Enhance haskell-version to show more information

This commit marks `haskell-version` autoloaded and `M-x
haskell-version` now echos more information, e.g.

 "haskell-mode version 2.9.1 (2.9.1-93-gb76e104-dirty @ /home/hvr/.emacs.d/elisp/haskell-mode/)"

This style has been copied from Org mode's `org-version`.

Author: hvr

Makefile

@@ -1,4 +1,6 @@
-VERSION = $(shell git describe --tags --dirty | sed 's/_/\./g')
+VERSION = $(shell git describe --tags --abbrev=0 | sed 's/_/\./g')
+GIT_VERSION = $(shell git describe --tags --dirty | sed 's/_/\./g')
+
 EMACS = emacs
 EFLAGS =
 BATCH = $(EMACS) $(EFLAGS) --batch -Q -L .
@@ -35,7 +37,7 @@ ELCFILES = $(ELFILES:.el=.elc)
 AUTOLOADS = haskell-site-file.el
 DIST_FILES = $(ELFILES) $(ELCFILES) $(AUTOLOADS) logo.svg Makefile README.md NEWS
 DIST_FILES_EX = examples/init.el examples/fontlock.hs examples/indent.hs
-TGZ = haskell-mode-$(VERSION).tar.gz
+TGZ = haskell-mode-$(GIT_VERSION).tar.gz
 
 %.elc: %.el
 	@$(BATCH) -f batch-byte-compile $<
@@ -59,21 +61,22 @@ $(AUTOLOADS): $(ELFILES) haskell-mode.elc
 
 # embed version number into .elc file
 haskell-mode.elc: haskell-mode.el
-	sed -e 's/\$$Name:  \$$/$(VERSION)/g' < haskell-mode.el > haskell-mode.tmp.el #NO_DIST
+	sed -e 's/@GIT_VERSION@/$(GIT_VERSION)/g;s/@VERSION@/$(VERSION)/g' < haskell-mode.el > haskell-mode.tmp.el #NO_DIST
 	@$(BATCH) -f batch-byte-compile haskell-mode.tmp.el #NO_DIST
 	mv haskell-mode.tmp.elc haskell-mode.elc #NO_DIST
 	$(RM) haskell-mode.tmp.el #NO_DIST
 
 $(TGZ): $(DIST_FILES)
-	rm -rf haskell-mode-$(VERSION)
-	mkdir haskell-mode-$(VERSION)
-	cp -p $(DIST_FILES) haskell-mode-$(VERSION)
-	mkdir haskell-mode-$(VERSION)/examples
-	cp -p $(DIST_FILES_EX) haskell-mode-$(VERSION)/examples
+	rm -rf haskell-mode-$(GIT_VERSION)
+	mkdir haskell-mode-$(GIT_VERSION)
+	cp -p $(DIST_FILES) haskell-mode-$(GIT_VERSION)
+	mkdir haskell-mode-$(GIT_VERSION)/examples
+	cp -p $(DIST_FILES_EX) haskell-mode-$(GIT_VERSION)/examples
 
-	printf "1s/=.*/= $(VERSION)/\nw\n" | ed -s haskell-mode-$(VERSION)/Makefile #NO_DIST
-	printf "g/NO_DIST/d\nw\n" | ed -s haskell-mode-$(VERSION)/Makefile #NO_DIST
-	printf ',s/\$$Name:  \$$/$(VERSION)/\nw\n' | ed -s haskell-mode-$(VERSION)/haskell-mode.el #NO_DIST
+	printf "1s/=.*/= $(VERSION)/\nw\n" | ed -s haskell-mode-$(GIT_VERSION)/Makefile #NO_DIST
+	printf "2s/=.*/= $(GIT_VERSION)/\nw\n" | ed -s haskell-mode-$(GIT_VERSION)/Makefile #NO_DIST
+	printf "g/NO_DIST/d\nw\n" | ed -s haskell-mode-$(GIT_VERSION)/Makefile #NO_DIST
+	printf ',s/@VERSION@/$(VERSION)/\nw\n' | ed -s haskell-mode-$(GIT_VERSION)/haskell-mode.el #NO_DIST
 
-	tar cvzf $(TGZ) haskell-mode-$(VERSION)
-	rm -rf haskell-mode-$(VERSION)
+	tar cvzf $(TGZ) haskell-mode-$(GIT_VERSION)
+	rm -rf haskell-mode-$(GIT_VERSION)

haskell-mode.el

@@ -9,7 +9,6 @@
 ;;          2001-2002 Reuben Thomas (>=v1.4)
 ;;          2003      Dave Love <[email protected]>
 ;; Keywords: faces files Haskell
-;; Version: $Name:  $
 ;; URL: https://github.com/haskell/haskell-mode
 
 ;; This file is not part of GNU Emacs.
@@ -151,12 +150,28 @@
 ;; All functions/variables start with `(literate-)haskell-'.
 
 ;; Version of mode.
-(defconst haskell-version "$Name:  $"
-  "`haskell-mode' version number.")
-(defun haskell-version ()
-  "Echo the current version of `haskell-mode' in the minibuffer."
-  (interactive)
-  (message "Using haskell-mode version %s" haskell-version))
+(defconst haskell-version "@VERSION@"
+  "The release version of `haskell-mode'.")
+
+(defconst haskell-git-version "@GIT_VERSION@"
+  "The Git version of org-mode `haskell-mode'.")
+
+;;;###autoload
+(defun haskell-version (&optional here)
+  "Show the `haskell-mode` version in the echo area.
+With prefix argument HERE, insert it at point.
+When FULL is non-nil, use a verbose version string.
+When MESSAGE is non-nil, display a message with the version."
+  (interactive "P")
+  (let* ((haskell-mode-dir (ignore-errors
+                             (file-name-directory (or (locate-library "haskell-mode") ""))))
+         (_version (format "haskell-mode version %s (%s @ %s)"
+                            haskell-version
+                            haskell-git-version
+                            haskell-mode-dir)))
+    (if here
+        (insert _version)
+      (message "%s" _version))))
 
 (defgroup haskell nil
   "Major mode for editing Haskell programs."