Chase (elm_playground.Chase)

val ways : 
  Grid_move.grid ->
  open_:((int * int) -> bool) ->
  Grid_move.mover ->
  Grid_move.dir list

val toward : 
  Grid_move.grid ->
  open_:((int * int) -> bool) ->
  goal:(int * int) ->
  Grid_move.mover ->
  Grid_move.mover

val at_random : 
  Grid_move.grid ->
  open_:((int * int) -> bool) ->
  int ->
  Grid_move.mover ->
  Grid_move.mover

val next_random : int -> int