agnostic/internals/constants

Gleam’s runtime representation of types in JavaScript is not quite clever enough to notice that empty containers or nullary constructors can be initialised once and reused every time they are needed.

This might sound like a micro-optimisation, but things like empty lists and dicts are incredibly common just in Lustre’s internals, so having constant references to them makes a huge difference over the lifetime of a program.

pub const empty_list: List(b)

pub const error_nil: Result(c, Nil)

pub fn singleton_list(item: a) -> List(a)