Haskell test

Haskell project for Haskell development tool testing.

---

• Tool installations
• How to start development

---

Tools

You may need some development libraries in the system for tool compilations. It is a good idea to try to install all tools before starting IDEA plugin. When all builds are successful you are ready to try the plugin.

Additional packages (Debian)

• libgmp-dev
• libtinfo-dev

Some common info:

• https://www.haskell.org/downloads/
• https://www.stackage.org/
• https://www.haskell.org/platform/

Stack

Stack is a cross-platform program for developing Haskell projects. It is aimed at Haskellers both new and experienced.

Features:

• Installing GHC automatically, in an isolated location.
• Installing packages needed for your project.
• Building your project.
• Testing your project.
• Benchmarking your project.

https://docs.haskellstack.org/en/stable/README/

Quick Start Guide

Stack configuration:

https://docs.haskellstack.org/en/stable/yaml_configuration/

Start your new project:

stack new my-project
cd my-project
stack setup
stack build
stack exec my-project-exe

• The stack new command will create a new directory containing all the needed files to start a project correctly.
• The stack setup will download the compiler if necessary in an isolated location (default ~/.stack) that won't interfere with any system-level installations. (For information on installation paths, please use the stack path command.).
• The stack build command will build the minimal project.
• stack exec my-project-exe will execute the command.
• If you just want to install an executable using stack, then all you have to do is stack install <package-name>.

If you want to launch a REPL:

stack ghci

Run stack for a complete list of commands.

Workflow

The stack new command should have created the following files:

.
├── LICENSE
├── Setup.hs
├── app
│   └── Main.hs
├── my-project.cabal
├── src
│   └── Lib.hs
├── stack.yaml
└── test
    └── Spec.hs

    3 directories, 7 files

So to manage your library:

1. Edit files in the src/ directory.

   The app directory should preferably contain only files related to executables.

2. If you need to include another library (for example the package text):

   • Add the package text to the file my-project.cabal in the section build-depends: ....
   • Run stack build another time.

3. If you get an error that tells you your package isn't in the LTS. Just try to add a new version in the stack.yaml file in the extra-deps section.

That was a really fast introduction on how to start to code in Haskell using stack. If you want to go further, we highly recommend you to read the stack guide.

Hindent

Haskell pretty printer.

Currently (8 Apr 2020) Hindent looks unmaintained and it's not possible to build it with newer GHC. Build with older version works:

stack --resolver lts-14.22 install hindent

Install:

$ stack install hindent
...
hindent-4.6.4: configure
hindent-4.6.4: build
hindent-4.6.4: copy/register
Completed 32 action(s).

Copied executables to /home/user/.local/bin:
- hindent
- hindent-generate-tests

https://github.com/commercialhaskell/hindent

Stylish-haskell

A simple Haskell code prettifier. The goal is not to format all of the code in a file, since I find those kind of tools often "get in the way". However, manually cleaning up import statements etc. gets tedious very quickly.

This tool tries to help where necessary without getting in the way.

Install:

$ stack install stylish-haskell
...
stylish-haskell-0.6.1.0: configure
stylish-haskell-0.6.1.0: build
stylish-haskell-0.6.1.0: copy/register
Completed 14 action(s).

Copied executables to /home/user/.local/bin:
- stylish-haskell

https://github.com/jaspervdj/stylish-haskell

Intero

Complete interactive development program for Haskell.

Current (8 Apr 2020) version needs GHC version 8.6.5 at max. You can use the command below if necessary:

stack --resolver lts-14.27 install intero

Install:

$ stack install intero
Using latest snapshot resolver: lts-7.14
Writing implicit global project config file to: /home/user/.stack/global-project/stack.yaml
Note: You can change the snapshot via the resolver field there.
ghc-paths-0.1.0.9: download
ghc-paths-0.1.0.9: configure
...

Copied executables to /home/user/.local/bin:
- intero

https://github.com/commercialhaskell/intero

Hoogle

Hoogle is a Haskell API search engine, which allows you to search many standard Haskell libraries by either function name, or by approximate type signature.

Install:

$ stack install hoogle
...

Copied executables to /home/user/.local/bin:
- hoogle

https://www.haskell.org/hoogle/

IntelliJ-Haskell

Really good IntelliJ plugin for Haskell.

This plugin depends mainly on Stack and Intero. It can create new Stack projects (by using template hspec) and import existing Stack projects.

http://rikvdkleij.github.io/intellij-haskell/

How to start development

You may need some development libraries for building all tools. So check the build error output and install necessary dev libraries.

Stack

You need to install Stack first. Documentation

IntelliJ-Haskell

Then you need IDEA plugin. If you already use any Haskell plugin, uninstall it. For the latest instructions see project readme.

Download test project

For testing your setup you can download this repository and import to IDEA.

Clone repository.

$ git clone https://github.com/dvoraka/hstest.git
Cloning into 'hstest'...
remote: Counting objects: 36, done.
remote: Compressing objects: 100% (21/21), done.
remote: Total 36 (delta 8), reused 33 (delta 5), pack-reused 0
Receiving objects: 100% (36/36), 5.76 KiB | 0 bytes/s, done.
Resolving deltas: 100% (8/8), done.
Checking connectivity... done.
$

Test Stack from a command line

Change directory to the cloned repository.

$ cd hstest
$

Run stack setup command. The output can be different when you run it right after the fresh Stack installation.

$ stack setup
stack will use a sandboxed GHC it installed
For more information on paths, see 'stack path' and 'stack exec env'
To use this GHC and packages outside of a project, consider using:
stack ghc, stack ghci, stack runghc, or stack exec
$

Run stack build command.

$ stack build
hstest-0.1.0.0: configure
Configuring hstest-0.1.0.0...
hstest-0.1.0.0: build
Preprocessing library hstest-0.1.0.0...
[1 of 2] Compiling Input            ( src/Input.hs, .stack-work/dist/x86_64-linux/Cabal-1.24.0.0/build/Input.o )
[2 of 2] Compiling Data.String.Strip ( src/Data/String/Strip.hs, .stack-work/dist/x86_64-linux/Cabal-1.24.0.0/build/Data/String/Strip.o )
Preprocessing executable 'hstest' for hstest-0.1.0.0...
[1 of 1] Compiling Main             ( app/Main.hs, .stack-work/dist/x86_64-linux/Cabal-1.24.0.0/build/hstest/hstest-tmp/Main.o )
Linking .stack-work/dist/x86_64-linux/Cabal-1.24.0.0/build/hstest/hstest ...
hstest-0.1.0.0: copy/register
Installing library in
/home/user/hstest/.stack-work/install/x86_64-linux/lts-7.14/8.0.1/lib/x86_64-linux-ghc-8.0.1/hstest-0.1.0.0-AdhbzLPXl4DBYfJor6h9HV
Installing executable(s) in
/home/user/hstest/.stack-work/install/x86_64-linux/lts-7.14/8.0.1/bin
Registering hstest-0.1.0.0...
$

Run project.

$ stack exec hstest-exe
What is your name?
John
Hello, John!
$

If everything runs, you have Stack prepared.

Development

You can directly play with your own code without building any new project in Playground.hs file. Edit the file and then run:

$ stack ghci
Using main module: 1. Package `hstest' component hstest:exe:hstest-exe with main-is file: /home/user/hstest/app/Main.hs
hstest> configure (lib + exe)
Configuring hstest-0.1.0.0...
hstest> initial-build-steps (lib + exe)
The following GHC options are incompatible with GHCi and have not been passed to it: -threaded
Configuring GHCi with the following packages: hstest
GHCi, version 8.0.1: http://www.haskell.org/ghc/  :? for help
[1 of 4] Compiling Playground       ( /home/user/hstest/src/Playground.hs, interpreted ) [flags changed]
[2 of 4] Compiling Input            ( /home/user/hstest/src/Input.hs, interpreted ) [flags changed]
[3 of 4] Compiling Main             ( /home/user/hstest/app/Main.hs, interpreted ) [Input changed]
[4 of 4] Compiling Data.String.Strip ( /home/user/hstest/src/Data/String/Strip.hs, interpreted ) [flags changed]
Ok, modules loaded: Data.String.Strip, Input, Playground, Main.
Loaded GHCi configuration from /tmp/haskell-stack-ghci/a3568cd9/ghci-script
*Main Data.String.Strip Input Playground>

And your code is accessible in the interactive environment.