FunctionalCollections

Functional and persistent data structures for Julia. This is a work in progress and is currently not optimized for performance.

NOTE: The master branch of FunctionalCollections is for Julia v0.7 and up. For earlier Julia versions please use FunctionalCollections v0.3.x.

Installation

julia> Pkg.add("FunctionalCollections")

julia> using FunctionalCollections

Exports

Collection         | Abbrev
----------------------------
PersistentVector   | pvec
PersistentHashMap  | phmap
PersistentArrayMap |
PersistentSet      | pset
PersistentList     | plist
PersistentQueue    | pqueue

src/FunctionalCollections.jl contains all of the package's exports, though many built-ins are also implemented.

PersistentVector

Persistent vectors are immutable, sequential, random-access data structures, with performance characteristics similar to arrays.

julia> v = @Persistent [1, 2, 3, 4, 5]
Persistent{Int64}[1, 2, 3, 4, 5]

Since persistent vectors are immutable, "changing" operations return a new vector instead of modifying the original.

julia> append(v, [6, 7])
Persistent{Int64}[1, 2, 3, 4, 5, 6, 7]

# v hasn't changed
julia> v
Persistent{Int64}[1, 2, 3, 4, 5]

Persistent vectors are random-access structures, and can be indexed into just like arrays.

julia> v[3]
3

But since they're immutable, it doesn't make sense to define index assignment (v[3] = 42) since assignment implies change. Instead, assoc returns a new persistent vector with some value associated with a given index.

julia> assoc(v, 3, 42)
Persistent{Int64}[1, 2, 42, 4, 5]

Three functions, push, peek, and pop, make up the persistent vector stack interface. push adds a single element (whereas append adds all elements in the given collection, starting from the left), peek returns the last element of the vector, and pop returns a new vector without the last element.

julia> push(v, 6)
Persistent{Int64}[1, 2, 3, 4, 5, 6]

julia> peek(v)
5

julia> pop(v)
Persistent{Int64}[1, 2, 3, 4]

Persistent vectors also support iteration and higher-order sequence operations.

julia> for el in @Persistent ["foo", "bar", "baz"]
           println(el)
       end
foo
bar
baz

julia> map(x -> x * 2, v)
Persistent{Int64}[2, 4, 6, 8, 10]

julia> filter(iseven, v)
Persistent{Int64}[2, 4]

PersistentHashMap

Persistent hash maps are immutable, unordered, associative structures, similar to the built-in Dict type.

julia> name = @Persistent Dict(:first => "Zach", :last => "Allaun")
Persistent{Symbol, String}[last => Allaun, first => Zach]

They can be queried in a manner similar to the dictionaries.

julia> name[:first]
"Zach"

julia> get(name,