Installing and configuring Haskell

cabal VS. stack
Install Haskell compiler and softwares using stack
Install Haskell compiler and softwares using cabal
Verifying the stack and Haskell installation
Configure Emacs for Haskell development
Configure a Haskell project using stack
1. Create a project
2. Build
Configure a Haskell project using IntelliJ IDEA
References

`cabal` VS. `stack`

cabal and stack are two tools one can use to install Glasgow Haskell Compiler (GHC), i.e. the binaries ghc and ghci, and Haskell software packages. stack installs Haskell programs in ~/.stack and cabal installs in ~/.cabal. Using both cabal and stack, or either one of them is possible, but it seems the current general wisdom is that stack is more user friendly especially for beginners. So I chose to uninstall cabal and delete ~/.cabal, and use stack only.

Install Haskell compiler and softwares using `stack`

stack is built on top of cabal (which in turn relies on ghc-pkg), the package management system for Haskell softwares, but is more user friendly in some ways.

Uninstall the ghc installed using the system's package management system

macOS:

    brew uninstall --force cabal-install
    brew uninstall --force ghc

Linux:

    sudo apt-get remove ghc
    sudo apt-get remove cabal-install

Install stack
- macOS:
```
    brew install haskell-stack
```
- Linux: Follow the instruction about installation in the official documentation. Don't just do sudo apt-get install haskell-stack.
Install ghc
```
  stack setup
```
If you want to use binaries installed via stack regularly, put them on path. Run stack path and append the paths of form ~/.stack/.../bin in the output to $PATH in ~/.bashrc.

Install packages using stack:

  stack install ghc-mod
  stack install cabal-install
  stack install hlint
  stack install pandoc
  stack install purescript
  stack install wreq
  stack install lens
  stack install ihaskell        
  stack install projectile
  stack install use-package
  stack install which-key

  stack install apply-refact
  stack install codex
  stack install hasktags

ihaskell: IHaskell, Haskell kernel for Jupyter notebooks.

Install Haskell compiler and softwares using `cabal`

Install ghc and cabal
```
  brew install cabal-install ghc
```

Install packages via cabal

  cabal update
  cabal install happy # 2016-3-5: prerequisite for ghc-mod
  cabal install ghc-mod hlint haskell-docs

Verifying the stack and Haskell installation

cd $HOME
# Assume 'stack setup' has been run.
stack init
stack build --dependencies-only --test

Configure Emacs for Haskell development

Install the following Emacs packages, ideally using the GNU Emacs Lisp Package Archive (see also EmacsWiki: ELPA):

Emacs packages specifically relevant for Haskell:
- haskell-mode
- haskell-snippets
- flycheck-hlint
- intero
Other Emacs packages generally helpful.

Configure a Haskell project using `stack`

Create a project

cd path/to/workspace/
stack new haskell-stack-test-project
cd haskell-stack-test-project
stack setup
stack build --dependencies-only --test

This creates a new project using template ~/.stack/templates/new-template.hsfiles. The project directory structure:

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

Remarks:

app/ contains the source file(s) for more application-specific logic, including a app/Main.hs.
src/ contains the source file(s) for more shareable and general-purpose code.

Build

$ cd path/to/haskell-stack-test-project
$ stack build
haskell-stack-test-project-0.1.0.0: configure
Configuring haskell-stack-test-project-0.1.0.0...
haskell-stack-test-project-0.1.0.0: build
Preprocessing library haskell-stack-test-project-0.1.0.0...
[1 of 1] Compiling Lib              ( src/Lib.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.5.0/build/Lib.o )
In-place registering haskell-stack-test-project-0.1.0.0...
Preprocessing executable 'haskell-stack-test-project-exe' for
haskell-stack-test-project-0.1.0.0...
[1 of 1] Compiling Main             ( app/Main.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.5.0/build/haskell-stack-test-project-exe/haskell-stack-test-project-exe-tmp/Main.o )
Linking .stack-work/dist/x86_64-osx/Cabal-1.22.5.0/build/haskell-stack-test-project-exe/haskell-stack-test-project-exe ...
haskell-stack-test-project-0.1.0.0: copy/register
Installing library in
/Users/meng/Dropbox/WorkSpace-Dropbox/Computing/repo-meng-lib/Haskell/haskell-stack-test-project/.stack-work/install/x86_64-osx/lts-5.5/7.10.3/lib/x86_64-osx-ghc-7.10.3/haskell-stack-test-project-0.1.0.0-BCjrGi4SAkj4MdkT4tD42y
Installing executable(s) in
/Users/meng/Dropbox/WorkSpace-Dropbox/Computing/repo-meng-lib/Haskell/haskell-stack-test-project/.stack-work/install/x86_64-osx/lts-5.5/7.10.3/bin
Registering haskell-stack-test-project-0.1.0.0...

The path to the built executable is contained in the line starting with Linking: Linking .stack-work/dist/x86_64-osx/Cabal-1.22.5.0/build/haskell-stack-test-project-exe/haskell-stack-test-project-exe ....

$ .stack-work/dist/x86_64-osx/Cabal-1.22.5.0/build/haskell-stack-test-project-exe/haskell-stack-test-project-exe
someFunc