Take and website

[Russel Winder]

On Tue, 2012-07-24 at 13:56 -0400, Andrei Alexandrescu wrote:
[…]
> The example is:
> 
> int[] arr1 = [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ];
> auto s = take(arr1, 5);
> assert(s.length == 5);
> assert(s[4] == 5);
> assert(equal(s, [ 1, 2, 3, 4, 5 ][]));
> 
> Were you referring to this? Example code does not need to be generic, 
> and in this case it's fine if the code relies on random access because 
> it uses an array of integers.

That's the one.

s[4] relies on the fact that arr1 is an array:

 ( takeExactly ( recurrence ! ( "a[n-1] + a[n-2]" ) ( 0L , 1L ) , cast
( size_t ) ( n + 1 ) ) ) [ n ]

fails with operator [] not defined, I find I have to:

array ( takeExactly ( recurrence ! ( "a[n-1] + a[n-2]" ) ( 0L , 1L ) ,
cast ( size_t ) ( n + 1 ) ) ) [ n ] 

So the functions available on the results of a take depends on the data
input. In one sense obvious, in another sense a total fubar since it is
not necessarily clear what the types are in more complex situations.

-- 
Russel.
=============================================================================
Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder at ekiga.net
41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel at winder.org.uk
London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder
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