[nongnu] elpa/haskell-tng-mode c2a5b64 005/385: cleaner import fontification

[ELPA Syncer]

branch: elpa/haskell-tng-mode
commit c2a5b641b95268542a77e2771c4b49659565b08b
Author: Tseen She <ts33n.sh3@gmail.com>
Commit: Tseen She <ts33n.sh3@gmail.com>

    cleaner import fontification
---
 README.md                | 10 ++++------
 haskell-tng-font-lock.el | 43 ++++++++++++++++++++++++++-----------------
 haskell-tng-mode.el      |  7 +++++--
 3 files changed, 35 insertions(+), 25 deletions(-)

diff --git a/README.md b/README.md
index ad3fc08..b9e636e 100644
--- a/README.md
+++ b/README.md
@@ -1,14 +1,12 @@
 # Haskell Mode: The Next Generation
 
-This is an exploratory alternative to 
[`haskell-mode`](https://github.com/haskell/haskell-mode/) that answers the 
question
-
-> How would we support Haskell in GNU Emacs if we started today?
+This is an exploratory alternative to 
[`haskell-mode`](https://github.com/haskell/haskell-mode/) that answers the 
question *how would we support Haskell in GNU Emacs if we started today?*
 
 ## Why?
 
-`haskell-mode` is almost 30 years old and has accumulated more than 25,000 
lines of code. Nobody wants to maintain that.
+`haskell-mode` is almost 30 years old and has accumulated more than 25,000 
lines of code. It's too much to handle.
 
-The GNU Emacs ecosystem has evolved to provide many features that 
`haskell-mode` independently implemented, such as 
[`projectile`](https://github.com/bbatsov/projectile), 
[`comint-mode`](https://masteringemacs.org/article/comint-writing-command-interpreter),
 [`highlight-symbol`](https://melpa.org/##/highlight-symbol), 
[`company-mode`](http://company-mode.github.io), 
[`yasnippet`](http://joaotavora.github.io/yasnippet/), 
[`polymode`](https://github.com/polymode/polymode), [`smartparens`]( [...]
+Meanwhile, the GNU Emacs ecosystem has evolved to provide many features that 
`haskell-mode` independently implemented, such as 
[`projectile`](https://github.com/bbatsov/projectile), 
[`comint-mode`](https://masteringemacs.org/article/comint-writing-command-interpreter),
 [`highlight-symbol`](https://melpa.org/##/highlight-symbol), 
[`pretty-symbols`](https://github.com/drothlis/pretty-symbols), 
[`company-mode`](http://company-mode.github.io), 
[`yasnippet`](http://joaotavora.github.io/yasnip [...]
 
 ## Approach
 
@@ -54,7 +52,7 @@ This is the status of core features:
   - [ ] `yasnippet` templates
   - [ ] `smartparens` compatibility (or something from stdlib)
   - [ ] `LANGUAGE` management
-  - [ ] `import` management
+  - [ ] `import` management (via hoogle and 
[`hsimport`](https://hackage.haskell.org/package/hsimport))
 - Compiling:
   - [ ] `haskell-compile` for build tool agnostic interaction with `ghc`
   - [ ] `comint-mode` based `ghc` repl
diff --git a/haskell-tng-font-lock.el b/haskell-tng-font-lock.el
index a357192..7be03a2 100644
--- a/haskell-tng-font-lock.el
+++ b/haskell-tng-font-lock.el
@@ -14,6 +14,12 @@
 ;;  parsing, but until that day, we do it the idiomatic Emacs way (with hacks
 ;;  and more hacks).
 ;;
+;;  We try very hard to use only single line fontifications, since multiline
+;;  introduces both a performance and maintenance penalty. For this reason, 
some
+;;  very unusual styles of Haskell, although valid, may not be supported. For
+;;  example, comments in unusual positions and line breaks after contextual
+;;  markers (e.g. multiline imports may pick up incorrect colours).
+;;
 ;;  
https://www.gnu.org/software/emacs/manual/html_mono/elisp.html#Font-Lock-Mode
 ;;
 ;;; Code:
@@ -47,17 +53,17 @@
 ;; TODO: pragmas
 ;;
 ;; TODO: numeric / char primitives?
-
-;; FIXME: consider using rx instead of regexes... there are a lot of escapes
-;; that obfuscate the meaning, plus we could use DRY.
+;;
+;; TODO: haddock
 
 (setq
  haskell-tng:keywords
  ;; These regexps use the `rx' library so we can reuse common subpatterns. It
  ;; also increases the readability of the code and, in many cases, allows us to
  ;; do more work in a single regexp instead of multiple passes.
- (let ((conid '(: upper (* wordchar)))
-       (consym '(: ":" (+ (syntax symbol)))))
+ (let* ((conid '(: upper (* wordchar)))
+        (qual `(: (+ (: ,conid (char ?.)))))
+        (consym '(: ":" (+ (syntax symbol)))))
    `(;; reservedid / reservedop
      (,(rx-to-string
         '(|
@@ -73,20 +79,23 @@
           (: symbol-start (char ?\\))))
       . 'haskell-tng:keyword)
 
-     ;; TODO: anchored matchers
-     ;; TODO: contextual / multiline support for the import region.
-     ;; qualified/hiding/as are keywords when used in imports
-     ("\\_<import\\_>[[:space:]]+\\_<\\(qualified\\)\\_>" 1 
'haskell-tng:keyword)
-     ("\\_<import\\_>[^(]+?\\_<\\(hiding\\|as\\)\\_>" 1 'haskell-tng:keyword)
-     
("\\_<import\\_>\\(?:[[:space:]]\\|qualified\\)+\\_<\\([[:upper:]]\\(?:\\.\\|\\w\\)*\\)\\_>"
-      1 'haskell-tng:module)
-     ("\\_<import\\_>[^(]+?\\_<as[[:space:]]+\\([[:upper:]]\\w+\\)"
+     ;; modules
+     (,(rx-to-string `(: symbol-start "module" symbol-end (+ space)
+                         symbol-start (group (opt ,qual) ,conid) symbol-end))
       1 'haskell-tng:module)
 
-     ;; introducing modules
-     (,(rx-to-string '(: symbol-start "module" symbol-end (+ space)
-                         symbol-start (group upper (* wordchar)) symbol-end))
-      1 'haskell-tng:module)
+     ;; imports
+     (,(rx-to-string '(: word-start "import" word-end)) ;; anchor matcher
+      (,(rx-to-string `(: point (+ space) (group word-start "qualified" 
word-end)))
+       nil nil (1 'haskell-tng:keyword))
+      (,(rx-to-string `(: point
+                          (opt (+ space) word-start "qualified" word-end)
+                          (+ space) word-start (group (opt ,qual) ,conid) 
word-end))
+       nil nil (1 'haskell-tng:module))
+      (,(rx-to-string `(: point (+? (not (any ?\()))
+                          word-start (group (| "hiding" "as")) word-end
+                          (opt (+ space) word-start (group ,conid) word-end)))
+       nil nil (1 'haskell-tng:keyword) (2 'haskell-tng:module nil t)))
 
      ;; uses of F.Q.N.s
      (,(rx-to-string `(: symbol-start (+ (: ,conid "."))))
diff --git a/haskell-tng-mode.el b/haskell-tng-mode.el
index 4cd0798..1887637 100644
--- a/haskell-tng-mode.el
+++ b/haskell-tng-mode.el
@@ -27,9 +27,12 @@
   ;; TODO paragraph-start, paragraph-separate, fill-paragraph-function
   ;;
   ;; TODO comment-start, comment-padding, comment-start-skip, comment-end,
-  ;;      comment-end-skip, comment-auto-fill-only-comments, 
parse-sexp-ignore-comments
+  ;;      comment-end-skip, comment-auto-fill-only-comments,
+  ;;      parse-sexp-ignore-comments (it is annoying that we must specify
+  ;;      comments here AND in the syntax table)
   ;;
-  ;; (it is annoying that we specify comments here AND in the syntax table)
+  ;; TODO mark-defun
+  ;; TODO font-lock-mark-block-function
 
   (setq
    ;; TAB is evil