Hacking ruby patterns to be first-class objects that can be passed around

code.rb

# need to "pin" the variable, but this only works with the lambda because
# pattern matching falls back to case matchint (=== on any object in ruby,
# which is NOT "identical object" as in JS)
def matches1(pat,x)
  case x
  in ^pat
    puts true
  else
    puts false
  end
end

# a "more honest" implementation, same behavior
def matches2(pat,x)
  case x
  when pat 
    puts true
  else
    puts false
  end
end

# these don't work
matches1({a: Integer}, {a: 5, b: 6})
matches1({a: Integer}, {a: "hello", b: 6})

# all of the below works

my_pattern = -> { _1 in {a: Integer} }

# more verbose
# my_pattern = ->(value) { value in {a: Integer} }

# more verbose
# my_pattern = lambda do |value|
#   value in {a: Integer}
# end


matches1(my_pattern, {a: 5, b: 6})
matches1(my_pattern, {a: "hello", b: 6})
matches2(my_pattern, {a: 5, b: 6})
matches2(my_pattern, {a: "hello", b: 6})