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;;; inf-haskell.el --- Interaction with an inferior Haskell process.
;; Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
;; Author: Stefan Monnier <>
;; Keywords: Haskell
;; This file is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 3, or (at your option)
;; any later version.
;; This file is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING. If not, write to
;; the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
;;; Commentary:
;; The code is made of 2 parts: a major mode for the buffer that holds the
;; inferior process's session and a minor mode for use in source buffers.
;; Todo:
;; - Check out Shim for ideas.
;; - i-h-load-buffer and i-h-send-region.
;;; Code:
(require 'comint)
(require 'shell) ;For directory tracking.
(require 'compile)
(require 'haskell-mode)
(eval-when-compile (require 'cl))
;; XEmacs compatibility.
(unless (fboundp 'subst-char-in-string)
(defun subst-char-in-string (fromchar tochar string &optional inplace)
;; This is Haskell-mode, we don't want no stinkin' `aset'.
(apply 'string (mapcar (lambda (c) (if (eq c fromchar) tochar c)) string))))
(unless (fboundp 'make-temp-file)
(defun make-temp-file (prefix &optional dir-flag)
(catch 'done
(while t
(let ((f (make-temp-name (expand-file-name prefix (temp-directory)))))
(condition-case ()
(if dir-flag (make-directory f)
(write-region "" nil f nil 'silent nil))
(throw 'done f))
(file-already-exists t)))))))
(unless (fboundp 'replace-regexp-in-string)
(defun replace-regexp-in-string (regexp rep string)
(replace-in-string string regexp rep)))
;; Here I depart from the inferior-haskell- prefix.
;; Not sure if it's a good idea.
(defcustom haskell-program-name
;; Arbitrarily give preference to hugs over ghci.
(or (cond
((not (fboundp 'executable-find)) nil)
((executable-find "hugs") "hugs \"+.\"")
((executable-find "ghci") "ghci"))
"hugs \"+.\"")
"The name of the command to start the inferior Haskell process.
The command can include arguments."
;; Custom only supports the :options keyword for a few types, e.g. not
;; for string.
;; :options '("hugs \"+.\"" "ghci")
:group 'haskell
:type '(choice string (repeat string)))
(defconst inferior-haskell-info-xref-re
"\t-- Defined at \\(.+\\):\\([0-9]+\\):\\([0-9]+\\)\\(?:-\\([0-9]+\\)\\)?$")
(defconst inferior-haskell-module-re
"\t-- Defined in \\(.+\\)$"
"Regular expression for matching module names in :info.")
(defconst inferior-haskell-error-regexp-alist
;; The format of error messages used by Hugs.
`(("^ERROR \"\\(.+?\\)\"\\(:\\| line \\)\\([0-9]+\\) - " 1 3)
;; Format of error messages used by GHCi.
("^\\(.+?\\):\\([0-9]+\\):\\(\\([0-9]+\\):\\)?\\( \\|\n *\\)\\(Warning\\)?"
1 2 4 ,@(if (fboundp 'compilation-fake-loc)
'((6) nil (5 '(face nil font-lock-multiline t)))))
;; Runtime exceptions, from ghci.
("^\\*\\*\\* Exception: \\(.+?\\):(\\([0-9]+\\),\\([0-9]+\\))-(\\([0-9]+\\),\\([0-9]+\\)): .*"
1 ,@(if (fboundp 'compilation-fake-loc) '((2 . 4) (3 . 5)) '(2 3)))
;; GHCi uses two different forms for line/col ranges, depending on
;; whether it's all on the same line or not :-( In Emacs-23, I could use
;; explicitly numbered subgroups to merge the two patterns.
("^\\*\\*\\* Exception: \\(.+?\\):\\([0-9]+\\):\\([0-9]+\\)-\\([0-9]+\\): .*"
1 2 ,(if (fboundp 'compilation-fake-loc) '(3 . 4) 3))
;; Info messages. Not errors per se.
,@(when (fboundp 'compilation-fake-loc)
`(;; Other GHCi patterns used in type errors.
("^[ \t]+at \\(.+\\):\\([0-9]+\\):\\([0-9]+\\)-\\([0-9]+\\)$"
1 2 (3 . 4) 0)
;; Foo.hs:318:80:
;; Ambiguous occurrence `Bar'
;; It could refer to either `Bar', defined at Zork.hs:311:5
;; or `Bar', imported from Bars at Frob.hs:32:0-16
;; (defined at Location.hs:97:5)
("[ (]defined at \\(.+\\):\\([0-9]+\\):\\([0-9]+\\))?$" 1 2 3 0)
("imported from .* at \\(.+\\):\\([0-9]+\\):\\([0-9]+\\)-\\([0-9]+\\)$"
1 2 (3 . 4) 0)
;; Info xrefs.
(,inferior-haskell-info-xref-re 1 2 (3 . 4) 0))))
"Regexps for error messages generated by inferior Haskell processes.
The format should be the same as for `compilation-error-regexp-alist'.")
(defcustom inferior-haskell-find-project-root t
"If non-nil, try and find the project root directory of this file.
This will either look for a Cabal file or a \"module\" statement in the file."
:type 'boolean)
(define-derived-mode inferior-haskell-mode comint-mode "Inf-Haskell"
"Major mode for interacting with an inferior Haskell process."
(set (make-local-variable 'comint-prompt-regexp)
"^\\*?[A-Z][\\._a-zA-Z0-9]*\\( \\*?[A-Z][\\._a-zA-Z0-9]*\\)*> ")
(set (make-local-variable 'comint-input-autoexpand) nil)
(add-hook 'comint-output-filter-functions 'inferior-haskell-spot-prompt nil t)
;; Setup directory tracking.
(set (make-local-variable 'shell-cd-regexp) ":cd")
(condition-case nil
(shell-dirtrack-mode 1)
(error ;The minor mode function may not exist or not accept an arg.
(set (make-local-variable 'shell-dirtrackp) t)
(add-hook 'comint-input-filter-functions 'shell-directory-tracker
nil 'local)))
;; Setup `compile' support so you can just use C-x ` and friends.
(set (make-local-variable 'compilation-error-regexp-alist)
(set (make-local-variable 'compilation-first-column) 0) ;GHCI counts from 0.
(if (and (not (boundp 'minor-mode-overriding-map-alist))
(fboundp 'compilation-shell-minor-mode))
;; If we can't remove compilation-minor-mode bindings, at least try to
;; use compilation-shell-minor-mode, so there are fewer
;; annoying bindings.
(compilation-shell-minor-mode 1)
;; Else just use compilation-minor-mode but without its bindings because
;; things like mouse-2 are simply too annoying.
(compilation-minor-mode 1)
(let ((map (make-sparse-keymap)))
(dolist (keys '([menu-bar] [follow-link]))
;; Preserve some of the bindings.
(define-key map keys (lookup-key compilation-minor-mode-map keys)))
(add-to-list 'minor-mode-overriding-map-alist
(cons 'compilation-minor-mode map)))))
(defun inferior-haskell-string-to-strings (string)
"Split the STRING into a list of strings."
(let ((i (string-match "[\"]" string)))
(if (null i) (split-string string) ; no quoting: easy
(append (unless (eq i 0) (split-string (substring string 0 i)))
(let ((rfs (read-from-string string i)))
(cons (car rfs)
(substring string (cdr rfs)))))))))
(defun inferior-haskell-command (arg)
(if (null arg) haskell-program-name
(read-string "Command to run haskell: " haskell-program-name))))
(defvar inferior-haskell-buffer nil
"The buffer in which the inferior process is running.")
(defun inferior-haskell-start-process (command)
"Start an inferior haskell process.
With universal prefix \\[universal-argument], prompts for a COMMAND,
otherwise uses `haskell-program-name'.
It runs the hook `inferior-haskell-hook' after starting the process and
setting up the inferior-haskell buffer."
(interactive (list (inferior-haskell-command current-prefix-arg)))
(setq inferior-haskell-buffer
(apply 'make-comint "haskell" (car command) nil (cdr command)))
(with-current-buffer inferior-haskell-buffer
(run-hooks 'inferior-haskell-hook)))
(defun inferior-haskell-process (&optional arg)
(or (if (buffer-live-p inferior-haskell-buffer)
(get-buffer-process inferior-haskell-buffer))
(let ((current-prefix-arg arg))
(call-interactively 'inferior-haskell-start-process))
;; Try again.
(inferior-haskell-process arg))))
(defalias 'run-haskell 'switch-to-haskell)
(defun switch-to-haskell (&optional arg)
"Show the inferior-haskell buffer. Start the process if needed."
(interactive "P")
(let ((proc (inferior-haskell-process arg)))
(pop-to-buffer (process-buffer proc))))
(unless (fboundp 'with-selected-window)
(defmacro with-selected-window (win &rest body)
(select-window ,win)
(defcustom inferior-haskell-wait-and-jump nil
"If non-nil, wait for file loading to terminate and jump to the error."
:type 'boolean
:group 'haskell)
(defvar inferior-haskell-seen-prompt nil)
(make-variable-buffer-local 'inferior-haskell-seen-prompt)
(defun inferior-haskell-spot-prompt (string)
(let ((proc (get-buffer-process (current-buffer))))
(when proc
(goto-char (process-mark proc))
(if (re-search-backward comint-prompt-regexp
(line-beginning-position) t)
(setq inferior-haskell-seen-prompt t))))))
(defun inferior-haskell-wait-for-prompt (proc &optional timeout)
"Wait until PROC sends us a prompt.
The process PROC should be associated to a comint buffer."
(with-current-buffer (process-buffer proc)
(while (progn
(goto-char comint-last-input-end)
(not (or inferior-haskell-seen-prompt
(setq inferior-haskell-seen-prompt
(re-search-forward comint-prompt-regexp nil t))
(not (accept-process-output proc timeout))))))
(unless inferior-haskell-seen-prompt
(error "Can't find the prompt."))))
(defvar inferior-haskell-cabal-buffer nil)
(defun inferior-haskell-cabal-of-buf (buf)
(require 'haskell-cabal)
(with-current-buffer buf
(or (and (buffer-live-p inferior-haskell-cabal-buffer)
(and (not (local-variable-p 'inferior-haskell-cabal-buffer
;; XEmacs needs this argument.
(set (make-local-variable 'inferior-haskell-cabal-buffer)
(defun inferior-haskell-find-project-root (buf)
(with-current-buffer buf
(let ((cabal (inferior-haskell-cabal-of-buf buf)))
(or (when cabal
(with-current-buffer cabal
(let ((hsd (haskell-cabal-get-setting "hs-source-dirs")))
(if (null hsd)
;; If there's a Cabal file with no Hs-Source-Dirs, then
;; just use the Cabal file's directory.
;; If there is an HSD, then check that it's an existing
;; dir (otherwise, it may be a list of dirs and we don't
;; know what to do with those). If it doesn't exist, then
;; give up.
(if (file-directory-p hsd) (expand-file-name hsd))))))
;; If there's no Cabal file or it's not helpful, try to look for
;; a "module" statement and count the number of "." in the
;; module name.
(goto-char (point-min))
(let ((case-fold-search nil))
(when (re-search-forward
"^module[ \t]+\\([^- \t\n]+\\.[^- \t\n]+\\)[ \t]+where\\>" nil t)
(let* ((dir default-directory)
(module (match-string 1))
(pos 0))
(while (string-match "\\." module pos)
(setq pos (match-end 0))
(setq dir (expand-file-name ".." dir)))
;; Let's check that the module name matches the file name,
;; otherwise the project root is probably not what we think.
(if (eq t (compare-strings
(file-name-sans-extension buffer-file-name)
nil nil
(replace-regexp-in-string "\\." "/" module)
nil nil t))
;; If they're not equal, it means the local directory
;; hierarchy doesn't match the module name. This seems
;; odd, so let's warn the user about it. May help us
;; debug this code as well.
(message "Ignoring inconsistent `module' info: %s in %s"
module buffer-file-name)
(defun inferior-haskell-load-file (&optional reload)
"Pass the current buffer's file to the inferior haskell process.
If prefix arg \\[universal-argument] is given, just reload the previous file."
(interactive "P")
;; Save first, so we're sure that `buffer-file-name' is non-nil afterward.
(let ((buf (current-buffer))
(file buffer-file-name)
(proc (inferior-haskell-process)))
(with-current-buffer (process-buffer proc)
(let ((parsing-end (marker-position (process-mark proc)))
;; Go to the root of the Cabal project, if applicable.
(when (and inferior-haskell-find-project-root
(setq root (inferior-haskell-find-project-root buf)))
;; Not sure if it's useful/needed and if it actually works.
(unless (equal default-directory root)
(setq default-directory root)
proc (concat ":cd " default-directory)))
(setq file (file-relative-name file)))
proc (if reload ":reload"
(concat ":load \""
;; Espace the backslashes that may occur in file names.
(replace-regexp-in-string "[\\\"]" "\\\\\&" file)
;; Move the parsing-end marker *after* sending the command so
;; that it doesn't point just to the insertion point.
;; Otherwise insertion may move the marker (if done with
;; insert-before-markers) and we'd then miss some errors.
(if (boundp 'compilation-parsing-end)
(if (markerp compilation-parsing-end)
(set-marker compilation-parsing-end parsing-end)
(setq compilation-parsing-end parsing-end))))
(with-selected-window (display-buffer (current-buffer))
(goto-char (point-max)))
;; Use compilation-auto-jump-to-first-error if available.
;; (if (and (boundp 'compilation-auto-jump-to-first-error)
;; compilation-auto-jump-to-first-error
;; (boundp 'compilation-auto-jump-to-next))
;; (setq compilation-auto-jump-to-next t)
(when inferior-haskell-wait-and-jump
(inferior-haskell-wait-for-prompt proc)
(ignore-errors ;Don't beep if there were no errors.
(next-error)))))) ;; )
(defvar inferior-haskell-run-command ":main")
(defun inferior-haskell-load-and-run (command)
"Pass the current buffer's file to haskell and then run a COMMAND."
(if (and inferior-haskell-run-command (not current-prefix-arg))
(read-string "Command to run: " nil nil inferior-haskell-run-command))))
(setq inferior-haskell-run-command command)
(let* ((inferior-haskell-errors nil)
(neh (lambda () (setq inferior-haskell-errors t))))
(let ((inferior-haskell-wait-and-jump t))
(add-hook 'next-error-hook neh)
(remove-hook 'next-error-hook neh))
(unless inferior-haskell-errors
(inferior-haskell-send-command (inferior-haskell-process) command)
(defun inferior-haskell-send-command (proc str)
(setq str (concat str "\n"))
(with-current-buffer (process-buffer proc)
(inferior-haskell-wait-for-prompt proc)
(goto-char (process-mark proc))
(insert-before-markers str)
(move-marker comint-last-input-end (point))
(setq inferior-haskell-seen-prompt nil)
(comint-send-string proc str)))
(defun inferior-haskell-reload-file ()
"Tell the inferior haskell process to reread the current buffer's file."
(inferior-haskell-load-file 'reload))
(defun inferior-haskell-type (expr &optional insert-value)
"Query the haskell process for the type of the given expression.
If optional argument `insert-value' is non-nil, insert the type above point
in the buffer. This can be done interactively with the \\[universal-argument] prefix.
The returned info is cached for reuse by `haskell-doc-mode'."
(let ((sym (haskell-ident-at-point)))
(list (read-string (if (> (length sym) 0)
(format "Show type of (default %s): " sym)
"Show type of: ")
nil nil sym)
(if (string-match "\\`\\s_+\\'" expr) (setq expr (concat "(" expr ")")))
(let* ((proc (inferior-haskell-process))
(with-current-buffer (process-buffer proc)
(let ((parsing-end ; Remember previous spot.
(marker-position (process-mark proc))))
(inferior-haskell-send-command proc (concat ":type " expr))
;; Find new point.
(inferior-haskell-wait-for-prompt proc)
(goto-char (point-max))
;; Back up to the previous end-of-line.
(end-of-line 0)
;; Extract the type output
(save-excursion (goto-char parsing-end)
(line-beginning-position 2))
(if (not (string-match (concat "^\\(" (regexp-quote expr) "[ \t\n]+::[ \t\n]*\\(.\\|\n\\)*\\)")
(error "No type info: %s" type)
(setf type (match-string 1 type))
;; Cache for reuse by haskell-doc.
(when (and (boundp 'haskell-doc-mode) haskell-doc-mode
(boundp 'haskell-doc-user-defined-ids)
;; Haskell-doc only works for idents, not arbitrary expr.
(string-match "\\`(?\\(\\s_+\\|\\(\\sw\\|\\s'\\)+\\)?[ \t]*::[ \t]*"
(let ((sym (match-string 1 type)))
(setq haskell-doc-user-defined-ids
(cons (cons sym (substring type (match-end 0)))
(delq (assoc sym haskell-doc-user-defined-ids)
(if (interactive-p) (message "%s" type))
(when insert-value
(insert type "\n"))
(defun inferior-haskell-info (sym)
"Query the haskell process for the info of the given expression."
(let ((sym (haskell-ident-at-point)))
(list (read-string (if (> (length sym) 0)
(format "Show info of (default %s): " sym)
"Show info of: ")
nil nil sym))))
(let ((proc (inferior-haskell-process)))
(with-current-buffer (process-buffer proc)
(let ((parsing-end ; Remember previous spot.
(marker-position (process-mark proc))))
(inferior-haskell-send-command proc (concat ":info " sym))
;; Find new point.
(inferior-haskell-wait-for-prompt proc)
(goto-char (point-max))
;; Move to previous end-of-line
(end-of-line 0)
(let ((result
(save-excursion (goto-char parsing-end)
(line-beginning-position 2))
;; Move back to end of process buffer
(goto-char (point-max))
(if (interactive-p) (message "%s" result))
(defun inferior-haskell-find-definition (sym)
"Attempt to locate and jump to the definition of the given expression."
(let ((sym (haskell-ident-at-point)))
(list (read-string (if (> (length sym) 0)
(format "Find definition of (default %s): " sym)
"Find definition of: ")
nil nil sym))))
(let ((info (inferior-haskell-info sym)))
(if (not (string-match inferior-haskell-info-xref-re info))
(error "No source information available")
(let ((file (match-string-no-properties 1 info))
(line (string-to-number
(match-string-no-properties 2 info)))
(col (string-to-number
(match-string-no-properties 3 info))))
(when file
(with-current-buffer (process-buffer (inferior-haskell-process))
;; The file name is relative to the process's cwd.
(setq file (expand-file-name file)))
;; Push current location marker on the ring used by `find-tag'
(require 'etags)
(ring-insert find-tag-marker-ring (point-marker))
(pop-to-buffer (find-file-noselect file))
(when line
(goto-line line)
(when col (move-to-column col))))))))
;;; Functions to find the documentation of a given function.
;; TODO for this section:
;; * Support fetching of local Haddock docs pulled directly from source files.
;; * Display docs locally? w3m?
(defcustom inferior-haskell-use-web-docs
"Whether to use the online documentation. Possible values:
`never', meaning always use local documentation, unless the local
file doesn't exist, when do nothing, `fallback', which means only
use the online documentation when the local file doesn't exist,
or `always', meaning always use the online documentation,
regardless of existance of local files. Default is `fallback'."
:group 'haskell
:type '(choice (const :tag "Never" never)
(const :tag "As fallback" fallback)
(const :tag "Always" always)))
(defcustom inferior-haskell-web-docs-base
"The base URL of the online libraries documentation. This will
only be used if the value of `inferior-haskell-use-web-docs' is
`always' or `fallback'."
:group 'haskell
:type 'string)
(defcustom haskell-package-manager-name "ghc-pkg"
"Name of the program to consult regarding package details."
:group 'haskell
:type 'string)
(defcustom haskell-package-conf-file
(condition-case nil
(call-process "ghc" nil t nil "--print-libdir")
(expand-file-name "package.conf"
(buffer-substring (point-min) (1- (point-max)))))
;; Don't use `ignore-errors' because this form is not byte-compiled :-(
(error nil))
"Where the package configuration file for the package manager resides.
By default this is set to `ghc --print-libdir`/package.conf."
:group 'haskell
:type 'string)
(defun inferior-haskell-get-module (sym)
"Fetch the module in which SYM is defined."
(let ((info (inferior-haskell-info sym)))
(unless (string-match inferior-haskell-module-re info)
"No documentation information available. Did you forget to C-c C-l?"))
(match-string-no-properties 1 info)))
(defun inferior-haskell-query-ghc-pkg (&rest args)
"Send ARGS to ghc-pkg, or whatever the value of
`haskell-package-manager' is. Insert the output into the current
(apply 'call-process haskell-package-manager-name nil t nil args))
(defun inferior-haskell-get-package-list ()
"Get the list of packages from ghc-pkg, or whatever
`haskell-package-manager-name' is."
(inferior-haskell-query-ghc-pkg "--simple-output" "list")
(split-string (buffer-substring (point-min) (point-max)))))
(defun inferior-haskell-compute-module-alist ()
"Compute a list mapping modules to package names and haddock URLs using ghc-pkg."
(message "Generating module alist...")
(let ((module-alist ()))
(dolist (package (inferior-haskell-get-package-list))
(inferior-haskell-query-ghc-pkg "describe" package)
(let ((package-w/o-version
(replace-regexp-in-string "[-.0-9]*\\'" "" package))
;; Find the Haddock documentation URL for this package
(goto-char (point-min))
(when (re-search-forward "haddock-html:[ \t]+\\(.*[^ \t\n]\\)"
nil t)
(match-string 1)))))
;; Fetch the list of exposed modules for this package
(goto-char (point-min))
(when (re-search-forward "^exposed-modules:\\(.*\\(\n[ \t].*\\)*\\)"
nil t)
(dolist (module (split-string (match-string 1)))
(push (list module package-w/o-version haddock)
(message "Generating module alist... done")
(defcustom inferior-haskell-module-alist-file
;; (expand-file-name "~/.inf-haskell-module-alist")
(expand-file-name (concat "inf-haskell-module-alist-"
(number-to-string (user-uid)))
(if (fboundp 'temp-directory)
"Where to save the module -> package lookup table.
Set this to `nil' to never cache to a file."
:group 'haskell
:type '(choice (const :tag "Don't cache to file" nil) string))
(defvar inferior-haskell-module-alist nil
"Association list of modules to their packages.
Each element is of the form (MODULE PACKAGE HADDOCK), where
MODULE is the name of a module,
PACKAGE is the package it belongs to, and
HADDOCK is the path to that package's Haddock documentation.
This is calculated on-demand using `inferior-haskell-compute-module-alist'.
It's also cached in the file `inferior-haskell-module-alist-file',
so that it can be obtained more quickly next time.")
(defun inferior-haskell-module-alist ()
"Get the module alist from cache or ghc-pkg's info."
;; If we already have computed the alist, use it...
(setq inferior-haskell-module-alist
;; ...otherwise try to read it from the cache file...
(file-readable-p inferior-haskell-module-alist-file)
(file-newer-than-file-p inferior-haskell-module-alist-file
(insert-file-contents inferior-haskell-module-alist-file)
(goto-char (point-min))
(prog1 (read (current-buffer))
(message "Read module alist from file cache."))))
;; ...or generate it again and save it in a file for later.
(let ((alist (inferior-haskell-compute-module-alist)))
(when inferior-haskell-module-alist-file
(print alist (current-buffer))
;; Do the write to a temp file first, then rename it.
;; This makes it more atomic, and suffers from fewer security
;; holes related to race conditions if the file is in /tmp.
(let ((tmp (make-temp-file inferior-haskell-module-alist-file)))
(write-region (point-min) (point-max) tmp)
(rename-file tmp inferior-haskell-module-alist-file
(defvar inferior-haskell-ghc-internal-ident-alist
;; FIXME: Fill this table, ideally semi-automatically.
'(("GHC.Base.return" . "Control.Monad.return")
("GHC.List" . "Data.List")))
(defun inferior-haskell-map-internal-ghc-ident (ident)
"Try to translate some internal GHC identifier to its alter ego in haskell docs."
(let ((head ident)
(tail "")
(while (and (not
(setq remapped
(cdr (assoc head
(string-match "\\.[^.]+\\'" head))
(setq tail (concat (match-string 0 head) tail))
(setq head (substring head 0 (match-beginning 0))))
(concat (or remapped head) tail)))
(defun inferior-haskell-find-haddock (sym)
"Find and open the Haddock documentation of SYM.
Make sure to load the file into GHCi or Hugs first by using C-c C-l.
Only works for functions in a package installed with ghc-pkg, or
whatever the value of `haskell-package-manager-name' is.
This function needs to find which package a given module belongs
to. In order to do this, it computes a module-to-package lookup
alist, which is expensive to compute (it takes upwards of five
seconds with more than about thirty installed packages). As a
result, we cache it across sessions using the cache file
referenced by `inferior-haskell-module-alist-file'. We test to
see if this is newer than `haskell-package-conf-file' every time
we load it."
(let ((sym (haskell-ident-at-point)))
(list (read-string (if (> (length sym) 0)
(format "Find documentation of (default %s): " sym)
"Find documentation of: ")
nil nil sym))))
(setq sym (inferior-haskell-map-internal-ghc-ident sym))
(let* (;; Find the module and look it up in the alist
(module (inferior-haskell-get-module sym))
(alist-record (assoc module (inferior-haskell-module-alist)))
(package (nth 1 alist-record))
(file-name (concat (subst-char-in-string ?. ?- module) ".html"))
(local-path (concat (nth 2 alist-record) "/" file-name))
(url (if (or (eq inferior-haskell-use-web-docs 'always)
(and (not (file-exists-p local-path))
(eq inferior-haskell-use-web-docs 'fallback)))
(concat inferior-haskell-web-docs-base package "/" file-name
;; Jump to the symbol anchor within Haddock.
"#v:" sym)
(and (file-exists-p local-path)
(concat "file://" local-path)))))
(if url (browse-url url) (error "Local file doesn't exist."))))
(provide 'inf-haskell)
;; arch-tag: 61804287-63dd-4052-bc0e-90f691b34b40
;;; inf-haskell.el ends here
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