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Haskell contribution layer for Spacemacs
Table of Contents
Description
This layer adds support for the Haskell language.
Some features:
- auto-completion with company-ghc,
- syntax highlighting for C-- source.
This layer is in construction, it needs your contributions and bug reports.
Install
Layer
To use this contribution add it to your ~/.spacemacs
(setq-default dotspacemacs-configuration-layers '(haskell))
Cabal packages
This layer requires some cabal packages:
ghc-modhlintstylish-haskellhasktags
To install them, use the following command:
cabal install stylish-haskell hlint ghc-mod hasktags
Then you have to add this path to your system $PATH (preferred):
Note that on Linux distributions the installed binaries should be in
~/.cabal/bin and on OS X the binaries are installed in
/Users/<username>/Library/Haskell/bin.
export PATH=~/.cabal/bin/:$PATH
or to the Emacs exec-path variable in the dotspacemacs/init function of
your .spacemacs file:
(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:
(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
----------------------|------------------------------------------------------------ SPC m h t | gets the type of the identifier under the cursor or for the active region SPC m g g | go to definition SPC m u | 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:
(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
----------------------|------------------------------------------------------------
D | shm/kill-line
R | shm/raise
P | shm/yank
( | shm/forward-node
) | 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
(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 SPC m.
Top-level commands are prefixed by SPC m:
Key Binding | Description
----------------------|------------------------------------------------------------ SPC m g g | go to definition or tag SPC m f | format buffer using haskell-stylish SPC m F | format declaration using hindent (if enabled)
Documentation
Documentation commands are prefixed by SPC m h
Key Binding | Description
----------------------|------------------------------------------------------------ SPC m h d | find or generate Haddock documentation for the identifier under the cursor SPC m h h | do a Hoogle lookup SPC m h i | gets information for the identifier under the cursor SPC m h t | gets the type of the identifier under the cursor SPC m h y | do a Hayoo lookup
Debug
Debug commands are prefixed by SPC m d:
Key Binding | Description
----------------------|------------------------------------------------------------ SPC m d d | start debug process, needs to be run first SPC m d b | insert breakpoint at function SPC m d n | next breakpoint SPC m d N | previous breakpoint SPC m d B | delete breakpoint SPC m d c | continue current process SPC m d a | abandon current process SPC m d r | refresh process buffer
REPL
REPL commands are prefixed by SPC m s:
Key Binding | Description
----------------------|------------------------------------------------------------ SPC m s b | load or reload the current buffer into the REPL SPC m s c | clear the REPL SPC m s s | show the REPL SPC m s S | show and switch to the REPL
Cabal commands
Cabal commands are prefixed by SPC m c:
Key Binding | Description
----------------------|------------------------------------------------------------
SPC m c a | cabal actions
SPC m c b | build the current cabal project, i.e. invoke cabal build
SPC m c c | compile the current project, i.e. invoke ghc
SPC m c v | visit the cabal file
Cabal files
This commands are available in a cabal file.
Key Binding | Description
----------------------|------------------------------------------------------------ SPC m d | add a dependency to the project SPC m b | go to benchmark section SPC m e | go to executable section SPC m t | go to test-suite section SPC m m | go to exposed modules SPC m l | go to libary section SPC m n | go to next subsection SPC m p | go to previous subsection SPC m N | go to next section SPC m P | go to previous section SPC m f | find or create source-file under the cursor