Revert "Inferior-haskell: do not insert repeated prompts."

This reverts commit e826b2f.

See #1806 and #1867

Author: purcell

inf-haskell.el

@@ -113,25 +113,6 @@ The format should be the same as for `compilation-error-regexp-alist'.")
 correctly interpret multi-line input even when modules are
 imported.")
 
-(defconst inferior-haskell-cont-prompt-regexp
-  "^[[:alnum:].*_() |λ]*| "
-  "Continuation prompt rexep.
-Used to remove them from the output by the comint preoutput filter.  See
-`inferior-haskell-remove-extra-prompts'.
-
-This should be a similar regexp as `haskell-prompt-regexp', but it usually
-ends with \"| \" instead of \"> \".")
-
-(defconst inferior-haskell-maybe-cont-prompt-regexp
-  "^[[:alnum:].*_() |λ]*[>|] "
-  "A continuation or non-continuation prompt regexp.
-This should match any prompt, a continuation or a common prompt.  This regexp
-should be similar to `haskell-prompt-regexp' and
-`inferior-haskell-cont-prompt-regex' as it should match both.
-
-It is used to remove multiple prompts on the comint preoutput filter.  See
-`inferior-haskell-remove-extra-prompts'.")
-
 ;;; TODO
 ;;; -> Make font lock work for strings, directories, hyperlinks
 ;;; -> Make font lock work for key words???
@@ -180,40 +161,7 @@ It is used to remove multiple prompts on the comint preoutput filter.  See
         (define-key map keys (lookup-key compilation-minor-mode-map keys)))
       (add-to-list 'minor-mode-overriding-map-alist
                    (cons 'compilation-minor-mode map))))
-  (add-hook 'inferior-haskell-hook 'inferior-haskell-init)
-  
-  ;; Avoid multiple prompts at the end of the output
-  (add-hook 'comint-preoutput-filter-functions
-            #'inferior-haskell-remove-extra-prompts nil t))
-
-(defun inferior-haskell-remove-extra-prompts (str)
-  "Remove any extra Haskell-prompts from STR.
-Remove multiple prompts from STR.  All prompts indicating continuation are
-completely removed.  Only remain the last non-continuantion prompt.
-
-Examples:
-The input \"Prelude> Prelude> \" will return \"Prelude> \".
-The input \"Prelude| Prelude| \" will return \"\".
-
-These kind of output are usually produced by the multiple line input (i.e. when
-using \":{ ... :}\" code in the GHCi interpreter).  Sometimes, comint would note
-filter the prompts out.  For this reason, this function shoud be added to the
-hook `comint-preoutput-filter-functions', to be executed before comint insert
-STR to the buffer.
-
-Some libraries, such as ob-haskell.el, considers the multilple prompts as part
-of the evaluation output.  Moreover, it does not provide any information to the
-user. Removing these prompts provides a better reading and less code for parsing
-the output."
-  (let ((last-match nil))
-    (while (string-match inferior-haskell-maybe-cont-prompt-regexp str)
-      (setq last-match (match-string 0 str))
-      (setq str (substring str (match-end 0))))
-    ;; Remove prompt-cont if it is the last one.
-    (if (or (null last-match)
-            (string-match inferior-haskell-cont-prompt-regexp last-match))
-        str
-      (concat last-match str))))
+  (add-hook 'inferior-haskell-hook 'inferior-haskell-init))
 
 (defvar inferior-haskell-buffer nil
   "The buffer in which the inferior process is running.")