Allow improveIf of con/undet when only one constructor #748
Conversation
| when (length argTypes /= length es1) $ internalError ("improveIf Con/Undet:" ++ ppReadable (argTypes, es1)) | ||
| let mkUndet t = icUndetAt (getIdPosition i2) t u | ||
| (es', bs) <- mapAndUnzipM (\(t, e1) -> improveIf f t cnd e1 (mkUndet t)) (zip argTypes es1) | ||
| -- unambiguous improvement because the ICCon has propagated out |
There was a problem hiding this comment.
great comment, thank you for that
There was a problem hiding this comment.
This isn't my comment. The body of this clause is copied from an earlier clause, that optimizes arms containing the same constructor, line 4359. The comment comes from there.
This duplication could be avoided by having the new clause (that I'm adding) only convert the else _ to else (C _ _ _), and then recursively call improveIf to do the merging of C e1 e2 e3 with C _ _ _ (for example). But most of the clause is just computing the types of the arguments to C, so most of the lines in the body of the clause would be duplicated anyway. It's not much more to just go ahead and do the full optimization, and avoid any duplicated work from the recursive call.
| @@ -0,0 +1,45 @@ | |||
| // This example comes from GitHub Issue #742 | |||
There was a problem hiding this comment.
Maybe just add that it's testing the effect of this optimization on compilation time rather than directly?
This fixes #742 by allowing
improveIfto mergeICConandICUndetwhen the type has only one constructor, by pushing the conditional into the constructor arguments.