Contents

# Let's define a Tree
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.
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.
Empty.depth
Leaf[10].depth
Node[Leaf[4], Empty].depth
Node[Empty, Node[Leaf[1], Empty]].depth

Version data entries

6 entries across 6 versions & 1 rubygems

Version	Path
algebrick-0.7.3	doc/quick_example.in.rb
algebrick-0.7.2	doc/quick_example.in.rb
algebrick-0.7.1	doc/quick_example.in.rb
algebrick-0.7.0	doc/quick_example.in.rb
algebrick-0.6.0	doc/quick_example.in.rb
algebrick-0.5.0	doc/quick_example.in.rb