Re: [pure-lang-users] Proposed syntax changes

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

Jeremy Voorhis wrote:
> OMG $$++

That gives me a syntax error. ;-) But look at this marvel!

   > OMG = id;
   > OMG $ (Im,feeling,silly)!2 $ OMG ponies;
   silly ponies

Ok, I take it that $$ is the consensus.

> Regarding tuples, I've always thought of tuples as representing
> structures with a fixed number of slots, and that this was a perfectly
> valid thing to do.

That's what they are, but Pure also allows you to piece them together 
and manipulate them in any way you see fit. Also, in Haskell et al 
tuples are a builtin data structure, whereas in Pure they are just an 
algebraic type like any other (and are in fact completely defined in the 
prelude).

> My Pure abilities are still weak, so somebody help
> me out – I assumed tagged tuples would be useful for representing
> algebraic types in a dynamic language like Pure, since they are good
> for matching on.

That's what poor Erlang programmers have to do. In Pure all your data is 
in fact a term algebra, so any function symbol can act as a constructor 
and you don't need this kludge. E.g., nil and bin act as constructors in 
the following example:

nullary nil;

insert nil y		= bin y nil nil;
insert (bin x L R) y	= bin x (insert L y) R if y<x;
			= bin x L (insert R y) otherwise;

(That works without having to declare anything, except a nullary symbol 
like nil so that the compiler can distinguish it from a variable when it 
occurs on the lhs of an eqn.)

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