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Published in:
2021 | OriginalPaper | Chapter
10. Lists and Recursion
Authors : Donald Sannella, Michael Fourman, Haoran Peng, Philip Wadler
Published in: Introduction to Computation
Publisher: Springer International Publishing
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Abstract
Recall that the list notation
[4,6,8] is just shorthand for the expression 4:(6:(8:[])). So, every list can be written using : and []
. In fact, every list can be written using : and [] in just one way. That fact is what makes pattern matching work on lists. Given a list l and a pattern p built using variables, [], : and literals, there is at most one way to match p against l. That match gives values to the variables in p. It might not match, if p requires a list that’s longer than l, or if p contains a literal that doesn’t match the value in the corresponding position in l.