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Within LTS Haskell 22.23 (ghc-9.6.5)

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1. maybe :: Decoder a -> Decoder (Maybe a)

   dhall	Dhall.Marshal.Decode

   Decode a Maybe.

   >>> input (maybe natural) "Some 1"
   Just 1
   

2. maybe :: b -> (a -> b) -> Maybe a -> b

   numhask	NumHask.Prelude

   The maybe function takes a default value, a function, and a Maybe value. If the Maybe value is Nothing, the function returns the default value. Otherwise, it applies the function to the value inside the Just and returns the result.

   Examples

   Basic usage:

   >>> maybe False odd (Just 3)
   True
   

   >>> maybe False odd Nothing
   False
   

   Read an integer from a string using readMaybe. If we succeed, return twice the integer; that is, apply (*2) to it. If instead we fail to parse an integer, return 0 by default:

   >>> import Text.Read ( readMaybe )
   
   >>> maybe 0 (*2) (readMaybe "5")
   10
   
   >>> maybe 0 (*2) (readMaybe "")
   0
   

   Apply show to a Maybe Int. If we have Just n, we want to show the underlying Int n. But if we have Nothing, we return the empty string instead of (for example) "Nothing":

   >>> maybe "" show (Just 5)
   "5"
   
   >>> maybe "" show Nothing
   ""
   

3. maybe :: b -> (a -> b) -> Maybe a -> b

   prelude-compat	Prelude2010

   The maybe function takes a default value, a function, and a Maybe value. If the Maybe value is Nothing, the function returns the default value. Otherwise, it applies the function to the value inside the Just and returns the result.

   Examples

   Basic usage:

   >>> maybe False odd (Just 3)
   True
   

   >>> maybe False odd Nothing
   False
   

   Read an integer from a string using readMaybe. If we succeed, return twice the integer; that is, apply (*2) to it. If instead we fail to parse an integer, return 0 by default:

   >>> import Text.Read ( readMaybe )
   
   >>> maybe 0 (*2) (readMaybe "5")
   10
   
   >>> maybe 0 (*2) (readMaybe "")
   0
   

   Apply show to a Maybe Int. If we have Just n, we want to show the underlying Int n. But if we have Nothing, we return the empty string instead of (for example) "Nothing":

   >>> maybe "" show (Just 5)
   "5"
   
   >>> maybe "" show Nothing
   ""
   

4. maybe :: b -> (a -> b) -> Maybe a -> b

   foundation	Foundation

   The maybe function takes a default value, a function, and a Maybe value. If the Maybe value is Nothing, the function returns the default value. Otherwise, it applies the function to the value inside the Just and returns the result.

   Examples

   Basic usage:

   >>> maybe False odd (Just 3)
   True
   

   >>> maybe False odd Nothing
   False
   

   Read an integer from a string using readMaybe. If we succeed, return twice the integer; that is, apply (*2) to it. If instead we fail to parse an integer, return 0 by default:

   >>> import Text.Read ( readMaybe )
   
   >>> maybe 0 (*2) (readMaybe "5")
   10
   
   >>> maybe 0 (*2) (readMaybe "")
   0
   

   Apply show to a Maybe Int. If we have Just n, we want to show the underlying Int n. But if we have Nothing, we return the empty string instead of (for example) "Nothing":

   >>> maybe "" show (Just 5)
   "5"
   
   >>> maybe "" show Nothing
   ""
   

5. maybe :: b -> (a -> b) -> Maybe a -> b

   base-prelude	BasePrelude

   The maybe function takes a default value, a function, and a Maybe value. If the Maybe value is Nothing, the function returns the default value. Otherwise, it applies the function to the value inside the Just and returns the result.

   Examples

   Basic usage:

   >>> maybe False odd (Just 3)
   True
   

   >>> maybe False odd Nothing
   False
   

   Read an integer from a string using readMaybe. If we succeed, return twice the integer; that is, apply (*2) to it. If instead we fail to parse an integer, return 0 by default:

   >>> import Text.Read ( readMaybe )
   
   >>> maybe 0 (*2) (readMaybe "5")
   10
   
   >>> maybe 0 (*2) (readMaybe "")
   0
   

   Apply show to a Maybe Int. If we have Just n, we want to show the underlying Int n. But if we have Nothing, we return the empty string instead of (for example) "Nothing":

   >>> maybe "" show (Just 5)
   "5"
   
   >>> maybe "" show Nothing
   ""
   

6. maybe :: b -> (a -> b) -> Maybe a -> b

   mixed-types-num	Numeric.MixedTypes.PreludeHiding

   The maybe function takes a default value, a function, and a Maybe value. If the Maybe value is Nothing, the function returns the default value. Otherwise, it applies the function to the value inside the Just and returns the result.

   Examples

   Basic usage:

   >>> maybe False odd (Just 3)
   True
   

   >>> maybe False odd Nothing
   False
   

   Read an integer from a string using readMaybe. If we succeed, return twice the integer; that is, apply (*2) to it. If instead we fail to parse an integer, return 0 by default:

   >>> import Text.Read ( readMaybe )
   
   >>> maybe 0 (*2) (readMaybe "5")
   10
   
   >>> maybe 0 (*2) (readMaybe "")
   0
   

   Apply show to a Maybe Int. If we have Just n, we want to show the underlying Int n. But if we have Nothing, we return the empty string instead of (for example) "Nothing":

   >>> maybe "" show (Just 5)
   "5"
   
   >>> maybe "" show Nothing
   ""
   

7. maybe :: b -> (a -> b) -> Maybe a -> b

   rebase	Rebase.Prelude

   The maybe function takes a default value, a function, and a Maybe value. If the Maybe value is Nothing, the function returns the default value. Otherwise, it applies the function to the value inside the Just and returns the result.

   Examples

   Basic usage:

   >>> maybe False odd (Just 3)
   True
   

   >>> maybe False odd Nothing
   False
   

   Read an integer from a string using readMaybe. If we succeed, return twice the integer; that is, apply (*2) to it. If instead we fail to parse an integer, return 0 by default:

   >>> import Text.Read ( readMaybe )
   
   >>> maybe 0 (*2) (readMaybe "5")
   10
   
   >>> maybe 0 (*2) (readMaybe "")
   0
   

   Apply show to a Maybe Int. If we have Just n, we want to show the underlying Int n. But if we have Nothing, we return the empty string instead of (for example) "Nothing":

   >>> maybe "" show (Just 5)
   "5"
   
   >>> maybe "" show Nothing
   ""
   

8. maybe :: b -> (a -> b) -> Maybe a -> b

   LambdaHack	Game.LambdaHack.Core.Prelude

   The maybe function takes a default value, a function, and a Maybe value. If the Maybe value is Nothing, the function returns the default value. Otherwise, it applies the function to the value inside the Just and returns the result.

   Examples

   Basic usage:

   >>> maybe False odd (Just 3)
   True
   

   >>> maybe False odd Nothing
   False
   

   Read an integer from a string using readMaybe. If we succeed, return twice the integer; that is, apply (*2) to it. If instead we fail to parse an integer, return 0 by default:

   >>> import Text.Read ( readMaybe )
   
   >>> maybe 0 (*2) (readMaybe "5")
   10
   
   >>> maybe 0 (*2) (readMaybe "")
   0
   

   Apply show to a Maybe Int. If we have Just n, we want to show the underlying Int n. But if we have Nothing, we return the empty string instead of (for example) "Nothing":

   >>> maybe "" show (Just 5)
   "5"
   
   >>> maybe "" show Nothing
   ""
   

9. maybe :: b -> (a -> b) -> Maybe a -> b

   cabal-install-solver	Distribution.Solver.Compat.Prelude

   The maybe function takes a default value, a function, and a Maybe value. If the Maybe value is Nothing, the function returns the default value. Otherwise, it applies the function to the value inside the Just and returns the result.

   Examples

   Basic usage:

   >>> maybe False odd (Just 3)
   True
   

   >>> maybe False odd Nothing
   False
   

   Read an integer from a string using readMaybe. If we succeed, return twice the integer; that is, apply (*2) to it. If instead we fail to parse an integer, return 0 by default:

   >>> import Text.Read ( readMaybe )
   
   >>> maybe 0 (*2) (readMaybe "5")
   10
   
   >>> maybe 0 (*2) (readMaybe "")
   0
   

   Apply show to a Maybe Int. If we have Just n, we want to show the underlying Int n. But if we have Nothing, we return the empty string instead of (for example) "Nothing":

   >>> maybe "" show (Just 5)
   "5"
   
   >>> maybe "" show Nothing
   ""
   

10. maybe :: b -> (a -> b) -> Maybe a -> b

    dimensional	Numeric.Units.Dimensional.Prelude

    The maybe function takes a default value, a function, and a Maybe value. If the Maybe value is Nothing, the function returns the default value. Otherwise, it applies the function to the value inside the Just and returns the result.

    Examples

    Basic usage:

    >>> maybe False odd (Just 3)
    True
    

    >>> maybe False odd Nothing
    False
    

    Read an integer from a string using readMaybe. If we succeed, return twice the integer; that is, apply (*2) to it. If instead we fail to parse an integer, return 0 by default:

    >>> import Text.Read ( readMaybe )
    
    >>> maybe 0 (*2) (readMaybe "5")
    10
    
    >>> maybe 0 (*2) (readMaybe "")
    0
    

    Apply show to a Maybe Int. If we have Just n, we want to show the underlying Int n. But if we have Nothing, we return the empty string instead of (for example) "Nothing":

    >>> maybe "" show (Just 5)
    "5"
    
    >>> maybe "" show Nothing
    ""
    

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