D looses in speed to Common Lisp

Justin Whear via Digitalmars-d digitalmars-d at puremagic.com
Mon May 11 14:38:10 PDT 2015


All those allocations aren't helping.  Here's a much more idiomatic D 
version:

import std.stdio, std.bigint;
import std.range;
void main() {
	int n = 100000;
	auto fib1 = recurrence!("a[n-1] + a[n-2]")(BigInt(0), BigInt
(1)).takeExactly(n);
	auto fib2 = recurrence!("a[n-1] + a[n-2]")(BigInt(0), BigInt
(1)).takeExactly(n);

	BigInt sumFib1;
	foreach (e; fib1)
		sumFib1 += e;

	BigInt sumFib2;
	foreach (e; fib2)
		sumFib2 += e;

	writeln(sumFib2 - sumFib1); // 0
}

Timing on my box:
$ time ./fib
0

real	0m1.520s
user	0m1.520s
sys	0m0.000s

Compiling with `ldmd2 fib.d -inline -noboundscheck -O -release`:
$ time ./fib
0

real	0m0.784s
user	0m0.776s
sys	0m0.000s


More information about the Digitalmars-d mailing list