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diff --git a/doc/languages-frameworks/agda.section.md b/doc/languages-frameworks/agda.section.md index 9ce046d05b6..2b7c35f68d3 100644 --- a/doc/languages-frameworks/agda.section.md +++ b/doc/languages-frameworks/agda.section.md @@ -1,91 +1,178 @@ ---- -title: Agda -author: Alex Rice (alexarice) -date: 2020-01-06 ---- -# Agda +# Agda {#agda} -## How to use Agda +## How to use Agda {#how-to-use-agda} -Agda can be installed from `agda`: -``` -$ 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: -+ 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). +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 +`$HOME/.agda/libraries` will be ignored. By default the agda package installs Agda +with no libraries, i.e. the generated library-file is empty. To use Agda with libraries, +the `agda.withPackages` function can be used. This function either takes: -For example, suppose we wanted a version of agda which has access to the standard library. This can be obtained with the expressions: +* A list of packages, +* or a function which returns a list of packages when given the `agdaPackages` attribute set, +* or an attribute set containing a list of packages and a GHC derivation for compilation (see below). +* or an attribute set containing a function which returns a list of packages when given the `agdaPackages` attribute set and a GHC derivation for compilation (see below). -``` +For example, suppose we wanted a version of Agda which has access to the standard library. This can be obtained with the expressions: + +```nix agda.withPackages [ agdaPackages.standard-library ] ``` or -``` +```nix agda.withPackages (p: [ p.standard-library ]) ``` or can be called as in the [Compiling Agda](#compiling-agda) section. -If you want to use a library in your home directory (for instance if it is a development version) then typecheck it manually (using `agda.withPackages` if necessary) and then override the `src` attribute of the package to point to your local repository. - -Agda will not by default use these libraries. To tell agda to use the library we have some options: -- Call `agda` with the library flag: -``` -$ agda -l standard-library -i . MyFile.agda -``` -- Write a `my-library.agda-lib` file for the project you are working on which may look like: -``` -name: my-library -include: . -depend: standard-library -``` -- Create the file `~/.agda/defaults` and add any libraries you want to use by default. +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 + +```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 + $ agda -l standard-library -i . MyFile.agda + ``` +* Write a `my-library.agda-lib` file for the project you are working on which may look like: + ``` + name: my-library + include: . + depend: standard-library + ``` +* Create the file `~/.agda/defaults` and add any libraries you want to use by default. 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 `ieee` is made available to the Agda program via the `--with-compiler` flag. +## Compiling Agda {#compiling-agda} + +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 agda.withPackages { pkgs = [ ... ]; ghc = haskell.compiler.ghcHEAD; } ``` -## Writing Agda packages -To write a nix derivation for an agda library, first check that the library has a `*.agda-lib` file. +## Writing Agda packages {#writing-agda-packages} + +To write a nix derivation for an Agda library, first check that the library has a `*.agda-lib` file. A derivation can then be written using `agdaPackages.mkDerivation`. This has similar arguments to `stdenv.mkDerivation` with the following additions: -+ `everythingFile` can be used to specify the location of the `Everything.agda` file, defaulting to `./Everything.agda`. If this file does not exist then either it should be patched in or the `buildPhase` should be overridden (see below). -+ `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 `${libraryName}.agda-lib`. -### Building Agda packages +* `everythingFile` can be used to specify the location of the `Everything.agda` file, defaulting to `./Everything.agda`. If this file does not exist then either it should be patched in or the `buildPhase` should be overridden (see below). +* `libraryName` should be the name that appears in the `*.agda-lib` file, defaulting to `pname`. +* `libraryFile` should be the file name of the `*.agda-lib` file, defaulting to `${libraryName}.agda-lib`. + +Here is an example `default.nix` + +```nix +{ nixpkgs ? <nixpkgs> }: +with (import nixpkgs {}); +agdaPackages.mkDerivation { + version = "1.0"; + pname = "my-agda-lib"; + src = ./.; + buildInputs = [ + agdaPackages.standard-library + ]; +} +``` + +### Building Agda packages {#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. Additionally, a `preBuild` or `configurePhase` can be used if there are steps that need to be done prior to checking the `Everything.agda` file. `agda` and the Agda libraries contained in `buildInputs` are made available during the build phase. -### Installing Agda packages -The default install phase copies agda source files, agda interface files (`*.agdai`) and `*.agda-lib` files to the output directory. +### Installing Agda packages {#installing-agda-packages} + +The default install phase copies Agda source files, Agda interface files (`*.agdai`) and `*.agda-lib` files to the output directory. This can be overridden. -By default, agda sources are files ending on `.agda`, or literate agda files ending on `.lagda`, `.lagda.tex`, `.lagda.org`, `.lagda.md`, `.lagda.rst`. The list of recognised agda source extensions can be extended by setting the `extraExtensions` config variable. +By default, Agda sources are files ending on `.agda`, or literate Agda files ending on `.lagda`, `.lagda.tex`, `.lagda.org`, `.lagda.md`, `.lagda.rst`. The list of recognised Agda source extensions can be extended by setting the `extraExtensions` config variable. -To add an agda package to `nixpkgs`, the derivation should be written to `pkgs/development/libraries/agda/${library-name}/` and an entry should be added to `pkgs/top-level/agda-packages.nix`. Here it is called in a scope with access to all other agda libraries, so the top line of the `default.nix` can look like: -``` +## Adding Agda packages to Nixpkgs {#adding-agda-packages-to-nixpkgs} + +To add an Agda package to `nixpkgs`, the derivation should be written to `pkgs/development/libraries/agda/${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 { version = "1.5.0"; pname = "iowa-stdlib"; @@ -101,6 +188,7 @@ mkDerivation { ''; } ``` + This library has a file called `.agda-lib`, and so we give an empty string to `libraryFile` as nothing precedes `.agda-lib` in the filename. This file contains `name: IAL-1.3`, and so we let `libraryName = "IAL-1.3"`. This library does not use an `Everything.agda` file and instead has a Makefile, so there is no need to set `everythingFile` and we set a custom `buildPhase`. -When writing an agda package it is essential to make sure that no `.agda-lib` file gets added to the store as a single file (for example by using `writeText`). This causes agda to think that the nix store is a agda library and it will attempt to write to it whenever it typechecks something. See [https://github.com/agda/agda/issues/4613](https://github.com/agda/agda/issues/4613). +When writing an Agda package it is essential to make sure that no `.agda-lib` file gets added to the store as a single file (for example by using `writeText`). This causes Agda to think that the nix store is a Agda library and it will attempt to write to it whenever it typechecks something. See [https://github.com/agda/agda/issues/4613](https://github.com/agda/agda/issues/4613). |