pure-lang-users

[pure-lang-users] when and with syntax

[Eddie R. <er...@bm...>]

Hi Albert,

What do you think about the following addition to syntax? If there is exactly one statement
inside of a 'with' or when 'block,' we could leave off the 'end.'

Instead of 

with
  rule1
end;

we could have

with rule1;

e.r.
 

Re: [pure-lang-users] when and with syntax

[Albert G. <Dr....@t-...>]

Eddie Rucker wrote:
> What do you think about the following addition to syntax? If there is exactly one statement
> inside of a 'with' or when 'block,' we could leave off the 'end.'

Yeah, that would be convenient, but unfortunately it's not possible, 
since the grammar would become ambiguous (or non-LALR at least).

Albert

-- 
Dr. Albert Gr"af
Dept. of Music-Informatics, University of Mainz, Germany
Email:  Dr....@t-..., ag...@mu...
WWW:    http://www.musikinformatik.uni-mainz.de/ag

Re: [pure-lang-users] when and with syntax

[Eddie R. <er...@bm...>]

On Mon, 2008-07-21 at 05:33 +0200, Albert Graef wrote:
> Eddie Rucker wrote:
> > What do you think about the following addition to syntax? If there is exactly one statement
> > inside of a 'with' or when 'block,' we could leave off the 'end.'
> 
> Yeah, that would be convenient, but unfortunately it's not possible, 
> since the grammar would become ambiguous (or non-LALR at least).
> 
> Albert
> 
Ok, I forgot Pascal used 'begin end' pairs to define a block.
Personally, I prefer 'when end' to 'when begin end.' However, 'when {}'
isn't bad but I figure you'll use '{}' for streams.

e.r.

Re: [pure-lang-users] when and with syntax

[Albert G. <Dr....@t-...>]

Eddie Rucker wrote:
> Personally, I prefer 'when end' to 'when begin end.'

Me too, obviously. :) Pascal's begin ... end goes back to Algol, but 
Wirth himself later realized that properly bracketed statements are 
better and more economic, so that's what Modula and Oberon have.

> However, 'when {}' isn't bad but I figure you'll use '{}' for streams.

Either that, or structs, or generalized list comprehensions. In any case 
it seems like a good idea to keep {} unused for now.

Albert

-- 
Dr. Albert Gr"af
Dept. of Music-Informatics, University of Mainz, Germany
Email:  Dr....@t-..., ag...@mu...
WWW:    http://www.musikinformatik.uni-mainz.de/ag