Re:Patterns.dev
by zelphirkalt on Thursday December 11, 2025 @09:02PM
(#46240036)
Instead of defining a Visitor interface and then making objects to implement the interface and then passing those objects to whatever traverses a graph or iterates through something, you pass the function, that will be called, by whatever traverses a graph or iterates through something.
[ Parent
| on HN ]
Kind of like how sum types and matching are implemented in library code? Example from D here:
Fahrenheit toFahrenheit(Temperature t)
{
return Fahrenheit(
t.match!(
(Fahrenheit f) => f.degrees,
(Celsius c) => c.degrees * 9.0/5 + 32,
(Kelvin k) => k.degrees * 9.0/5 - 459.4
)
);
}