Org Haskell code blocks

Org Haskell code blocks

[Dominik Schrempf]

Hello,

I have trouble using Haskell code blocks in Org Mode.

1. I need to use the following Org Mode file header:

#+property: :header-args:haskell: :prologue ":{\n" :epilogue ":}\n"

#+begin_src haskell :exports none :results none
:set prompt-cont ""
#+end_src

Otherwise, the results of Haskell code blocks are scrambled.

2. I need to set `haskell-process-type' to `ghci'. The default
interpreter `cabal-repl' does not find any external modules (even core
modules included with GHC).

However, I get the error message "org-babel-script-escape:
‘org-babel-script-escape’ expects a string", when executing the first
code block which starts the interpreter. Seemingly, the error has no
effect because everything works fine.

3. I have to set `org-edit-src-content-indentation` to 0, and always put
the source code to text column 0, otherwise syntax highlighting does not
work.

Do others have the same problems? If so, have there been discussions
about how to improve this situation?

Thank you for your help!

Dominik

Re: Org Haskell code blocks

[Dominik Schrempf]

I apologize, the settings described in Point 1 actually have no effect.
Multi line input works out of the box (at least with "ghci" as
described). However, the result output is still scrambled (e.g., empty
lines, unnecessary "ghci>" prompts in results)

Dominik

Dominik Schrempf <dominik.schrempf@gmail.com> writes:

> Hello,
>
> I have trouble using Haskell code blocks in Org Mode.
>
> 1. I need to use the following Org Mode file header:
>
> #+property: :header-args:haskell: :prologue ":{\n" :epilogue ":}\n"
>
> #+begin_src haskell :exports none :results none
> :set prompt-cont ""
> #+end_src
>
> Otherwise, the results of Haskell code blocks are scrambled.
>
> 2. I need to set `haskell-process-type' to `ghci'. The default
> interpreter `cabal-repl' does not find any external modules (even core
> modules included with GHC).
>
> However, I get the error message "org-babel-script-escape:
> ‘org-babel-script-escape’ expects a string", when executing the first
> code block which starts the interpreter. Seemingly, the error has no
> effect because everything works fine.
>
> 3. I have to set `org-edit-src-content-indentation` to 0, and always put
> the source code to text column 0, otherwise syntax highlighting does not
> work.
>
> Do others have the same problems? If so, have there been discussions
> about how to improve this situation?
>
> Thank you for your help!
>
> Dominik

Re: Org Haskell code blocks

[Bruno Barbier]

Hi,

Dominik Schrempf <dominik.schrempf@gmail.com> writes:

> ...
> However, the result output is still scrambled (e.g., empty
> lines, unnecessary "ghci>" prompts in results)
>

For me, ghci is selected by default.

Here is the config I've used to test it:

  | emacs-version           |            28.1 |
  | org-version             |           9.5.2 |
  | haskell-process-type    |            auto |
  | org-babel-script-escape | <not available> |


Here is my simple test:
  #+begin_src haskell
    1+2
  #+end_src

  #+RESULTS:
  : 3

The variable 'org-babel-script-escape' doesn't exist in the version that
I'm using. And, the prompt is not "ghci>" but the current module name.

Which version of org are you using ? Could you try with a recent version
and provide a minimal complete example using a minimal configuration ?
(see the org mode manual (info "(org)Feedback")).

Thanks,


Bruno

Re: Org Haskell code blocks

[Dominik Schrempf]

Hi Bruno,

glad to hear that it works for you.


Ad 'org-babel-script-escape': I use Org version 9.6. I do not temper
with 'org-babel-script-escape', it is used by the respective babel
modules --- 'ob-haskell' in this case. The error also occurs with
'cabal-repl' as process type.


Ad 'haskell-process-type': When I use 'haskell-process-type' 'auto', it
chooses 'cabal-repl' which will also fire up 'ghci' but the setup is
faulty, because it does not find any modules, as I described. I just
checked and this is not a fault of org-mode. The command 'cabal repl'
also fails to access any modules when executed in the terminal. I think
it requires a `.cabal` file, which I usually do not have when using an
Org file. I quote the help text from 'cabal repl':

    Open an interactive session for a component within the project.

I think this is not the correct default for Org mode, because usually
there is no "project", but just an Org file.

If I use 'haskell-process-type' 'ghci', all modules I have installed
along with GHC are found, as I expect them to be.


Ad scrambling: The scrambling happens with multi-line input. For example

    #+begin_src haskell :exports both :results output
    let x = 10
    let y = 12
    x*y
    [x,y]
    #+end_src

    #+results:
    :
    : ghci> 120
    : [10,12]

Do you get syntax highlighting when the source code is indented (for
example in list items).

Thanks for your reply!

Dominik

Bruno Barbier <brubar.cs@gmail.com> writes:

> Hi,
>
> Dominik Schrempf <dominik.schrempf@gmail.com> writes:
>
>> ...
>> However, the result output is still scrambled (e.g., empty
>> lines, unnecessary "ghci>" prompts in results)
>>
>
> For me, ghci is selected by default.
>
> Here is the config I've used to test it:
>
>   | emacs-version           |            28.1 |
>   | org-version             |           9.5.2 |
>   | haskell-process-type    |            auto |
>   | org-babel-script-escape | <not available> |
>
>
> Here is my simple test:
>
>   #+begin_src haskell
>     1+2
>   #+end_src
>
>   #+RESULTS:
>   : 3
>
> The variable 'org-babel-script-escape' doesn't exist in the version that
> I'm using. And, the prompt is not "ghci>" but the current module name.
>
> Which version of org are you using ? Could you try with a recent version
> and provide a minimal complete example using a minimal configuration ?
> (see the org mode manual (info "(org)Feedback")).
>
> Thanks,
>
>
> Bruno

Re: Org Haskell code blocks

[Ihor Radchenko]

Dominik Schrempf <dominik.schrempf@gmail.com> writes:

> Ad scrambling: The scrambling happens with multi-line input. For example
>
>     #+begin_src haskell :exports both :results output
>     let x = 10
>     let y = 12
>     x*y
>     [x,y]
>     #+end_src
>
>     #+results:
>     :
>     : ghci> 120
>     : [10,12]

I am unable to reproduce on the latest main.
Likely because of recent fixes in ob-comint.

> Do you get syntax highlighting when the source code is indented (for
> example in list items).

I have the above code fontified.
Could you please provide an example of the code that is not being fontified?

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>

Re: Org Haskell code blocks

[Dominik Schrempf]

Dear Ihor,

thank you, these are great news!

Syntax highlighting is not working, for example, with the following
snippet and code block:

begin_snippet

- An example of a function:

  #+begin_src haskell :exports code :results none
  f :: a -> b
  #+end_src

end_snippet

Note the indentation. The code block is indented by 2 spaces, because it
belongs to the list item above. The indentation makes the syntax
highlighting fail. It may well be that this is non-standard usage of
code blocks, but it is very convenient to preserve indentation in this
way.

I also fixed the detection of 'haskell-process-type'. It turns out, I
had some local configuration preferring 'cabal-repl', even without the
required project files. 'haskell-process-type' 'auto' works correctly, I
apologize.

Thank you for your help!

Dominik

Ihor Radchenko <yantar92@posteo.net> writes:

> Dominik Schrempf <dominik.schrempf@gmail.com> writes:
>
>> Ad scrambling: The scrambling happens with multi-line input. For example
>>
>>     #+begin_src haskell :exports both :results output
>>     let x = 10
>>     let y = 12
>>     x*y
>>     [x,y]
>>     #+end_src
>>
>>     #+results:
>>     :
>>     : ghci> 120
>>     : [10,12]
>
> I am unable to reproduce on the latest main.
> Likely because of recent fixes in ob-comint.
>
>> Do you get syntax highlighting when the source code is indented (for
>> example in list items).
>
> I have the above code fontified.
> Could you please provide an example of the code that is not being fontified?

Re: Org Haskell code blocks

[Ihor Radchenko]

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Dominik Schrempf <dominik.schrempf@gmail.com> writes:

> Syntax highlighting is not working, for example, with the following
> snippet and code block:
>
> begin_snippet
>
> - An example of a function:
>
>   #+begin_src haskell :exports code :results none
>   f :: a -> b
>   #+end_src
>
> end_snippet

Works on my side (I think).
See the attached screenshot.
I am on the latest main.


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-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>

Re: Org Haskell code blocks

[Dominik Schrempf]

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Ihor Radchenko <yantar92@posteo.net> writes:

> Dominik Schrempf <dominik.schrempf@gmail.com> writes:
>
>> Syntax highlighting is not working, for example, with the following
>> snippet and code block:
>>
>> begin_snippet
>>
>> - An example of a function:
>>
>>   #+begin_src haskell :exports code :results none
>>   f :: a -> b
>>   #+end_src
>>
>> end_snippet
>
> Works on my side (I think).
> See the attached screenshot.
> I am on the latest main.
>
> [2. image/png; haskell-fontification.png]...

This is interesting. For me, syntax highlighting works partially. For
example, keywords are highlighted, but function names are not. See below.


[-- Attachment #2: SyntaxHighlightingHaskell.png --]
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Re: Org Haskell code blocks

[Ihor Radchenko]

Dominik Schrempf <dominik.schrempf@gmail.com> writes:

> This is interesting. For me, syntax highlighting works partially. For
> example, keywords are highlighted, but function names are not. See below.

I confirm the issue with your example.
It is a known problem with indentation-sensitive languages.

The problem is that org-src-font-lock-fontify-block does not strip
indentation from the block. This can be fixed. Although, I planned to
work on this bug together with
https://orgmode.org/list/87ee7c9quk.fsf@localhost.

-- 
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>