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Learn Red ? Fundamentals of Red
book

Learn Red ? Fundamentals of Red

by Ivo Balbaert
May 2018
Beginner content levelBeginner
252 pages
6h 19m
English
Packt Publishing
Content preview from Learn Red ? Fundamentals of Red

Choosing with |

If the starting character is either an X or a Y, such as in X123 or Y108, we can use "X" | "Y", where | stands for or,  so the expression reads like "X" or "Y":

xy: ["X" | "Y"]parse "X123" [xy some digit]    ;== trueparse "Y108" [xy some digit]    ;== true

| can be used for a small number of choices, but if there are more than a few choices, it is better to make a charset and use that in the pattern:

uz: charset "UVWXYZ"parse "X123" [uz some digit]    ;== trueparse "V456" [uz some digit]    ;== true

=> Now answer questions 4 and 5 from the Questions section.

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Publisher Resources

ISBN: 9781789130706Supplemental Content