[Caml-list] non-optional labels in signatures

[Caml-list] non-optional labels in signatures

[Daniel Bünzli]

Hello,

This is certainly a question for Jacques Garrigue. I'm asking out of pure curiosity if there's a particular reason why non-optional labels in signatures don't have the ~ ? Is to save a keystroke ? 

(I happen to make the error of putting them in signatures fairly often) 

Best, 

Daniel 

Re: [Caml-list] non-optional labels in signatures

[Jacques Garrigue]

On 2014/04/22 06:30, Daniel Bünzli wrote:
> 
> Hello,
> 
> This is certainly a question for Jacques Garrigue. I'm asking out of pure curiosity if there's a particular reason why non-optional labels in signatures don't have the ~ ? Is to save a keystroke ? 

This was actually a difficult choice.
In O’Labl (and in OCaml 2.99), there was no ~ in expressions either; a label was an identifier followed by a colon with no space.
However, in OCaml 3.00 we chose to be more conservative, and to preserve compatibility with type annotations (i.e. do not require to add spaces around the colon).
Since the conflict with type annotations was only for expressions, this left the question of what to do with signatures.
There the decision was mostly based on esthetics: a ~ after an arrow does not look good.
I don’t think that saving a keystroke was part of this decision.

Jacques Garrigue

Re: [Caml-list] non-optional labels in signatures

[Daniel Bünzli]

Le mardi, 22 avril 2014 à 01:50, Jacques Garrigue a écrit :
> There the decision was mostly based on esthetics: a ~ after an arrow does not look good.
> I don’t think that saving a keystroke was part of this decision.

Interesting. From a usability point of view I would now have preferred regularity of syntax, but I may be biased, I came to OCaml from Lisp...  

Thanks for the story,

Daniel