[net.lang.prolog] 'setof' Again ...

Pereira%SRI-AI@sri-unix.UUCP (11/01/83)

Some contributors to this Digest have suggested that using 'setof'
rather than 'findall' is just a matter of taste, thus justifying
their use of the name 'setof' for 'findall'. In previous notes,
I gave clear examples that show this is NOT a matter of taste:

- 'setof' has a proper semantics in terms of finite failure,
   'findall' does not;

- interchanging goals in a program with 'findall' may produce
  different solutions, but not with 'setof'.

Warren's 'setof' is RIGHT in a way that 'findall' isn't. Please
stop muddling a simple matter !

-- Fernando Pereira

PS: Now don't come back and start arguing about what 'right' means.
We've been subjected to more than enough Humpty Dumpty semantics.