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Within LTS Haskell 24.39 (ghc-9.10.3)

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  1. mapMaybeWithKey :: (Key -> a -> Maybe b) -> IntMap a -> IntMap b

    containers Data.IntMap.Lazy

    Map keys/values and collect the Just results.

    let f k _ = if k < 5 then Just ("key : " ++ (show k)) else Nothing
    mapMaybeWithKey f (fromList [(5,"a"), (3,"b")]) == singleton 3 "key : 3"
    

  2. mapWithKey :: (Key -> a -> b) -> IntMap a -> IntMap b

    containers Data.IntMap.Lazy

    Map a function over all values in the map.

    let f key x = (show key) ++ ":" ++ x
    mapWithKey f (fromList [(5,"a"), (3,"b")]) == fromList [(3, "3:b"), (5, "5:a")]
    

  3. mapMaybeMissing :: forall (f :: Type -> Type) x y . Applicative f => (Key -> x -> Maybe y) -> WhenMissing f x y

    containers Data.IntMap.Merge.Lazy

    Map over the entries whose keys are missing from the other map, optionally removing some. This is the most powerful SimpleWhenMissing tactic, but others are usually more efficient.

    mapMaybeMissing :: (Key -> x -> Maybe y) -> SimpleWhenMissing x y
    
    mapMaybeMissing f = traverseMaybeMissing (\k x -> pure (f k x))
    
    but mapMaybeMissing uses fewer unnecessary Applicative operations.

  4. mapMissing :: forall (f :: Type -> Type) x y . Applicative f => (Key -> x -> y) -> WhenMissing f x y

    containers Data.IntMap.Merge.Lazy

    Map over the entries whose keys are missing from the other map.

    mapMissing :: (k -> x -> y) -> SimpleWhenMissing x y
    
    mapMissing f = mapMaybeMissing (\k x -> Just $ f k x)
    
    but mapMissing is somewhat faster.

  5. mapWhenMatched :: forall (f :: Type -> Type) a b x y . Functor f => (a -> b) -> WhenMatched f x y a -> WhenMatched f x y b

    containers Data.IntMap.Merge.Lazy

    Map covariantly over a WhenMatched f x y.

  6. mapWhenMissing :: forall (f :: Type -> Type) a b x . (Applicative f, Monad f) => (a -> b) -> WhenMissing f x a -> WhenMissing f x b

    containers Data.IntMap.Merge.Lazy

    Map covariantly over a WhenMissing f x.

  7. mapMaybeMissing :: forall (f :: Type -> Type) x y . Applicative f => (Key -> x -> Maybe y) -> WhenMissing f x y

    containers Data.IntMap.Merge.Strict

    Map over the entries whose keys are missing from the other map, optionally removing some. This is the most powerful SimpleWhenMissing tactic, but others are usually more efficient.

    mapMaybeMissing :: (k -> x -> Maybe y) -> SimpleWhenMissing k x y
    
    mapMaybeMissing f = traverseMaybeMissing (\k x -> pure (f k x))
    
    but mapMaybeMissing uses fewer unnecessary Applicative operations.

  8. mapMissing :: forall (f :: Type -> Type) x y . Applicative f => (Key -> x -> y) -> WhenMissing f x y

    containers Data.IntMap.Merge.Strict

    Map over the entries whose keys are missing from the other map.

    mapMissing :: (k -> x -> y) -> SimpleWhenMissing k x y
    
    mapMissing f = mapMaybeMissing (\k x -> Just $ f k x)
    
    but mapMissing is somewhat faster.

  9. mapWhenMatched :: forall (f :: Type -> Type) a b x y . Functor f => (a -> b) -> WhenMatched f x y a -> WhenMatched f x y b

    containers Data.IntMap.Merge.Strict

    Map covariantly over a WhenMatched f k x y.

  10. mapWhenMissing :: forall (f :: Type -> Type) a b x . Functor f => (a -> b) -> WhenMissing f x a -> WhenMissing f x b

    containers Data.IntMap.Merge.Strict

    Map covariantly over a WhenMissing f k x.

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