Section 4.3

Question 1

True or false: Constant pattern matching in Miranda is strict.

Answer 1

True

Question 2

True or false: Sum pattern matching in Miranda is strict.

Answer 2

True

Question 3

True or false: Product pattern matching in Miranda is strict.

Answer 3

False

Question 4

True or false: Lazy product matching is less efficient than strict product matching.

Answer 4

True. Applying lazy product matching can require more reductions than strict pattern matching.

Question 5

Why do the semantic equations for pattern matching not include mismatched arguments (e.g a non-product argument applied to a lambda abstraction with a product pattern)?

Answer 5

The evaluation function is defined as an ordinary mathematical function, and such definitions are given only on the function’s domain.

Operationally, the type-checker ensures that functions are never applied to values outside of their domain.

Question 6

What properties of a case expression make efficient implementation possible?

Answer 6

Exhaustiveness and the restriction to simple patterns.

Question 7

Why is exhaustiveness required?

Answer 7

The patterns must be exhaustive so that the unconditional jump on the constructor always succeeds.

Question 8

Why is the simple pattern restriction required?

Answer 8

If the one of the patterns is nested, one can no longer jump on the outermost constructor alone.