Zipping Lists with Repetition -- a puzzle Koen Lindstrm Claessen - - PowerPoint PPT Presentation

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Nov 25, 2023 268 likes •334 views

Zipping Lists with Repetition -- a puzzle Koen Lindstrm Claessen type Nat = Int data List a = Unit a | List a :++: List a | Rep Nat (List a) same length zip :: List a -> List a -> List (a,b) minimal size len :: List a -> Integer

SLIDE 1

Zipping Lists with Repetition

- a puzzle

Koen Lindström Claessen

SLIDE 2

zip :: List a -> List a -> List (a,b) data List a = Unit a | List a :++: List a | Rep Nat (List a)

same length minimal size

type Nat = Int

SLIDE 3

len :: List a -> Integer len (Unit x) = 1 len (p :++: q) = len p + len q len (Rep n p) = n * len p size :: List a -> Integer size (Unit x) = 1 size (p :++: q) = size p + size q size (Rep _ p) = size p

SLIDE 4

zip :: List a -> List a -> List (a,b)

polynomial in the size

f the result (?)

best heuristic independent of the number of repetitions

SLIDE 5