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

ghc-lib-parser GHC.Data.Strict

No documentation available.
maybe :: b -> (a -> b) -> Maybe a -> b

ghc-lib-parser GHC.Prelude.Basic

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 GHC.Internal.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
""
```
maybe :: Decoder a -> Decoder (Maybe a)

dhall Dhall.Marshal.Decode

Decode a Maybe.
```
>>> input (maybe natural) "Some 1"
Just 1
```
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 GHC.Internal.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
""
```
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 GHC.Internal.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
""
```
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 GHC.Internal.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
""
```
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 GHC.Internal.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
""
```
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 GHC.Internal.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
""
```
maybe :: b -> (a -> b) -> Maybe a -> b

incipit-base Incipit.Base

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 GHC.Internal.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
""
```

ghc-lib-parser	GHC.Data.Strict

ghc-lib-parser	GHC.Prelude.Basic

dhall	Dhall.Marshal.Decode

foundation	Foundation

prelude-compat	Prelude2010

mixed-types-num	Numeric.MixedTypes.PreludeHiding

LambdaHack	Game.LambdaHack.Core.Prelude

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

incipit-base	Incipit.Base

maybe :: (SymVal a, SymVal b) => SBV b -> (SBV a -> SBV b) -> SMaybe a -> SBV b

sbv	Data.SBV.Maybe

Case analysis for symbolic Maybes. If the value isNothing, return the default value; if it isJust, apply the function.

>>> maybe 0 (`sMod` 2) (sJust (3 :: SInteger))
1 :: SInteger

>>> maybe 0 (`sMod` 2) (sNothing :: SMaybe Integer)
0 :: SInteger

>>> let f = uninterpret "f" :: SInteger -> SBool

>>> prove $ \x d -> maybe d f (sJust x) .== f x
Q.E.D.

>>> prove $ \d -> maybe d f sNothing .== d
Q.E.D.

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