Fibonacci with ranges

[Russel Winder]

On Sat, 2011-03-12 at 09:33 +0000, Russel Winder wrote:
[ . . . ]
> Interestingly, or not, the code:
> 
> long declarative ( immutable long n ) {
>   return take ( recurrence ! ( "a[n-1] + a[n-2]" ) ( 0L , 1L ) , n ) ;
> }
> 
> results in the return statement delivering:
> 
> rdmd --main -unittest fibonacci_d2.d
> fibonacci_d2.d(15): Error: template std.range.take(R) if (isInputRange!(Unqual!(R)) && !isSafelySlicable!(Unqual!(R)) && !is(Unqual!(R) T == Take!(T))) does not match any function template declaration
> fibonacci_d2.d(15): Error: template std.range.take(R) if (isInputRange!(Unqual!(R)) && !isSafelySlicable!(Unqual!(R)) && !is(Unqual!(R) T == Take!(T))) cannot deduce template function from argument types !()(Recurrence!(fun,long,2u),immutable(long))
> 
> which seems deeply impenetrable for mere mortals.

Sorry I needed to add the driver code:

  foreach ( item ; data ) {
    assert ( declarative ( item[0] ) == item[1] ) ;
  }

within a unittest block. 
-- 
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 russel.org.uk
London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder
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