A Discussion of Tuple Syntax

[Wyatt]

On Tuesday, 20 August 2013 at 09:02:29 UTC, Mr. Anonymous wrote:
>
> Why not just leave an empty space, like php does:
>
> $info = array('coffee', 'brown', 'caffeine');
> // let's skip to only the third one
> list( , , $power) = $info;
> echo "I need $power!\n";

Bad idea.  It's a visual thing--  quick! How wide is this tuple!?:
#(,front,,,,var,)

How long did it take you to be SURE that it's a seven-tuple?  You 
probably aren't even equipped to measure that so don't worry 
about answering, but I'm guessing you start to appreciate why 
it's a fairly inhumane solution (how drearily typical for PHP).

Ah, but what if it was supposed to be #(,front,,,,,var,)?  Does 
that change your result, now that you're taking the sixth element 
rather than the seventh?  All you did was forget a comma!  By 
contrast:
#(?,front,?,?,?,var,?,?) //at least gives us a better chance of 
parsing it correctly.

My point here is we are human and we are fallible.  The sooner we 
acknowledge and internalise that, the better equipped we are to 
make systems that don't suck for humans to use.

In that sense, I don't even really like this format because it's 
still not especially resilient.  Walter's talk about design that 
eliminates patterns of human error resonated with me quite 
strongly, you see.  But in terms of language consistency it's not 
much different from array literals, so I could accept it as a 
compromise.

-Wyatt