Maybe

Summary

Maybe
Functions
map	Transforms a maybe value by using the specified mapping function.
get	Returns the value associated with the maybe or crashes the program.
isJust	Returns true if the maybe value is not nothing
isNothing	Returns true if the maybe value is nothing
count	Returns 0 if the maybe value is nothing, 1 otherwise
foldl	Evaluates the equivalent of List:foldl for a maybe
foldr	Evaluates the equivalent of List:foldr for a maybe
iter	Executes a function for a maybe value

Functions

map

Transforms a maybe value by using the specified mapping function.

Type signature

<'a,'b>(('a) -> 'b, maybe<'a>) -> maybe<'b>

Parameters

f : (‘a) -> ‘b	The mapping function
maybeVal : maybe<’a>	The maybe value

Returns

The transformed maybe value.

get

Returns the value associated with the maybe or crashes the program.

Type signature

<'a>(maybe<'a>) -> 'a

Parameters

maybeVal : maybe<’a>

The maybe value

Returns

The value inside of the maybe.

isJust

Returns true if the maybe value is not nothing

Type signature

<'a>(maybe<'a>) -> bool

Parameters

maybeVal : maybe<’a>

The maybe value

Returns

True if the maybe value is not nothing, false otherwise

isNothing

Returns true if the maybe value is nothing

Type signature

<'a>(maybe<'a>) -> bool

Parameters

maybeVal : maybe<’a>

The maybe value

Returns

True if the maybe evalue is nothing, false otherwise.

count

Returns 0 if the maybe value is nothing, 1 otherwise

Type signature

<'a>(maybe<'a>) -> uint8

Parameters

maybeVal : maybe<’a>

The maybe value

Returns

The number of items stored in the count

foldl

Evaluates the equivalent of List:foldl for a maybe

Type signature

<'t,'state>(('t, 'state) -> 'state, 'state, maybe<'t>) -> 'state

Parameters

f : (‘t, ‘state) -> ‘state	The folding function
initState : ‘state	The initial state
maybeVal : maybe<’t>	The maybe value

Returns

The final state returned by f

foldr

Evaluates the equivalent of List:foldr for a maybe

Type signature

<'t,'state>(('t, 'state) -> 'state, 'state, maybe<'t>) -> 'state

Parameters

f : (‘t, ‘state) -> ‘state	The folding function
initState : ‘state	The initial state
maybeVal : maybe<’t>	The maybe value

Returns

The final state returned by f

iter

Executes a function for a maybe value

Type signature

<'a>(('a) -> unit, maybe<'a>) -> unit

Parameters

f : (‘a) -> unit	The function to apply to the value
maybeVal : maybe<’a>	The maybe value

Returns

Unit