On 05/09/2015 05:52 PM, Dennis Ritchie wrote:
On Saturday, 9 May 2015 at 14:15:21 UTC, Ali Çehreli wrote:
On 05/09/2015 04:59 AM, Dennis Ritchie wrote:
On Saturday, 9 May 2015 at 11:49:48 UTC, Timon Gehr wrote:
assert((function int(int
x)=>x?x*__traits(parent,{})(x-1):1)(10)==3628800);
Thanks. Yes, it is similar to what I wanted :)
Also interesting:
http://rosettacode.org/wiki/Y_combinator#D
I think that code was improved by Timon Gehr as well.
Ali
Yes, it's much better.
Well, it is much slower due to all the allocated closures, owed to the
fact that the implementations of 'fix' on that page are expected to
mirror a particular famous implementation in untyped lambda calculus.
In case you have a use for 'fix', a more efficient implementation might be:
auto fix(S,T...)(S delegate(T) delegate (S delegate(T)) f){
S delegate(T) g=(T a){ assert(0,"f is too eager."); };
return g=f((T a)=>g(a));
}
(In particular, this will only allocate two closures for the plumbing
instead of a number of them linear in the number of recursive invocations.)
Even something like Common Lisp.
(Be aware that Common Lisp implementations typically have better garbage
collectors than what is available for D.)
