Major differences from Prolog seem to be as follows: Prolog always evaluates through unification (at least in theory). Verse is evaluated through reduction, including the unifications! This means a). there is a sublanguage in verse that doesn't do unification at all... it should have similar performance to a functional programming language like Haskell. b) verse is deterministic... the same prolog programs can at least theoretically produce two different answers to the same input. Verse has a defined denotational semantics (prolog has most of a defined operational semantics, but that's a different kind of thing). c). Verse an be type checked at compile time! It seems typechecking verse is undecidable, so presumably some type checks will be moved to run time, but lots of type checking can be done at compile time.
> Prolog always evaluates through unification (at least in theory).
What do you mean? The actual "computational" part of Prolog lies more in resolution than in unification. Unification does not "evaluate" in any sense of the word I'm familiar with.
> the same prolog programs can at least theoretically produce two different answers to the same input.
What do you mean? Do you mean through side effects, or are you suggesting that Prolog's evaluation order or something else is not fully specified and deterministic? You would be wrong about the latter.
EDIT:
> Verse has a defined denotational semantics
What do you mean? Verse (or rather the underlying calculus VC) has a rewrite semantics. Rewriting is pretty operational and not at all denotational.
