#+TITLE: Purescript layer

[[file:img/purescript-logo.png]]

* Table of Contents                                         :TOC_4_gh:noexport:
 - [[#description][Description]]
 - [[#install][Install]]
 - [[#key-bindings][Key bindings]]
   - [[#purescript][Purescript]]
     - [[#imports][Imports]]
     - [[#psc-ide][psc-ide]]
   - [[#repl][REPL]]
 - [[#layer-variables][Layer Variables]]
   - [[#purescript-add-import-on-completion-default-t-][~purescript-add-import-on-completion (default t)~ ]]
   - [[#purescript-enable-rebuild-on-save-default-nil][~purescript-enable-rebuild-on-save (default nil)~]]

* Description

This layer provides basic Purescript editing support for spacemacs
thanks to the following packages:
- [[https://github.com/dysinger/purescript-mode][purescript-mode]]
- [[https://github.com/ardumont/emacs-psci][psci]]
- [[https://github.com/epost/psc-ide-emacs][psc-ide-emacs]]

* Install
To use this configuration layer, add it to your =~/.spacemacs=. You will need to
add =purescript= to the existing =dotspacemacs-configuration-layers= list in this
file.

You'll also need to make sure the PureScript compiler and its associated
binaries (psc-ide-server, psci,...) are on your path. Installation instructions
can be found [[http://www.purescript.org/download/][here]].

* Key bindings
  
** Purescript

*** Imports

| Key Binding | Description                                                   |
|-------------+---------------------------------------------------------------|
| ~SPC m i =~ | Format imports                                                |
| ~SPC m i \~ | Return to where you were editing before navigating to imports |
| ~SPC m i a~ | Align imports                                                 |
| ~SPC m i n~ | Navigate to the imports                                       |

*** psc-ide

| Key Binding   | Description                                                               |
|---------------+---------------------------------------------------------------------------|
| ~SPC m m s~   | Start psc-ide-server                                                      |
| ~SPC m m l~   | Load definitions for the modules inside your project                      |
| ~SPC m h t~   | Show type at point                                                        |
| ~SPC m m b~   | Rebuilds the current file and displays any warnings or errors             |
| ~SPC m m i a~ | Add an import for the identifier at the current cursor position           |
| ~SPC m m i s~ | Inserts a suggestion for the warning/error at the current cursor position |
| ~SPC m m t~   | Add a new clause for the function signature at point                      |
| ~SPC m m c s~ | Casesplits on the identifier at the current cursor position               |
| ~SPC m m q~   | Quit the current psc-ide-server                                           |
| ~SPC m m L~   | Load a specific module (This is mostly used for troubleshooting)          |


** REPL

[[https://github.com/ardumont/emacs-psci][psci]] provides a very basic REPL for purescript. The following key
bindings are available:

| Key Binding | Description                                                                      |
|-------------+----------------------------------------------------------------------------------|
| ~SPC m s b~ | Equivalent of =:m /path/to/current/module/file.purs= - Load <file> for importing |
| ~SPC m s i~ | Launch a psci console buffer                                                     |
| ~SPC m s m~ | Equivalent of =:i your.current.module.name= - Import <module> for use in PSCI    |
| ~SPC m s p~ | Load or reload files defined in the project file .psci                           |
* Layer Variables

** ~purescript-add-import-on-completion (default t)~ 
   If you set this to nil, psc-ide will stop adding imports on completion

** ~purescript-enable-rebuild-on-save (default nil)~
   If you set this to non-nil, you will get a popup buffer showing you your current
   warnings/errors one at a time. This is primarily meant as an alternative to
   using flycheck.