Option

Utilities for working with the built-in Option type, which represents optional values — values that may or may not be present.

with_default

Extract a value of type a from an Option<a> by providing a default value for the case when the input is None.

with_default : a -> Option<a> -> awith_default : a -> Option<a> -> a

is_some

Return true if the given value is constructed with Some, and false otherwise.

is_some : Option<a> -> boolis_some : Option<a> -> bool

is_none

Return true if the given value is None, and false otherwise.

is_none : Option<a> -> boolis_none : Option<a> -> bool

option

From a default value of type b, a function of type a -> b, and an Option<a> value, apply the function to the value inside the Some constructor and return the result, or if the value is None, return the default value.

option : b -> (a -> b) -> Option<a> -> boption : b -> (a -> b) -> Option<a> -> b

cat_options

Collect all values contained in Some constructors from a list of Option<a> values, discarding occurrences of None.

cat_options : List<Option<a>> -> List<a>cat_options : List<Option<a>> -> List<a>

list_to_option

Convert a list to an Option<a> by returning Some applied to the first element of the list, or None if the list is empty.

list_to_option : List<a> -> Option<a>list_to_option : List<a> -> Option<a>

option_to_list

Convert an Option<a> value to a list by returning a singleton list containing the value if it is Some, or the empty list if it is None.

option_to_list : Option<a> -> List<a>option_to_list : Option<a> -> List<a>