How to implement cache/memoize

[darky]

Hi, congrats with V1! 🎉
How to implement cache/memoize pattern in Gleam for any argument type?

For example, JavaScript:

// Map can use arbitrary types for keys: Objects, Arrays, Functions and so on
const cache = new Map();

const fnUsingCache = (arg) => {
  if (cache.has(arg)) {
    return cache.get(arg)
  }
  
  // resp calculation and cache population
}

For example, Golang:

// Map can use pointers as keys
var cache = map[interface{}]interface{}

func FnUsingCache[T, R Any](arg *T) R {
  if cache[arg] != nil {
    return cache[arg]
  }

  // resp calculation and cache population
}

[lpil]

Hello! In a function language you pass the cache around as we make state explicit.

[darky]

Ok, maybe. But how to implement state for composite types like Records or Functions, which should be used as cache keys?
In JavaScript all reference types can be used as Map keys.
In Golang you can get pointer for Struct or Function and use it as map key
In JVM (Clojure) you can get hash for anything and use it map key
What about Gleam? I found only Dict but it uses strings for keys, which very limited.

[lpil]

Dict does not use strings for keys, you can use anything.

[darky]

Sorry, my bad investigation, thanks!

[lpil]

No prob!!