I've looked at Gleam before but it didn't seem to have any mechanism for dynamic dispatch like interfaces or type classes. Did it change in the meantime?

▲

stuartaxelowen 12 hours ago | parent | next [-]

The answer I’ve seen is “just pass structs of functions around”, which is just one step more explicit than the implicit version we’re all use to, but honestly I kinda like it to free ourselves of all the ceremony around generics.

▲

lpil 12 hours ago | parent [-]

It’s discouraged to pass around structs of functions to replicate type classes in Gleam. Instead the preference is to not type class style patterns in your projects, favouring a concrete style instead.

	▲	stuartaxelowen 42 minutes ago \| parent [-]
		Does that mean pass every needed function as a parameter? Or just don’t write generic functionality?

▲

lpil 12 hours ago | parent | prev [-]

Gleam has first class functions, so it has dynamic dispatch.

Both of type classes and interfaces desugar to high order functions, so anything you write with them can be written with first class functions, though with a less concise API.

▲

the_duke 12 hours ago | parent [-]

What you are saying is: no, it doesn't.

Of course dynamic dispatch can be implemented in almost every language. The Linux kernel uses dynamic dispatch with C!

But that's a hack, not a language feature.

	▲	array_key_first an hour ago \| parent \| next [-]
		It's not a "hack" because many language DO NOT let you store functions with state. Gleam does, I write PHP, and that does as well. PHP has interfaces and whatnot, but a lot of the time I do polymorphism by just having a class that has Closure members. When you can arbitrarily pass around functions like that, it's basically equivalent to an interface or abstract class, with a bit more flexibility.
	▲	lpil 12 hours ago \| parent \| prev [-]
		I think you might mean “ad hoc polymorphism” rather than “dynamic dispatch”. Gleam, C, Erlang, etc have the latter, not so much the former.