Option -- the class of all pairs x => y

Option -- the class of all pairs x => y

The type Option is a member of the class Type. Each object of class Option is called an option. Each option is also a member of class BasicList.

More general types (whose methods may also apply) :

BasicList -- the class of all basic lists

Such pairs are used as optional arguments for functions. There is also a way to make new hash tables with new by providing a list of option pairs.

i1 : a => 5



o1 = a => 5



o1 : Option

i2 : peek (a => 5)



o2 = Option{a,5}

i3 : new HashTable from {a => 5, b => 7}



o3 = HashTable{a => 5}

               b => 7



o3 : HashTable

These pairs are implemented as lists, so that if z is x => y, then x is z#0 and y is z#1.

See also:

classes and types -- an overview

=> -- produce an Option

Functions and methods returning a an option :

Methods for using an option :