Julia collections

By defining five functions on your citable collection, you can make them interoperate with dozens of generic Julia functions for working with collections of data.

What you need to define

Thes are the five functions you want to define:

using Base.Iterators
import Base: length
import Base: eltype
import Base: iterate
import Base: filter
import Base.Iterators: reverse

In many cases, you can implement these functions with a single line of code.

• length: return the number of items in your collection
• eltype: return the type of object your collection contains
• iterate: you need to implement two required methods, one for an initial state and taking a single parameter for the collection, a second with two parameters, giving the collection and some state information. If your collection is indexed (e.g., an Array type), your state information might simply be an index value.
• filter: you can use collect to create an Array on your citable collection and filter the resulting Array.
• reverse: similarly, just collect the values of your collection and pass that to reverse

What you get

Some of the functions this gives you are:

functions returning iterators:

• collect
• drop
• dropwhile
• enumerate
• flatten
• partition
• product
• rest
• take
• takewhile
• zip

functions returning other kinds of value:

• accumulate
• all
• allunique
• any
• argmax
• argmin
• collect
• count
• extrema
• first
• in
• isempty
• map
• reduce
• foldl
• foldr
• maximum
• map
• mapfoldl
• mapfoldr
• mapreduce
• minimum
• prod
• unique
• ∌