This is my emacs/haskell development environment.

I use both Intero and Dante

• Intero only works with Stack
  • See: https://github.com/cydparser/demo-emacs-haskell/
• Dante works with cabal, nix, stack, etc.

Intero seems to work better with Stack than Dante.

Last Modified : 2017 Oct 26 (Thu) 08:21:13 by Harold Carr.

setup

Get

• .haskell-minimal-init.el
• hc-haskell-dante.el
• hc-haskell-intero.el
• and the files referenced in .haskell-minimal-init.el

from https://github.com/haroldcarr/emacs.

When the following starts, it will ask you whether to use Dante or Intero.

emacs -q -l <path to>/.haskell-minimal-init.el

projectile

project navigation, building, testing, …

Keybindings (subset)

• C-c p ! : projectile-run-shell-command-in-root
• C-c p c : projectile-compile-project
• C-c p f : projectile-find-file
• C-c p k : projectile-kill-buffers
• C-c p t : projectile-toggle-between-implementation-and-test

To see full list, if whick-key is install: press C-c p and wait.

try:

• go to any directory in a project
• C-c p f
• type a filename from anywhere in the project
• use C-p and C-n to navigate list of candidates
• press RET to go to that file

yasnippet / haskell-snippets

some templates (to see full list: M-x yas/describe-tables)

try:

• open new file List.hs
• type mod
• press M-/ (hippie-expand)
• select simple module
• press RET
• press tab to accept default module name (or start typing)

haskell

haskell-hoogle (part of haskell-mode)

search by name

try:

• in a haskell file, point to something provided by external library or GHC
• M-x hayoo (using Hayoo!)
• M-x hoogle (using Hoogle)

search by type

try:

• M-x hayoo or hoogle
• enter : f a -> Maybe c RET

Dante / Intero

view types / info

try:

types

• point to something
• C-c . : dante-type-at
• C-c C-t : intero-type-at

info (shows definition and where defined, even if external)

• point to something
• C-c , : dante-info
• C-c C-i : intero-info

definitions and references

definitions

• point to something
• M-. : jump to definition (both dante and intero)
• M-, : return to previous location (both dante and intero)

references

• point to something
• M-? : xref-find-references (dante : TODO : DOES NOT WORK FOR ME)
• M-? : intero-uses-at (TODO : DOES NOT WORK FOR ME)

apply suggestions / auto-fix

try:

• add the following code to List.hs

    data List a = Cons a (List a) | Nil
      deriving (Eq, Foldable, Show)

• see red squiggly line under Foldable
• C-c ! l : flycheck-list-errors
• says “… You need DeriveFoldable …”
• put cursor on Foldable
• C-c / : dante-auto-fix
• C-c C-r : intero-apply-suggestions
• (inserts appropriate LANGUAGE pragma)

add type info

try:

• add to List.hs

    cdr Nil = Nil
    cdr (Cons _ xs) = xs

• see red squiggly line under cdr
• C-c ! l : flycheck-list-errors
• says “… Top-level binding with no type signature …”
• C-c / : dante-auto-fix
• C-c C-r : intero-apply-suggestions
• (inserts appropriate type signature)

doctest

try:

• add to List.hs

    -- | Returns the first element, if non-empty.
    --
    -- >>> car Nil
    --
    -- >>> car (Cons 'a' Nil)
    car :: List a -> Maybe a
    car xs = case xs of
      Nil      -> Nothing
      Cons x _ -> Just x

• point inside comment
• C-c " : dante-eval-block
• (inserts function call results)

process buffer

If dante starts acting weird, restart it.

M-x dante-list-buffers RET
M-x intero-list-buffers RET
d ;; mark process for deletion
x ;; kill it
q ;; quit process list
M-x dante-restart RET
M-x intero-list-buffers RET

completion via company

try:

• in List.hs
• type : import System.E
• M-n or M-p : move through suggestions
• note: delete E until only : import System.
• now shows all packages in System

projectile / test files

try:

• from List.hs
• C-c p t
• finds and jumps to (or creates) ListSpec.hs

projectile / build and run

• C-c p c : build
• C-c p ! : run

formatting

• M-x haskell-mode-stylish-buffer