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Chapter 9 - Why use type abbreviation for 'Total' and 'DiscountPercentage'?

bytesource opened this issue · comments

commented

Hi Ian,

After you mentioning the problems with type abbreviations compared to (private) singe-case discriminated unions, I wonder why you chose type abbreviations for Spend and DiscountPercentage on page 128:

type Total = decimal
type DiscountPercentage = decimal

Was this merely to keep the book code a bit shorter, or is there something else I should keep in mind?

Still enjoying your book!

Cheers,

Stefan

commented

It was mainly for brevity but there wasn't any obvious benefit in these cases (function outputs) from using something more complex. Converting them into single-case DUs is relatively easy should you feel the urge to do so.

commented

Thanks, that makes sense. I converted Total to a single-case DU, but kept DiscountPercentage as a type abbreviation, as in the example code it's only used internally.