find -package:protolude

find :: Foldable t => (a -> Bool) -> t a -> Maybe a

base Data.List Data.Foldable, relude Relude.Foldable.Reexport

The find function takes a predicate and a structure and returns the leftmost element of the structure matching the predicate, or Nothing if there is no such element.

Examples

Basic usage:

>>> find (> 42) [0, 5..]
Just 45

>>> find (> 12) [1..7]
Nothing

find :: (Word8 -> Bool) -> ByteString -> Maybe Word8

bytestring Data.ByteString Data.ByteString.Lazy, rio RIO.ByteString RIO.ByteString.Lazy

O(n) The find function takes a predicate and a ByteString, and returns the first element in matching the predicate, or Nothing if there is no such element.

find f p = case findIndex f p of Just n -> Just (p ! n) ; _ -> Nothing

find :: (Char -> Bool) -> ByteString -> Maybe Char

bytestring Data.ByteString.Char8 Data.ByteString.Lazy.Char8

O(n) The find function takes a predicate and a ByteString, and returns the first element in matching the predicate, or Nothing if there is no such element.

find :: (Word8 -> Bool) -> ShortByteString -> Maybe Word8

bytestring Data.ByteString.Short Data.ByteString.Short.Internal

O(n) The find function takes a predicate and a ShortByteString, and returns the first element in matching the predicate, or Nothing if there is no such element.

find f p = case findIndex f p of Just n -> Just (p ! n) ; _ -> Nothing

find :: (Char -> Bool) -> Text -> Maybe Char

text Data.Text, rio RIO.Text

O(n) The find function takes a predicate and a Text, and returns the first element matching the predicate, or Nothing if there is no such element.

find :: (Char -> Bool) -> Text -> Maybe Char

text Data.Text.Lazy, rio RIO.Text.Lazy

O(n) The find function takes a predicate and a Text, and returns the first element in matching the predicate, or Nothing if there is no such element.

find :: (a -> Bool) -> Vector a -> Maybe a

vector Data.Vector Data.Vector.Strict

O(n) Yield Just the first element matching the predicate or Nothing if no such element exists.

find :: forall a (v :: Type -> Type) . (a -> Bool) -> Bundle v a -> Maybe a

vector Data.Vector.Fusion.Bundle

Yield Just the first element matching the predicate or Nothing if no such element exists.

find :: forall m a (v :: Type -> Type) . Monad m => (a -> Bool) -> Bundle m v a -> m (Maybe a)

vector Data.Vector.Fusion.Bundle.Monadic

Yield Just the first element that satisfies the predicate or Nothing if no such element exists.

find :: Monad m => (a -> Bool) -> Stream m a -> m (Maybe a)

vector Data.Vector.Fusion.Stream.Monadic

find :: Vector v a => (a -> Bool) -> v a -> Maybe a

vector Data.Vector.Generic, rio RIO.Vector

O(n) Yield Just the first element matching the predicate or Nothing if no such element exists.

find :: Prim a => (a -> Bool) -> Vector a -> Maybe a

vector Data.Vector.Primitive

O(n) Yield Just the first element matching the predicate or Nothing if no such element exists.

find :: Storable a => (a -> Bool) -> Vector a -> Maybe a

vector Data.Vector.Storable

O(n) Yield Just the first element matching the predicate or Nothing if no such element exists.

find :: Unbox a => (a -> Bool) -> Vector a -> Maybe a

vector Data.Vector.Unboxed

O(n) Yield Just the first element matching the predicate or Nothing if no such element exists.

find :: Monad m => (a -> Bool) -> ConduitT a o m (Maybe a)

conduit Data.Conduit.Combinators

Find the first matching value. Subject to fusion

find :: Point s a -> ST s a

ghc GHC.Data.UnionFind

Return the canonical element of an equivalence class Point.

find :: Monad m => (a -> Bool) -> Producer a m () -> m (Maybe a)

pipes Pipes.Prelude

Find the first element of a Producer that satisfies the predicate

find :: (a -> Bool) -> Fold a (Maybe a)

foldl Control.Foldl

(find predicate) returns the first element that satisfies the predicate or Nothing if no element satisfies the predicate

find :: (Word8 -> Bool) -> Fold ByteString (Maybe Word8)

foldl Control.Foldl.ByteString

(find predicate) returns the first byte that satisfies the predicate or Nothing if no byte satisfies the predicate

find :: (Char -> Bool) -> Fold Text (Maybe Char)

foldl Control.Foldl.Text

(find predicate) returns the first character that satisfies the predicate or Nothing if no character satisfies the predicate

find :: Container c e => (e -> Bool) -> c e -> [IndexOf c]

hmatrix Numeric.LinearAlgebra.Data

Find index of elements which satisfy a predicate

>>> find (>0) (ident 3 :: Matrix Double)
[(0,0),(1,1),(2,2)]

find :: Foldable t => (a -> Bool) -> t a -> Maybe a

rio RIO.List

The find function takes a predicate and a structure and returns the leftmost element of the structure matching the predicate, or Nothing if there is no such element.

find :: (a -> Bool) -> Vector a -> Maybe a

rio RIO.Vector.Boxed

O(n) Yield Just the first element matching the predicate or Nothing if no such element exists.

find :: Storable a => (a -> Bool) -> Vector a -> Maybe a

rio RIO.Vector.Storable

O(n) Yield Just the first element matching the predicate or Nothing if no such element exists.

find :: Unbox a => (a -> Bool) -> Vector a -> Maybe a

rio RIO.Vector.Unboxed

O(n) Yield Just the first element matching the predicate or Nothing if no such element exists.