I am trying to round up cases when it makes sense to use a map (set of key-value entries). So far I have five categories (see below). Assuming more exist, what are they?
Please limit each answer to one unique category, put up an example, and vote up the fascinating ones.
Property values (like a bean)
age -> 30
sex -> male
loc -> calgary
Histograms
peter -> 1
john -> 7
paul -> 5
Presence, with O(1) performance
peter -> 1
john -> 1
paul -> 1
Functions
peter -> treatPeter()
john -> dealWithJohn()
paul -> managePaul()
Conversion
peter -> pierre
john -> jean
paul -> paul