Re: How do I ..

[Brian Rogoff <bpr@best.com>]

On Sat, 18 Dec 1999, skaller wrote:

> I'm confused:
> 
>        Objective Caml version 2.99 (99/12/08)
> 
> # let f (lx:x : int) = x + 1;;
> Syntax error

Try "#modern true;;" at the top level, or compile with the -modern switch. 

I hope this modern/classic mode distinction is just a temporary thing. 

> Here, I have an argument x, a label lx, and a type declaration int.
> What's the error? Can't I both label an argument, and also type it?

Modern mode handles it. I would have thought classic mode would too, since
you're not reordering arguments, but I see that's not the case. Explanation
anyone?

> The whitespace rule is a bit weird .. but it makes some sense,
> when compared with 'a for a type variable: the ' must come
> right in front of the a, with no white space, so I guess
> I can live with lablx:x as a labelled argument .. :-)
> 
> At first, I got really confused by the difference between
> a label, and the name of the argument. Until I realised,
> you can't use the name of the argument as a label, because
> it would imply all arguments were labelled. In the tutorial,
> it would be nice to replace ambiguous examples like:
> 
> 	let f x:x ... 

I think that the label is "x:" and the argument name is "x", with the 
sugar that :x is equivalent to x:x. At least that's how I interpreted 
the rules.

-- Brian