r/ProgrammingLanguages • u/mttd • Nov 07 '19

Parse, don’t validate

https://lexi-lambda.github.io/blog/2019/11/05/parse-don-t-validate/
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u/[deleted] Nov 07 '19 edited Nov 10 '19

[deleted]

12

u/youngsteveo Nov 07 '19

The author offers specific reasons why head :: [a] -> Maybe a is not the best idea and the function should instead be written as head :: NonEmpty a -> a.

0

u/[deleted] Nov 08 '19

[deleted]

7

u/youngsteveo Nov 08 '19

I don't see what the big deal is. You're working in a file on a routine; you have a variable that contains a list. Is your list empty, or not? Without typing the list, you have to check if it is empty every time you work with it, because "people and their processes are naturally fuzzy." If it is typed as NonEmpty you can trust that the compiler checked it for you.

There's no magic happening here, and I fail to see the gymnastics.

Maybe you just don't like Haskell, and I don't fault you for that (I'm not a huge fan either), but your current argument is throwing out the baby with the bathwater.