Astro Hacker News - Union Types and Option Types (2025)

gnabgib |next [-]

(2025) And about CopperLang (203 points, 3 days ago, 120 comments) https://news.ycombinator.com/item?id=50308754

p1necone |next |previous [-]

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 |root |parent [-]

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.

ks2048 |next |previous [-]

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.

DonaldPShimoda |root |parent |next [-]

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.

tylermk04 |root |parent |previous [-]

Rosetta code is often helpful. Not exactly for language features, necessarily: https://rosettacode.org/wiki/Monads/Maybe_monad

cardboardguru |next |previous [-]

Swift has already answered all these questions.

direwolf20 |next |previous [-]

i read Onion Types

smnrchrds |root |parent |next [-]

Philomena Cunk on Programming

https://www.youtube.com/shorts/XK_D7Z-cKZ4

budro |root |parent |next |previous [-]

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 |root |parent [-]

Shrek would argue the layers are a feature not a bug

SoleilAbsolu |root |parent |next |previous [-]

So shallot be...

speed_spread |root |parent |previous [-]

No matter how you cut them, they'll make you cry.