Union Types and Option Types (2025) (tibleiz.net)
32 pointsby g0xA52A2Aa day ago13 comments
gnabgib a day ago
(2025) And about CopperLang (203 points, 3 days ago, 120 comments) https://news.ycombinator.com/item?id=50308754
p1necone 5 hours ago
One simple but non obvious (at least to me) trick when implementing tagged unions: put the union discriminator/tag at the end, not the beginning - that way a pointer to a union is also a pointer to the value, no need to increment the pointer to point past the tag after discriminating.
beached_whale 4 hours ago
when serializing these things it's generally going to be best to put the tag first though. That way it's cheap to figure out how to parse it.
cardboardguru 2 hours ago
Swift has already answered all these questions.
ks2048 4 hours ago
What is the best source for cross-language description of language features? Eg: “optional types”: which langs have them and how do they work? Same with “union types” etc.
tylermk04 4 hours ago
Rosetta code is often helpful. Not exactly for language features, necessarily:
https://rosettacode.org/wiki/Monads/Maybe_monad
DonaldPShimoda 3 hours ago
There's no single oracle for these things, unfortunately. One common citation is "Types and Programming Languages" by Benjamin Pierce (2002), but otherwise people generally just use the nomenclature of a specific language and hope cross-linguistic adventurers will figure it out. I think there's somewhat less variance with more modern languages, though, so in some ways it's less of an issue than it once was.
direwolf20 5 hours ago
i read Onion Types
SoleilAbsolu 5 hours ago
So shallot be...
budro 4 hours ago
Well poor design can require you to peel off multiple layers of optionals, and so they're often a significant smell just like onions are.
andyferris 3 hours ago
Shrek would argue the layers are a feature not a bug
smnrchrds 3 hours ago
Philomena Cunk on Programming
speed_spread 2 hours ago
No matter how you cut them, they'll make you cry.