Re: [PATCH] ob-haskell: Line Continuations Mangle Block Output

[Nick Daly <nick.m.daly@gmail.com>]

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Apologies, one last patch.

On Sat, May 23, 2020 at 7:02 PM Nick Daly <nick.m.daly@gmail.com> wrote:
> : "^\\*?[[:upper:]][\\._[:alnum:]]*\\(?:
> \\*?[[:upper:]][\\._[:alnum:]]*\\)*\\( λ\\)?> "
>
> =comint-prompt-regexp='s variable documentation calls out much simpler
> regexps
>
> : "^[^>]+\\(> \\)?"

This simplified patch breaks one case that I'd forgotten about: the
true one-liner, where the output displays before the "Prelude> "
prompt even appears.

#+BEGIN_SRC haskell
scanl (+) 0 [1,2,3,4]
#+END_SRC

#+BEGIN_EXAMPLE
Prelude> scanl (+) 0 [1,2,3,4]
"org-babel-haskell-eoe"
[0,1,3,6,10]
Prelude> "org-babel-haskell-eoe"
Prelude>
#+END_EXAMPLE

This latest patch updates the original (more complicated) regexp that
works with this out-of-order output.  This should display the expected
result in all known cases:

One liners:

#+BEGIN_SRC haskell
scanl (+) 0 [1,2,3,4]
#+END_SRC

#+RESULTS:
| 0 | 1 | 3 | 6 | 10 |

Silent multi-line blocks:

#+BEGIN_SRC haskell :results silent
:{
flip' :: (a -> b -> c) -> (b -> a -> c)
flip' f = \x y -> f y x
:}
#+END_SRC

Multi-line blocks with value results:

#+BEGIN_SRC haskell
:{
sum' :: (Num a) => [a] -> a
sum' xs = foldl (\ acc x -> acc + x) 0 xs
:}
sum' [1,2,3,4] == 10
#+END_SRC

#+RESULTS:
: True

Multi-line blocks with output results:

#+BEGIN_SRC haskell :results output
:{
sum' :: (Num a) => [a] -> a
sum' xs = foldl (\ acc x -> acc + x) 0 xs
:}
print "hi"
#+END_SRC

#+RESULTS:
:
: hi

Thanks again for your time,
Nick

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diff --git a/lisp/ob-haskell.el b/lisp/ob-haskell.el
index bea162528..6ac34f2f5 100644
--- a/lisp/ob-haskell.el
+++ b/lisp/ob-haskell.el
@@ -56,15 +56,27 @@
 
 (defvar org-babel-haskell-eoe "\"org-babel-haskell-eoe\"")
 
-(defvar haskell-prompt-regexp)
+(defvar haskell-prompt-regexp "^\\(\\*?[[:upper:]][\\._[:alnum:]]*\\(?: \\*?[[:upper:]][\\._[:alnum:]]*\\)*\\( λ\\)?[|>] \\)*"
+  "Filter out prompts from Haskell interpreters:
+
+GHC:
+
+- 'output
+   ^Prelude> EOE'
+- '^Prelude> output EOE'
+- '^Prelude| Prelude| Prelude> output EOE'
+
+Unknown Interpreter:
+
+- '^> '
+- '^λ> '")
 
 (defun org-babel-execute:haskell (body params)
   "Execute a block of Haskell code."
   (require 'inf-haskell)
   (add-hook 'inferior-haskell-hook
             (lambda ()
-              (setq-local comint-prompt-regexp
-                          (concat haskell-prompt-regexp "\\|^λ?> "))))
+              (setq-local comint-prompt-regexp haskell-prompt-regexp)))
   (let* ((session (cdr (assq :session params)))
          (result-type (cdr (assq :result-type params)))
          (full-body (org-babel-expand-body:generic