Picat Functions vs. Predicates 2

Question 1

Which syntax correctly defines a Picat function that returns the square of X?

Accepted Answer

square(X) = X * X

Answer

Picat functions are defined with `=` between the head and the return expression.

Question 2

In Picat, what happens when you call a function but no clause pattern matches the arguments?

Accepted Answer

An existence error or pattern-match failure is thrown

Answer

If no function clause matches, Picat raises an exception because functions must return a value.

Question 3

A Picat predicate clause uses `?=>` instead of `=>`. What does this indicate?

Accepted Answer

The predicate is nondeterministic and may leave choice points

Answer

`?=>` marks a nondeterministic clause that keeps a choice point, allowing backtracking.

Question 4

Can a Picat function be embedded directly inside an arithmetic expression such as `Y = f(X) + 3`?

Accepted Answer

Yes, because functions return values usable in expressions

Answer

Picat functions return values and can appear anywhere an expression is expected.

Question 5

Which of the following is a valid way to call a Picat predicate `greet(Name)`?

Accepted Answer

greet("Alice")

Answer

Predicates are called as statements; they do not return values and cannot appear inside expressions.

Picat Practice Test