On 12/2/10 4:47 PM, Iavor Diatchki wrote:
Hi, You have it exactly right, and I don't think that there's a particularly deep reason to prefer the one over the other. It seems that computer science people tend to go with the (product-function) terminology, while math people seem to prefer the (sum-product) version, but it is all largely a matter of taste.
The product=function,sum=pair terminology comes from a certain interpretation of dependent types in set theory. I believe this originated with Per Martin-Löf's work, though I don't have any citations on hand. That terminology conflicts with the standard product=pair,sum=either terminology of functional languages, however. So folks from a functional background tend to prefer: dependent function, dependent product, sum; whereas folks from a set-theoretic background tend to prefer product, sum, <no name>/union. -- Live well, ~wren