std.option
A type that can represent the abscence of a value
Types
type Option a =
| None
| Some a
Option
represents a value which may not exist.
Values
Eq a
defines equality (==) on a
Ord a
defines an ordering on a
A Functor
represents an action on a parameterized type which does not
change the structure with the mapped type.
The following laws should hold:
map id == id
map (f << g) == map f << map g
#[implicit]
let applicative : Applicative Option
A Functor
with application.
The following laws should hold:
wrap id <*> v = v
wrap (<<) <*> u <*> v <*> w = u <*> (v <*> w)
wrap f <*> wrap x = wrap (f x)
u <*> wrap y = wrap (\g -> g x) <*> u
#[implicit]
let alternative : Alternative Option
A monoid on applicative functors.
A generalised interface for imperatively sequencing actions
Show a
represents a conversion function from a
to a readable string.
Operations over a data structure that can be folded which means that a functions gets called on
each element to reduce the structure to a single value (Array
, List
and Map
are all Foldable
)