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spacemacs/contrib/!lang/haskell/README.md
2015-05-25 00:50:38 -04:00

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# Haskell contribution layer for Spacemacs
![logo](img/haskell.png)
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**Table of Contents**
- [Haskell contribution layer for Spacemacs](#haskell-contribution-layer-for-spacemacs)
- [Description](#description)
- [Install](#install)
- [Layer](#layer)
- [Cabal packages](#cabal-packages)
- [OS X](#os-x)
- [Optional extras](#optional-extras)
- [GHCi-ng support](#ghci-ng-support)
- [structured-haskell-mode](#structured-haskell-mode)
- [hindent](#hindent)
- [Key bindings](#key-bindings)
- [-](#-)
- [Debug](#debug)
- [REPL](#repl)
- [Cabal commands](#cabal-commands)
- [Cabal files](#cabal-files)
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## Description
This layer adds support for the [Haskell][] language.
Some features:
- auto-completion with [company-ghc][],
- syntax highlighting for [C-- source][cmm-mode].
**This layer is in construction, it needs your contributions and bug reports.**
## Install
### Layer
To use this contribution add it to your `~/.spacemacs`
```elisp
(setq-default dotspacemacs-configuration-layers '(haskell))
```
### Cabal packages
This layer requires some [cabal][] packages:
- `ghc-mod`
- `hlint`
- `stylish-haskell`
- `hasktags`
To install them, use the following command:
```sh
cabal install stylish-haskell hlint ghc-mod hasktags
```
Then you have to add this path to your system `$PATH` (preferred):
Note that on **Linux** distributions the installed binaries should be in
`~/.cabal/bin` and on **OS X** the binaries are installed in
`/Users/<username>/Library/Haskell/bin`.
```sh
export PATH=~/.cabal/bin/:$PATH
```
_or_ to the Emacs `exec-path` variable in the `dotspacemacs/init` function of
your `.spacemacs` file:
```elisp
(add-to-list 'exec-path "~/.cabal/bin/")
```
**Note:** it is important to add the path in the `dotspacemacs/init` function,
so that the path is added before any layers is loaded.
### OS X
Note that `emacs.app` for OS X does not pick up `$PATH` from `~/.bashrc` or
`~/.zshrc` when launched from outside a terminal.
### Optional extras
The Haskell layer supports some extra features that can be enabled through
layer variables.
#### GHCi-ng support
[ghci-ng][] adds some nice features to `haskell-mode`, and is supported in
Spacemacs by a layer variable:
Follow the instructions to install [ghci-ng][] (remember to add `:set +c`
in `~/.ghci`, next set the layer variable:
```elisp
(setq-default dotspacemacs-configuration-layers
'((haskell :variables haskell-enable-ghci-ng-support t)))
```
Once ghci-ng is enabled, two of the old keybindings are overriden with improved
versions from ghci-ng, and a new keybinding available:
Key Binding | Description
----------------------|------------------------------------------------------------
<kbd>SPC m h t</kbd> | gets the type of the identifier under the cursor or for the active region
<kbd>SPC m g g</kbd> | go to definition
<kbd>SPC m u</kbd> | finds uses of identifier
#### structured-haskell-mode
[structured-haskell-mode][], or shm, replaces default haskell-mode
auto-indentation and adds some nice functionalities.
To enable shm, run `cabal install structured-haskell-mode` and set the layer
variable:
```elisp
(setq-default dotspacemacs-configuration-layers
'((haskell :variables haskell-enable-shm-support t)))
```
After shm has been enabled, some of the evil normal state bindings are overridden:
Key Binding | Description
----------------------|------------------------------------------------------------
<kbd>D</kbd> | `shm/kill-line`
<kbd>R</kbd> | `shm/raise`
<kbd>P</kbd> | `shm/yank`
<kbd>(</kbd> | `shm/forward-node`
<kbd>)</kbd> | `shm/backward-node`
For a nice visualization of these functions, please refer to the github page
for [structured-haskell-mode][].
#### hindent
[hindent][] is an extensible Haskell pretty printer, which let's you
reformat your code. You need to install the executable with `cabal
install hindent`.
To enable it you have to set the variable `haskell-enable-hindent-style`
to a supported style. The available styles are:
- fundamental
- johan-tibell
- chris-done
- andrew-gibiansky
See examples [here][hindent-examples]
```elisp
(setq-default dotspacemacs-configuration-layers
'((haskell :variables haskell-enable-hindent-style "johan-tibell")))
```
## Key bindings
All Haskell specific bindings are prefixed with the major-mode leader
<kbd>SPC m</kbd>.
Top-level commands are prefixed by <kbd>SPC m</kbd>:
Key Binding | Description
----------------------|------------------------------------------------------------
<kbd>SPC m g g</kbd> | go to definition or tag
<kbd>SPC m f</kbd> | format buffer using haskell-stylish
<kbd>SPC m F</kbd> | format declaration using hindent (if enabled)
### Documentation
Documentation commands are prefixed by <kbd>SPC m h</kbd>
Key Binding | Description
----------------------|------------------------------------------------------------
<kbd>SPC m h d</kbd> | find or generate Haddock documentation for the identifier under the cursor
<kbd>SPC m h h</kbd> | do a Hoogle lookup
<kbd>SPC m h i</kbd> | gets information for the identifier under the cursor
<kbd>SPC m h t</kbd> | gets the type of the identifier under the cursor
<kbd>SPC m h y</kbd> | do a Hayoo lookup
### Debug
Debug commands are prefixed by <kbd>SPC m d</kbd>:
Key Binding | Description
----------------------|------------------------------------------------------------
<kbd>SPC m d d </kbd> | start debug process, needs to be run first
<kbd>SPC m d b </kbd> | insert breakpoint at function
<kbd>SPC m d n </kbd> | next breakpoint
<kbd>SPC m d N </kbd> | previous breakpoint
<kbd>SPC m d B </kbd> | delete breakpoint
<kbd>SPC m d c </kbd> | continue current process
<kbd>SPC m d a </kbd> | abandon current process
<kbd>SPC m d r </kbd> | refresh process buffer
### REPL
REPL commands are prefixed by <kbd>SPC m s</kbd>:
Key Binding | Description
----------------------|------------------------------------------------------------
<kbd>SPC m s b</kbd> | load or reload the current buffer into the REPL
<kbd>SPC m s c</kbd> | clear the REPL
<kbd>SPC m s s</kbd> | show the REPL
<kbd>SPC m s S</kbd> | show and switch to the REPL
### Cabal commands
Cabal commands are prefixed by <kbd>SPC m c</kbd>:
Key Binding | Description
----------------------|------------------------------------------------------------
<kbd>SPC m c a</kbd> | cabal actions
<kbd>SPC m c b</kbd> | build the current cabal project, i.e. invoke `cabal build`
<kbd>SPC m c c</kbd> | compile the current project, i.e. invoke `ghc`
<kbd>SPC m c v</kbd> | visit the cabal file
### Cabal files
This commands are available in a cabal file.
Key Binding | Description
----------------------|------------------------------------------------------------
<kbd>SPC m d</kbd> | add a dependency to the project
<kbd>SPC m b</kbd> | go to benchmark section
<kbd>SPC m e</kbd> | go to executable section
<kbd>SPC m t</kbd> | go to test-suite section
<kbd>SPC m m</kbd> | go to exposed modules
<kbd>SPC m l</kbd> | go to libary section
<kbd>SPC m n</kbd> | go to next subsection
<kbd>SPC m p</kbd> | go to previous subsection
<kbd>SPC m N</kbd> | go to next section
<kbd>SPC m P</kbd> | go to previous section
<kbd>SPC m f</kbd> | find or create source-file under the cursor
[Haskell]: https://www.haskell.org/
[cabal]: https://www.haskell.org/cabal/
[cmm-mode]: https://github.com/bgamari/cmm-mode
[company-ghc]: https://github.com/iquiw/company-ghc
[ghci-ng]: https://github.com/chrisdone/ghci-ng
[structured-haskell-mode]: https://github.com/chrisdone/structured-haskell-mode
[hindent]: https://github.com/chrisdone/hindent
[hindent-examples]: https://github.com/chrisdone/hindent#example