[SamBam]

I think it's just being confusingly stated. GP already said that reduce could implement map. I think it's merely that reduce can just output a single result, of any type. (Which is already more powerful than map, which must output an array.)

Of course, in fact you could hack anything in any of these, since you could be doing other work in the function called. But I think the general principle is sound.

[thaumasiotes]

> (Which is already more powerful than map, which must output an array.)

Don't tell Common Lisp.