Too many constraints?

[Christopher Heuer]

Working on generate-constraints, and for something like bif, we could generate a lot of constraints. For example:

[[test]] = boolean

[[bif(test then else)]] = [[then]]

[[bif(test then else)]] = [[else]]

[[then]] = [[else]]

Should the last one be included? I don't think it's technically necessary for the expression to unify but it is something that can be concluded at this step. Is it a problem to include extra constraints like this one?

[Dan Burton]

It shouldn't be a problem. During unification, [[bif(test then else)]] will get replaced with [[then]], thus the third constraint will turn into [[then]] = [[else]]. Then you replace [[then]] with [[else]], and the fourth constraint will turn into [[else]] = [[else]], which is the "identical idenfiers" unification case, and it will simply be discarded as unnecessary.

 

But since it is logically redundant with constraints 2 and 3, I'd leave constraint 4 out anyways.

Dan Burton
801-513-1596

[Bryan Morse]

That's correct. Having additional constraints doesn't hurt anything as long as they're mutually consistent, but you normally want to keep it as simple as possible.