1
1
mirror of https://github.com/github/semantic.git synced 2024-12-24 23:42:31 +03:00

Add a merge function to compute a Term from a Diff.

This commit is contained in:
Rob Rix 2016-06-27 12:37:27 -04:00
parent 3f6cab2abc
commit 9829d2df84

View File

@ -24,6 +24,12 @@ diffSum patchCost diff = sum $ fmap patchCost diff
diffCost :: Diff a annotation -> Integer
diffCost = diffSum $ patchSum termSize
merge :: (Patch (Term leaf annotation) -> Term leaf annotation) -> Diff leaf annotation -> Term leaf annotation
merge transform = cata algebra . fmap transform
where algebra :: FreeF (CofreeF (Syntax leaf) (Both annotation)) (Term leaf annotation) (Term leaf annotation) -> Term leaf annotation
algebra (Pure p) = p
algebra (Free (annotations :< syntax)) = cofree (Both.fst annotations :< syntax)
beforeTerm :: Diff leaf annotation -> Maybe (Term leaf annotation)
beforeTerm = cata algebra
where algebra :: FreeF (CofreeF (Syntax leaf) (Both annotation)) (Patch (Term leaf annotation)) (Maybe (Term leaf annotation)) -> Maybe (Term leaf annotation)