Picat Functions vs. Predicates 3

Question 1

In Picat, which operator separates the head from the body in a deterministic predicate clause?

Accepted Answer

=>

Answer

`=>` is the neck operator for a deterministic predicate clause in Picat.

Question 2

Consider `len([]) = 0` and `len([_|T]) = 1 + len(T)`. Why must `len` be a function rather than a predicate here?

Accepted Answer

Because it produces a return value used in an arithmetic expression

Answer

The result of `len` is used directly in `1 + len(T)`, requiring it to be a function that yields a value.

Question 3

Which statement about Picat functions is FALSE?

Accepted Answer

A function can be nondeterministic by using `?=`

Answer

Picat does not have a `?=` nondeterministic function neck; functions are deterministic constructs.

Question 4

A Picat predicate `max_list(List, Max)` binds `Max` to the largest element. How is this different from a function approach?

Accepted Answer

The predicate unifies the result via an extra output argument instead of returning it

Answer

Predicates communicate results through extra arguments bound by unification, not through a return value.

Question 5

Given `double(X) = 2 * X`, what does `Y = double(5) + double(3)` evaluate to?

Accepted Answer

Y = 16

Answer

`double(5)` returns 10 and `double(3)` returns 6, so `Y = 16`.

Picat Practice Test