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Diffstat (limited to 'src/GF/Data/Operations.hs')
| -rw-r--r-- | src/GF/Data/Operations.hs | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/src/GF/Data/Operations.hs b/src/GF/Data/Operations.hs index 6dd78e1bc..d4c13f1f4 100644 --- a/src/GF/Data/Operations.hs +++ b/src/GF/Data/Operations.hs @@ -168,6 +168,14 @@ updatePerhaps old p1 p2 = case (p1,p2) of (_, May a) -> Bad "strange indirection" _ -> unifPerhaps p1 p2 +-- here the value is copied instead of referred to; used for oper types +updatePerhapsHard :: b -> Perhaps a b -> Perhaps a b -> Err (Perhaps a b) +updatePerhapsHard old p1 p2 = case (p1,p2) of + (Yes a, Nope) -> return $ yes a + (May older,Nope) -> return $ may older + (_, May a) -> Bad "strange indirection" + _ -> unifPerhaps p1 p2 + -- binary search trees data BinTree a = NT | BT a (BinTree a) (BinTree a) deriving (Show,Read) |