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It’s a gem providing algebraic types and pattern matching seamlessly integrates with standard features Ruby.

What is it good for?

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