Hoogle Search

Within LTS Haskell 24.66 (ghc-9.10.3)

Note that Stackage only displays results for the latest LTS and Nightly snapshot. Learn more.

Exact lookup

1. listToMaybe :: [a] -> Maybe a

   rio	RIO.Prelude

   The listToMaybe function returns Nothing on an empty list or Just a where a is the first element of the list.

   Examples

   Basic usage:

   >>> listToMaybe []
   Nothing
   

   >>> listToMaybe [9]
   Just 9
   

   >>> listToMaybe [1,2,3]
   Just 1
   

   Composing maybeToList with listToMaybe should be the identity on singleton/empty lists:

   >>> maybeToList $ listToMaybe [5]
   [5]
   
   >>> maybeToList $ listToMaybe []
   []
   

   But not on lists with more than one element:

   >>> maybeToList $ listToMaybe [1,2,3]
   [1]
   

2. listToMaybe :: [a] -> Maybe a

   errors	Control.Error

   The listToMaybe function returns Nothing on an empty list or Just a where a is the first element of the list.

   Examples

   Basic usage:

   >>> listToMaybe []
   Nothing
   

   >>> listToMaybe [9]
   Just 9
   

   >>> listToMaybe [1,2,3]
   Just 1
   

   Composing maybeToList with listToMaybe should be the identity on singleton/empty lists:

   >>> maybeToList $ listToMaybe [5]
   [5]
   
   >>> maybeToList $ listToMaybe []
   []
   

   But not on lists with more than one element:

   >>> maybeToList $ listToMaybe [1,2,3]
   [1]
   

3. headMay :: [a] -> Maybe a

   errors	Control.Error

   No documentation available.

4. lastMay :: [a] -> Maybe a

   errors	Control.Error

   No documentation available.

5. listToMaybe :: [a] -> Maybe a

   Cabal-syntax	Distribution.Compat.Prelude

   No documentation available.

6. safeHead :: [a] -> Maybe a

   Cabal-syntax	Distribution.Utils.Generic

   A total variant of head.

7. safeLast :: [a] -> Maybe a

   Cabal-syntax	Distribution.Utils.Generic

   A total variant of last.

8. listToMaybe :: [a] -> Maybe a

   relude	Relude.Monad.Reexport

   The listToMaybe function returns Nothing on an empty list or Just a where a is the first element of the list.

   Examples

   Basic usage:

   >>> listToMaybe []
   Nothing
   

   >>> listToMaybe [9]
   Just 9
   

   >>> listToMaybe [1,2,3]
   Just 1
   

   Composing maybeToList with listToMaybe should be the identity on singleton/empty lists:

   >>> maybeToList $ listToMaybe [5]
   [5]
   
   >>> maybeToList $ listToMaybe []
   []
   

   But not on lists with more than one element:

   >>> maybeToList $ listToMaybe [1,2,3]
   [1]
   

9. listToMaybe :: [a] -> Maybe a

   ghc-internal	GHC.Internal.Data.Maybe

   The listToMaybe function returns Nothing on an empty list or Just a where a is the first element of the list.

   Examples

   Basic usage:

   >>> listToMaybe []
   Nothing
   

   >>> listToMaybe [9]
   Just 9
   

   >>> listToMaybe [1,2,3]
   Just 1
   

   Composing maybeToList with listToMaybe should be the identity on singleton/empty lists:

   >>> maybeToList $ listToMaybe [5]
   [5]
   
   >>> maybeToList $ listToMaybe []
   []
   

   But not on lists with more than one element:

   >>> maybeToList $ listToMaybe [1,2,3]
   [1]
   

10. listToMaybe :: [a] -> Maybe a

    protolude	Protolude

    The listToMaybe function returns Nothing on an empty list or Just a where a is the first element of the list.

    Examples

    Basic usage:

    >>> listToMaybe []
    Nothing
    

    >>> listToMaybe [9]
    Just 9
    

    >>> listToMaybe [1,2,3]
    Just 1
    

    Composing maybeToList with listToMaybe should be the identity on singleton/empty lists:

    >>> maybeToList $ listToMaybe [5]
    [5]
    
    >>> maybeToList $ listToMaybe []
    []
    

    But not on lists with more than one element:

    >>> maybeToList $ listToMaybe [1,2,3]
    [1]
    

Page 2 of many | Previous | Next