Short-circuit evaluation

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This page is the answer to the task Short-circuit evaluation in the Rosetta Code.

Description (from Rosetta Code)

Assume functions a and b return boolean values, and further, the execution of function b takes considerable resources without side effects, and is to be minimized.

If we needed to compute the conjunction (and):

x = a() and b()

Then it would be best to not compute the value of b() if the value of a() is computed as false, as the value of x can then only ever be false.

Similarly, if we needed to compute the disjunction (or):

y = a() or b()

Then it would be best to not compute the value of b() if the value of a() is computed as true, as the value of y can then only ever be true.

Some languages will stop further computation of boolean equations as soon as the result is known, so-called short-circuit evaluation of boolean expressions

Task

Create two functions named a and b, that take and return the same boolean value.

The functions should also print their name whenever they are called.

Calculate and assign the values of the following equations to a variable in such a way that function b is only called when necessary:

x = a(i) and b(j)
y = a(i) or b(j)

If the language does not have short-circuit evaluation, this might be achieved with nested if statements.

Answer

ShortCircuitEvaluation.png