Nick Daly writes:
> After a bit of tinkering, I realized there are two things going on
> here, only one of which I fully understand:
>
> 1. My core functional issue is that =comint-prompt-regexp= isn't set
> up to handle the "Prelude| " entries or the repeated prompts. The
> other patches I submitted were unnecessary.
>
> 2. The =comint-prompt-regexp= gets default values from somewhere I
> don't understand and can't find with a quick source grep.
Here's what I can gather. inf-haskell used to set comint-prompt-regexp
in the body of inferior-haskell-mode. Here's an example from 11d6abf
(2017-08-24):
(setq-local comint-prompt-regexp
;; Why the backslash in [\\._[:alnum:]]?
"^\\*?[[:upper:]][\\._[:alnum:]]*\\(?:
\\*?[[:upper:]][\\._[:alnum:]]*\\)*\\( λ\\)?> \\|^λ?> $")
In ca94d81 (revamped inf-haskell, 2017-08-26), which was included in the
v17.1 release, haskell-prompt-regexp was introduced and the line above
is now
(setq-local comint-prompt-regexp haskell-prompt-regexp)
> In ob-haskell, we set =comint-prompt-regexp= to the (undefined)
> haskell-prompt plus "or optional-lambda":
With a haskell-mode after the commit I point to above, it shouldn't be
undefined at the time we set comint-prompt-regexp because
org-babel-interpret-haskell loads inf-haskell before that.
However, I'm confused why Org's b46787743 (Fix ob-haskell.el to work
with custom ghci prompts, 2017-12-02) added the λ bit (author of that
patch cc'd). As far as I can tell, that is a part of
inferior-haskell-mode's default comint-prompt-regexp and has been since
28997b2 (Add support for popular "λ> " prompt to inf-haskell,
2013-07-04).
You've sent an updated patch in a follow-up message, so I'll continue
there...
