Transformation of Applicative Specifications into Imperative ...

CHAPTER 10. EXAMPLES OF TRANSFORMATIONS
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end
push : Element × Stack → Stack
push(elem, stack) ≡ 〈elem〉 stack,
pop : Stack ∼ → Stack
pop(stack) ≡ tl stack
pre ∼ is_empty(stack),
top : Stack ∼ → Element
top(stack) ≡ hd stack
pre ∼ is_empty(stack)
scheme I_STACK =
class
type
Stack = Element ∗ ,
Element
end
variable
stack : Stack
value
empty : Unit → write stack Unit
empty() ≡ stack := 〈〉,
is_empty : Unit → read stack Bool
is_empty() ≡ stack = 〈〉,
push : Element → read stack write stack Unit
push(elem) ≡ stack := 〈elem〉 stack,
pop : Unit ∼ → read stack write stack Unit
pop() ≡ stack := tl stack
pre ∼ is_empty(),
top : Unit ∼ → read stack Element
top() ≡ hd stack
pre ∼ is_empty()
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