ludic/docs/language/list/list-contains.md

id	name	category	kind	tokens	sig	tip	order	ns	member
list-contains	List.contains	list	namespace-method	List.contains	List.contains(s, v) -> bool	Whether a value appears in a slice.	7	List	contains

Scans s and returns true if any element equals v. Comparison is by value for scalar elements (ints, entities, booleans) and by identity for reference elements. Use it for membership tests — has this tile been visited, is this entity already in the target list, is the achievement unlocked. It is a linear scan, so for very large or hot-path sets a dedicated structure will be faster.

Parameters:

• s — the slice to search
• v — the value to look for

program Visited {
  state VisitedState {
    seen: []int = new []int
  }

  handler Step(visited_st: VisitedState) phase Update {
    let tile = 42
    if not List.contains(visited_st.seen, tile) {
      List.push(visited_st.seen, tile)
    }
  }
}