Runtime assertions for Ruby
literal.fun
ruby
Introduce `_Unit` type
+59
+12
lib/literal/types.rb
+12
lib/literal/types.rb
···
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)
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end
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# The unit type is a type that matches only the same object
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def _Unit(object)
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UnitType.new(object)
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end
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# Nilable version of `_Unit`
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def _Unit?(...)
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_Nilable(
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_Unit(...)
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)
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end
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def _Void
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VoidType::Instance
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end
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lib/literal/types/unit_type.rb
+30
lib/literal/types/unit_type.rb
···
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# frozen_string_literal: true
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# @api private
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class Literal::Types::UnitType
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include Literal::Type
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EQUAL_METHOD = BasicObject.instance_method(:equal?)
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def initialize(object)
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@object = object
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freeze
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end
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attr_reader :object
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def ===(value)
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EQUAL_METHOD.bind_call(@object, value)
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end
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def >=(other)
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case other
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when Literal::Types::UnitType
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EQUAL_METHOD.bind_call(@object, other.object)
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else
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false
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end
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end
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freeze
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end
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test/types/_unit.test.rb
+17
test/types/_unit.test.rb
···
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# frozen_string_literal: true
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include Literal::Types
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test "===" do
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object = -> { "hello" }
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assert _Unit(object) === object
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refute _Unit(object) === -> { "hello" }
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end
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test "hierarchy" do
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object = "a"
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assert_subtype _Unit(object), _Unit(object)
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refute_subtype _Unit(object), _Unit(+"a")
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end