Using reduce for factorial, seems to require iota, not a bad things per se, with ulongs:

	reduce!"a*b"(1, iota(1, n + 1))

works fine. Now switch to BigInt:

	reduce!"a*b"(one, iota(one, n + one))

fails to compile, one and n + one are of different types. Problem is that one is immutable but n + one is not. I can't remember how to create an immutable value as an expression so:

	immutable BigInt v = n + one;
	reduce!"a*b"(one, iota(one, v))

now I get an error telling me that I can't use iota because BigInt is not a float or an integer. Is this a known bug? Yes it is: https://issues.dlang.org/show_bug.cgi?id=6447

Does anyone know how to fix this 3.5 year old bug that is a blocker for doing anything with factorial and Fibonacci Series.?

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