Support a lambda pattern

lib/typeprof/core/ast.rb

@@ -396,6 +396,7 @@ def self.create_pattern_node(raw_node, lenv)
 
       when :array_node then ArrayNode.new(raw_node, lenv) # for %w[foo bar]
       when :range_node then RangeNode.new(raw_node, lenv) # TODO: support range pattern correctly
+      when :lambda_node then LambdaNode.new(raw_node, lenv) # TODO: match by `===` instead of ignoring the subject
 
       else
         raise "unknown pattern node type: #{ raw_node.type }"

scenario/patterns/lambda_pat.rb

@@ -0,0 +1,16 @@
+## update: test.rb
+def check(x)
+  case x
+  in ->(i) { i == 0 }
+    :zero
+  in Integer
+    :int
+  end
+end
+
+check(0)
+
+## assert
+class Object
+  def check: (Integer) -> (:int | :zero)
+end