[Caml-list] ocp-indent begin/end behaviour?

[Caml-list] ocp-indent begin/end behaviour?

[Malcolm Matalka]

I have the following code that I'm using ocp-indent to indent:

let () =
  match Random.int 10 with
    | 1 -> begin
        zoom ();
        baz ()
      end
    | 2 ->
      ()

The zoom and baz are indented "double", and I cannot figure out how to
undo that.  I'd like the begin/end to have no effect on indentation at
all.  Is this a bug or am I doing something wrong?

/Malcolm

Re: [Caml-list] ocp-indent begin/end behaviour?

[Goswin von Brederlow]

On Thu, Sep 15, 2016 at 07:01:00PM +0000, Malcolm Matalka wrote:
> I have the following code that I'm using ocp-indent to indent:
> 
> let () =
>   match Random.int 10 with
>     | 1 -> begin
>         zoom ();
>         baz ()
>       end
>     | 2 ->
>       ()
> 
> The zoom and baz are indented "double", and I cannot figure out how to
> undo that.  I'd like the begin/end to have no effect on indentation at
> all.  Is this a bug or am I doing something wrong?
> 
> /Malcolm

Double seems right since the match case indents and begin/end also
needs to indent since it creates a sub block. Consider this:

let () =
  match Random.int 10 with
    | 1 ->
      bar ();
      begin
        zoom ();
        baz ()
      end;
      foo ()
    | 2 ->
      ()

Note: The only reason to use begin/end for a match case is if you have
another match inside I believe.

MfG
	Goswin

Re: [Caml-list] ocp-indent begin/end behaviour?

[Louis Gesbert]

On jeudi 15 septembre 2016 19:01:00 CEST Malcolm Matalka wrote:
> I have the following code that I'm using ocp-indent to indent:
> 
> let () =
>   match Random.int 10 with
> 
>     | 1 -> begin
> 
>         zoom ();
>         baz ()
>       end
> 
>     | 2 ->
> 
>       ()
> 
> The zoom and baz are indented "double", and I cannot figure out how to
> undo that.  I'd like the begin/end to have no effect on indentation at
> all.  Is this a bug or am I doing something wrong?
> 
> /Malcolm

ocp-indent is all about compromises and trying to keep programs visually 
consistent. Also, it attempts to keep the configuration options to a minimum 
so that their effects can still be easily understood, and styles don't diverge 
too much.

In this case, `zoom (); baz ()` is inside two scopes that can be closed 
individually (`->` and `begin/end`). So, as Goswin pointed out, without that 
extra indentation the `end` would have to be either at the level of the `|` or 
that of `zoom ();`, which isn't totally accurate, and in either case, if you 
were to add `; some more stuff` after `end`, you couldn't get a proper 
indentation without backtracking anymore.

So it's not a bug, but a design choice -- it's impossible to satisfy everyone 
anyway (-- or it would end up like LaTeX). Note that it's designed to play 
well with interactive use + partially manual indent (e.g. if you move `zoom 
();`, `baz ()` will follow)

Best,
Louis Gesbert -- OCamlPro