load the purescript rules and functions:

Adding purescript support to your bazel repo

This repo is the beginnings of support for purescript in Bazel. In order to use this put the following into your WORKSPACE file:

# refer to a githash in this repo:
rules_purescript_version = "38abb155c30502c9996925640b9b8e04bd48d974"

# download the archive:
http_archive(
    name = "io_bazel_rules_purescript",
    url  = "https://github.com/felixmulder/rules_purescript/archive/%s.zip" % rules_purescript_version,
    type = "zip",
    strip_prefix = "rules_purescript-%s" % rules_purescript_version,
)

# load the purescript rules and functions:
load("@io_bazel_rules_purescript//purescript:purescript.bzl", "purescript_toolchain", "purescript_dep")

# downloads the `purs` command:
purescript_toolchain()

# add some dependencies:
purescript_dep(
    name = "purescript_console",
    url = "https://github.com/purescript/purescript-console/archive/v4.1.0.tar.gz",
    sha256 = "5b0d2089e14a3611caf9d397e9dd825fc5c8f39b049d19448c9dbbe7a1b595bf",
    strip_prefix = "purescript-console-4.1.0",
)

purescript_dep(
    name = "purescript_effect",
    url = "https://github.com/purescript/purescript-effect/archive/v2.0.0.tar.gz",
    sha256 = "5254c048102a6f4360a77096c6162722c4c4b2449983f26058d75d4e5be9d301",
    strip_prefix = "purescript-effect-2.0.0",
)

purescript_dep(
    name = "purescript_prelude",
    url = "https://github.com/purescript/purescript-prelude/archive/v4.0.1.tar.gz",
    sha256 = "3b69b111875eb2b915fd7bdf320707ed3d22194d71cd51d25695d22ab06ae6ee",
    strip_prefix = "purescript-prelude-4.0.1",
)

Defining a project

With this in place you can now define a BUILD file for your project:

load("@io_bazel_rules_purescript//purescript:purescript.bzl", "purescript_app", "purescript_test")

dependencies = \
    [ "@purescript_console//:pkg"
    , "@purescript_effect//:pkg"
    , "@purescript_prelude//:pkg"
    ]

# Defines an application with default entrypoint (Main.main):
purescript_app(
    name       = "purs-app",
    visibility = ["//visibility:public"],
    srcs       = glob(["src/**/*.purs"]),
    deps       = dependencies,
)

You can now build your program and run the main function!

If you want to customize the entrypoint, you can do something like:

purescript_app(
    name             = "purs-app",
    visibility       = ["//visibility:public"],
    srcs             = glob(["src/**/*.purs"]),
    deps             = dependencies,
    entry_module     = "MyModule",
    entry_function   = "myFunction",
    entry_parameters = [ "my", "parameters" ],
)

Depending on other Bazel Purescript Projects

Currently this is as simple as adding the label to your project's dependencies. There's a known issue with the way this is currently implemented. Files with the same name will overwrite each other. This is detailed in #4.

Example of depending on other bazel purescript project:

purescript_app(
    name             = "purs-app",
    visibility       = ["//visibility:public"],
    srcs             = glob(["src/**/*.purs"]),
    deps             = [ "//lib:purs-lib" ] + dependencies,
)

Testing

In the same BUILD file, you can define a test module:

purescript_test(
    name = "purs-app-test",
    srcs = glob(["test/**/*.purs"]) + glob(["src/**/*.purs"]),
    deps = dependencies,
)

in the test directory I've created a module like:

module Test.Main where

-- imports omitted

main :: Effect Unit
main = log "Hello test world!"

when you run bazel test on the :purs-app-test project, it should succeed :tada:

NOTE: the default entrypoint for testing is the module Test.Main and the function main. But these can be overwritten:

purescript_test(
    name          = "purs-app-test",
    srcs          = glob(["test/**/*.purs"]) + glob(["src/**/*.purs"]),
    deps          = dependencies,
    main_module   = "MyMainTest.Whatever"
    main_function = "myFun"
)