Algebrick
It’s a gem providing algebraic types and pattern matching seamlessly integrates with standard features Ruby.
- Documentation: http://blog.pitr.ch/algebrick
- Source: https://github.com/pitr-ch/algebrick
- Blog: http://blog.pitr.ch/blog/categories/algebrick/
What is it good for?
- Defining data structures.
- Algebraic types play nice with JSON serialization and deserialization. It is ideal for defining message-based cross-process communication.
- and more…
Quick example
Let’s define a Tree
ruby
Tree = Algebrick.type do |tree|
variants Empty = atom,
Leaf = type { fields Integer },
Node = type { fields tree, tree }
end
Now types Tree(Empty | Leaf | Node), Empty, Leaf(Integer) and Node(Tree, Tree) are defined.
Let’s add a method, don’t miss the pattern matching example.
ruby
module Tree
# compute depth of a tree
def depth
match self,
(on Empty, 0),
(on Leaf, 1),
# ~ will store and pass matched parts to variables left and right
(on Node.(~any, ~any) do |left, right|
1 + [left.depth, right.depth].max
end)
end
end
Method defined in module Tree are passed down to all values of type Tree
ruby
Empty.depth # => 0
Leaf[10].depth # => 1
Node[Leaf[4], Empty].depth # => 2
Node[Empty, Node[Leaf[1], Empty]].depth # => 3