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# A value wrapper adding status information to any value
# Status can be :ok or :error, we are thusly implementing
# what is expressed in Elixir/Erlang as result tuples and
# in Haskell as `Data.Either`
class Result
attr_reader :status, :value
class << self
def ok value
make :ok, value
end
def error value
make :error, value
end
def new *args
raise NoMethodError, "No default constructor for #{self}"
end
private
def make status, value
allocate.tap do | o |
o.instance_exec do
@status = status
@value = value
end
end
end
end
def ok?; status == :ok end
def == other
other.kind_of?(self.class) && other.status == status && other.value == value
end
end
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