/agda-packages.nix`. Here it is called in a scope with access to all other Agda libraries, so the top line of the `default.nix` can look like: + ```nix { mkDerivation, standard-library, fetchFromGitHub }: ``` -and `mkDerivation` should be called instead of `agdaPackages.mkDerivation`. Here is an example skeleton derivation for iowa-stdlib: + +Note that the derivation function is called with `mkDerivation` set to `agdaPackages.mkDerivation`, therefore you +could use a similar set as in your `default.nix` from [Writing Agda Packages](#writing-agda-packages) with +`agdaPackages.mkDerivation` replaced with `mkDerivation`. + +Here is an example skeleton derivation for iowa-stdlib: ```nix mkDerivation { -- cgit 1.4.1