Re: Unhealthy Haskell babel

[Lawrence Bottorff <borgauf@gmail.com>]

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Yes -- and I think I came across this long ago during another attempt and
totally forgot about it. I think I'll write this up on emacs.stackexchange
so others will not have to scrounge around. I'm pursuing this because I
really believe emacs org-mode "reproducible research" is superior to all
other methods so far.

On Thu, Dec 10, 2020 at 12:40 PM Immanuel Litzroth <
immanuel.litzroth@gmail.com> wrote:

> Well another possible solution is to wrap the code blocks in
> :{
> xxx
> :}
> in
> (defun org-babel-execute:haskell (body params) -- ob-haskell.el
> Immanuel
>
> On Thu, Dec 10, 2020 at 6:21 PM Lawrence Bottorff <borgauf@gmail.com>
> wrote:
> >
> > I see your point, i.e., compiled, multi-file projects are not really
> meant for the REPL-dominant world of org-mode babel. Babel's sweet-spot
> would be the interpreted world, the very best probably a Lisp language.
> Still, the ability to add code to a running REPL should be possible. As I
> mentioned, SML is a sibling of Haskell and its babel implementation worked
> fine for me as I worked through an SML course. So yes, this appears to be a
> Haskell REPL issue. I'm just a beginner with Haskell, and all my intro
> texts start you out using the ghci REPL interactively. But then they switch
> you over to a text file compiled in the REPL with :l myfile.hs . . . no
> explanation as to why you can't just continue with the REPL putting the
> program in line-by-line. The fact that I can use the :set +m to include
> multiple lines of code, but cannot do a type definition is rather bizarre,
> though. This is a decision Haskell made with their REPL and babel really
> can't do much about it, I suppose. The Haskell .lhs literate option is
> interesting. Yes, I'd like to see your tangle option, please.
> >
> > On Thu, Dec 10, 2020 at 4:28 AM Immanuel Litzroth <
> immanuel.litzroth@gmail.com> wrote:
> >>
> >> I don't think org-babel is a good fit for compiled languages. If the
> >> idea is to just take 1 snippet,
> >> and "execute" that it means that to have a consistent whole you'd need
> >> to put all the modules of
> >> your program into that snippet (already impossible in Haskell, you can
> >> have only 1 module per file),
> >> compile that, run the resulting binary. Or org mode would have to have
> >> some idea of what needs to
> >> be retangled & rebuilt.
> >> I think that using org-babel for compiled, multifile languages will
> >> only work in very simple cases -- and
> >> even then.. -- but will lead to problems very soon.
> >> Immanuel
> >>
> >> On Thu, Dec 10, 2020 at 4:21 AM Lawrence Bottorff <borgauf@gmail.com>
> wrote:
> >> >
> >> > I'm looking into Haskell (latest ghci) again on org-mode. This
> >> >
> >> > #+begin_src haskell :results verbatim :exports both
> >> > :set +m
> >> > doubleSmallNumber x = if x > 100
> >> >   then x
> >> >   else x*2
> >> > #+end_src
> >> >
> >> > works, but still the :set +m is necessary for it to see the whole.
> But this
> >> >
> >> > #+begin_src haskell :results verbatim :exports both
> >> > :set +m
> >> > factorial :: Int -> Int
> >> > factorial 0 = 1
> >> > factorial n = n * factorial (n - 1)
> >> > #+end_src
> >> >
> >> > results in this on the REPL side:
> >> >
> >> > Prelude> :set +m
> >> > factorial :: Int -> Int
> >> > factorial 0 = 1
> >> > factorial n = n * factorial (n - 1)
> >> > "org-babel-haskell-eoe"
> >> > Prelude>
> >> > <interactive>:26:1-23: error:
> >> >     • No instance for (Show (Int -> Int)) arising from a use of
> ‘print’
> >> >         (maybe you haven't applied a function to enough arguments?)
> >> >     • In a stmt of an interactive GHCi command: print it
> >> > Prelude> Prelude> Prelude> "org-babel-haskell-eoe"
> >> >
> >> > which is the same behavior if I try to feed the program into the REPL
> one line at a time, i.e.,
> >> >
> >> > Prelude> factorial :: Int -> Int
> >> >
> >> > <interactive>:40:1-23: error:
> >> >     • No instance for (Show (Int -> Int)) arising from a use of
> ‘print’
> >> >         (maybe you haven't applied a function to enough arguments?)
> >> >     • In a stmt of an interactive GHCi command: print it
> >> >
> >> > So the :set +m trick (take multiple lines) doesn't help here.
> Obviously, Haskell is not ready to be used with Babel. Can it be fixed?
> BTW, this does work with the regular ghci REPL and haskell-mode. If it
> helps, Standard ML, which has very similar syntax (it was Haskell's
> parent), works fine.
> >> >
> >> > LB
> >>
> >>
> >>
> >> --
> >> -- Researching the dual problem of finding the function that has a
> >> given point as fixpoint.
>
>
>
> --
> -- Researching the dual problem of finding the function that has a
> given point as fixpoint.
>

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