hsc2hs support

[unhammer]

On doing haskell-process-load-file on a file that ends in .hsc, would it be possible to run hsc2hs on it first and load the resulting .hs (instead of the .hsc)?

[unhammer]

Perhaps something like

(defun haskell--file-name-to-load-string (file-name)
  (format "load \"%s\"" (replace-regexp-in-string
                         "\""
                         "\\\\\""
                         file-name)))

(defun haskell--process-hsc2hs-load ()
  "Run hsc2hs and load the resulting file (unless hsc2hs failed)."
  (let* ((hwin (get-buffer-window (current-buffer)))
         (hs (replace-regexp-in-string "\\.hsc\\'" ".hs" (buffer-file-name)))
         (cbuf (compilation-start (format "hsc2hs %s" (buffer-file-name))
                                  nil
                                  (lambda (_) "*hsc2hs*")))
         (proc (get-buffer-process cbuf)))
    (while (eq (process-status proc) 'run) ; TODO: is there no built-in way to wait on a process?
      (sit-for 0.5))
    (when (equal 0 (process-exit-status proc))
      (select-window (get-buffer-window cbuf))
      (bury-buffer)
      (select-window hwin)
      (haskell-process-file-loadish (haskell--file-name-to-load-string hs)
                                  nil
                                  (current-buffer)))))

;;;###autoload
(defun haskell-process-load-file ()
  "Load the current buffer file."
  (interactive)
  (save-buffer)
  (haskell-interactive-mode-reset-error (haskell-session))
  (if (equal "hsc" (file-name-extension (buffer-file-name)))
      (haskell--process-hsc2hs-load)
    (haskell-process-file-loadish (haskell--file-name-to-load-string (buffer-file-name))
                                  nil
                                  (current-buffer))))

[gracjan]

Hmm, interesting functionality.

Instead of waiting in a loop it would be better to convert the code to callback style. There is a way to trigger a callback when a process has ended, see here set-process-sentinel.

Note that we will need some unit tests before this functionality is accepted. See Writing tests for more details.

[gracjan]

@unhammer, can you turn this into a proper PR? Thanks.

[unhammer]

I actually wanted it to be a blocking wait when I was using hsc2hs, but I suppose if it's a long-running compilation people will want async. I'll make a PR with callbacks, just a sec …

[unhammer]

See #1238 – tests work from my emacs instance, but make check fails with

  (wrong-type-argument stringp
                     ("ghci" "-ferror-spans"))

Full bt:

Test hsc2hs-compile-and-load backtrace:
  shell-quote-argument(("ghci" "-ferror-spans"))
  (list (shell-quote-argument argv))
  (append (quote ("nix-shell" "default.nix" "--command")) (list (shell
  (lambda (argv) (append (quote ("nix-shell" "default.nix" "--command"
  apply((lambda (argv) (append (quote ("nix-shell" "default.nix" "--co
  (append (list (format "Starting inferior GHCi process %s ..." haskel
  (cond ((memql hptype (quote (quote ghci))) (append (list (format "St
  (let ((session-name (haskell-session-name session))) (cond ((memql h
  haskell-process-compute-process-log-and-command(((name . "haskell") 
  (let ((default-directory (haskell-session-cabal-dir session)) (log-a
  (let ((process (or (haskell-session-process session) (haskell-proces
  haskell-process-start(((name . "haskell") (cabal-checksum) (cabal-di
  haskell-session-make("haskell")
  haskell-session-new-assume-from-cabal()
  haskell-session()
  haskell-process-load-file()
  (let ((f (make-temp-file "haskell-hsc2hs-tests.el" nil ".hsc"))) (in
  (progn (switch-to-buffer temp-buffer) (let ((f (make-temp-file "hask
  (unwind-protect (progn (switch-to-buffer temp-buffer) (let ((f (make
  (let ((temp-buffer (generate-new-buffer " *temp*"))) (unwind-protect
  (closure (t) nil (let ((temp-buffer (generate-new-buffer " *temp*"))
  #[0 "\306\307!r\211q\210\310\311\312\313\314\315!\316\"\317\320%DC
  funcall(#[0 "\306\307!r\211q\210\310\311\312\313\314\315!\316\"\31
  ert--run-test-internal([cl-struct-ert--test-execution-info [cl-struc
  #[0 "r\304 q\210\305 )\306\307\310\311\312\313!\314\"\315\316%DC\2
  funcall(#[0 "r\304 q\210\305 )\306\307\310\311\312\313!\314\"\315\
  ert-run-test([cl-struct-ert-test hsc2hs-compile-and-load nil (closur
  ert-run-or-rerun-test([cl-struct-ert--stats t [[cl-struct-ert-test b
  ert-run-tests(t #[385 "\306\307\"\203D\211\211G\310U\203\211@\20
  ert-run-tests-batch(nil)
  ert-run-tests-batch-and-exit()
  command-line-1(("--eval" "(add-to-list 'load-path (expand-file-name 
  command-line()
  normal-top-level()
Test hsc2hs-compile-and-load condition:
    (wrong-type-argument stringp
                         ("ghci" "-ferror-spans"))
   FAILED  401/427  hsc2hs-compile-and-load

[gracjan]

Closing due to low interest.