Option -- the class of all key-value pairs K => V

Description

Such pairs are used as optional arguments for functions.

i1 : o = Limit => 5

o1 = Limit => 5

o1 : Option

i2 : peek o

o2 = Option{Limit, 5}

There is also a way to make new hash tables from lists of key-value pairs.

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

o3 = HashTable{a => 5}
               b => 7

o3 : HashTable

i4 : keys ht

o4 = {a, b}

o4 : List

i5 : values ht

o5 = {5, 7}

o5 : List

i6 : pairs ht

o6 = {(a, 5), (b, 7)}

o6 : List

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

i7 : o#0

o7 = Limit

o7 : Symbol

i8 : o#1

o8 = 5

directSum(Option) -- see directSum -- direct sum of modules or maps
Option ++ Option -- see directSum -- direct sum of modules or maps
installAssignmentMethod(Symbol,HashTable,HashTable,Option) -- see installing assignment methods -- install methods assignment to the value of an operator
installAssignmentMethod(Symbol,HashTable,Option) -- see installing assignment methods -- install methods assignment to the value of an operator
package(Option) -- see package -- get containing package
substitute(Ideal,Option) -- see substitute -- substituting values for variables
substitute(Matrix,Option) -- see substitute -- substituting values for variables
substitute(Module,Option) -- see substitute -- substituting values for variables
substitute(RingElement,Option) -- see substitute -- substituting values for variables
substitute(Vector,Option) -- see substitute -- substituting values for variables

The object Option is a type, with ancestor classes BasicList < Thing.

The source of this document is in Macaulay2Doc/functions/options-doc.m2:88:0.