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Diffstat (limited to 'Propellor/Property.hs')
| -rw-r--r-- | Propellor/Property.hs | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/Propellor/Property.hs b/Propellor/Property.hs index e7ec704d..c2a8972e 100644 --- a/Propellor/Property.hs +++ b/Propellor/Property.hs @@ -33,6 +33,16 @@ combineProperties desc ps = Property desc $ go ps NoChange FailedChange -> return FailedChange _ -> go ls (r <> rs) +-- | Combines together two properties, resulting in one property +-- that ensures the first, and if the first succeeds, ensures the second. +-- The property uses the description of the first property. +before :: Property -> Property -> Property +p1 `before` p2 = Property (propertyDesc p1) $ do + r <- ensureProperty p1 + case r of + FailedChange -> return FailedChange + _ -> ensureProperty p2 + -- | Makes a perhaps non-idempotent Property be idempotent by using a flag -- file to indicate whether it has run before. -- Use with caution. |