Add isJustAnd

tomjaguarpaw · Oct 20, 2023 · c01ec60 · c01ec60
1 parent 8f051d7
commit c01ec60
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diff --git a/src/Opaleye/Internal/MaybeFields.hs b/src/Opaleye/Internal/MaybeFields.hs
@@ -142,6 +142,14 @@ traverseMaybeFields query = proc mfInput -> do
 
  where a `implies` b = Opaleye.Internal.Operators.not a .|| b
 
+isJustAnd ::
+ MaybeFields a ->
+ (a -> Opaleye.Field.Field SqlBool) ->
+ Opaleye.Field.Field SqlBool
+isJustAnd ma cond = matchMaybe ma $ \case
+ Nothing -> Opaleye.SqlTypes.sqlBool False
+ Just a -> cond a
+
 optional :: SelectArr i a -> SelectArr i (MaybeFields a)
 optional = Opaleye.Internal.Lateral.laterally (optionalInternal (MaybeFields . isNotNull))
  where isNotNull = Opaleye.Internal.Operators.not . Opaleye.Field.isNull

diff --git a/src/Opaleye/MaybeFields.hs b/src/Opaleye/MaybeFields.hs
@@ -19,6 +19,7 @@ module Opaleye.MaybeFields (
  fromMaybeFields,
  maybeFields,
  maybeFieldsToNullable,
+ isJustAnd,
  -- * Creating a 'Select' which returns 'MaybeFields'
  Opaleye.Join.optional,
  Opaleye.MaybeFields.traverseMaybeFields,