Happy Haskell programming on Emacs/Vim

"ghc-mod" is a command to enrich Haskell programming on editors including Emacs and Vim. The ghc-mod package includes the "ghc-mod" command and Emacs front-end.

Emacs front-end is an extension of Haskell mode. They enable to complete Haskell symbols on Emacs and to browse documents of modules. Flymake with GHC/Hlint is also integrated.

Vim plugin is also available from github.

The current package can be found in Hackage. The git repository is on github.

Usage for Emacs

M-C-i

Completes a name of keyword, module, class, function, types, language extensions, GHC flags, etc.

M-/

Completes a name of local symbol.

M-t

Inserts template. In the beginning of a buffer, "module Foo where" is inserted. On the function without signature, inferred type is inserted. On a symbol "foo" without definition, "foo = undefined" is inserted. Original code is replaced with hlint's suggestion if possible.

M-C-d

Browses the local document of the module on the current line (e.g. the import line) on your browser

C-uM-C-d

Browses the Hackage document of the module on the current line (e.g. the import line) on your browser

M-C-m

Loads information of symbols for modules in the current buffer. If you add a new line to import a module, type this. The idle timer executes this command anyway.

C-xC-s

Saves the buffer if necessary and runs syntax check. Also, a timer executes syntax check automatically.

C-cC-c

Toggle GHC and Hlint for syntax check. GHC is used for initial time.

M-n

Goes to the next warning or error.

M-p

Goes to the previous warning or error.

M-?

Displays the warning/error message in the current line.

C-cC-i

Displays the info of this expression in another window.

C-cC-t

Displays the type of this expression in the minibuffer. Type C-cC-t multiple time to enlarge the expression.

C-cC-m

Insert "import Module" for this function. "hoogle" command is required and "hoogle data" should be done beforehand.

Customizing

If you want to specify GHC options from Emacs, set "ghc-ghc-options". The following is an example to specify the "-i" options to GHC.

(setq ghc-ghc-options '("-idir1" "-idir2"))