Programming Language Theory Flashcard

What

Books

Deckpure-lambda-calculus

Question

What's the difference between the call-by-name fixed-point combinator and the call-by-value fixed-point combinator?

Answer

Call-by-name fixed-point combinator - Curry/Y-Combinator:
$Y = λ f . (λ x . f x x) (λ x . f x x)$
-> Used in call-by-name languages because of the lazy evaluation strategy.
-> Not used in call-by-value languages because it always diverges when applied to a function
Call-by-value fixed-point combinator - Z-combinator:
$Z = λ f . (λ x . f (λ v . x x v)) (λ x . f (λ v . x x v))$
-> Used in call-by-value languages.