type-cache.go

func typeCache[T any](compute func(t reflect.Type) T) func(t reflect.Type) T {
	cache := map[reflect.Type]T{}
	return func(t reflect.Type) T {
		if v, ok := cache[t]; ok {
			return v
		}
		v := compute(t) // but compute cant recurse
		cache[t] = v
		return v
	}
}