Stupid little iota of an idea

[Andrei Alexandrescu]

On 2/9/11 7:46 AM, Nick Sabalausky wrote:
> "spir"<denis.spir at gmail.com>  wrote in message
> news:mailman.1422.1297254724.4748.digitalmars-d at puremagic.com...
>>
>> Side-question: what is actually 1..5 as of now for a thing? Or is it
>> conceptually "unconstructed" by rewriting to (probably) an ordinary for
>> loop? Anyway, the point above applies to language-side semantics, whatever
>> optimisation may happen.
>>
>
> AIUI: Syntactically, it doesn't exist at all, at least not by itself. It's
> just part of one of the foreach syntaxes:
>
>    'foreach' '(' {declaration list} ';' {expression} '..' {expression} ')'
>
> and also part of one of the slice syntaxes:
>
>    (from the docs:)
>    PostfixExpression [ AssignExpression .. AssignExpression ]
>
> Although it's possible I've understood it wrong.
>
> Don't have a clue how it's handled beyond that though.

Indeed, a..b is just punctuation in the two grammatical constructs you 
mentioned.

Your proposal has indeed been made a couple of times, first probably by 
bearophile - but then what did bearophile /not/ propose? (Meaning this 
in good fun.) I think it would be okay to move iota into druntime and 
enact the rewrite. But this would improve the language by such a small 
iota...

I buy the orthogonality argument as much as you do. foreach is not 
orthogonal because it is a short form of for, which is not orthogonal 
because it is a short form of while, which is not orthogonal because it 
is a short form of a scope with if/goto at the top.

If a..b would be rewritten into iota(a, b) that would still be 
non-orthogonal because one could express one thing in two ways. 
Ironically, it's more orthogonal to leave things as they are: you have 
iota(a, b) as the general concept and you have a..b as punctuation in 
two grammatical constructs.

But the most important question is: if the rewrite were done, to what 
extent would that improve your use of the language? Integral intervals 
do occur outside foreach and slices, but quite infrequently. In those 
cases you'd gain by replacing iota(a, b) with a..b. Is this significant?


Andrei