add predicate and reduce function doc

data/scripts/classes/duck.lua

@@ -99,7 +99,7 @@ end
 
 function Duck:start_chase(feed)
   if self.state == States.CHASE then return end
-  print("duck " .. self.index .. " starting chase")
+  -- print("duck " .. self.index .. " starting chase")
   self.state = States.CHASE
   self.target = feed
   feed.occupied = true

data/scripts/game.lua

@@ -10,16 +10,8 @@ local Duck = require "classes.duck"
 local ducks = List()
 
 local function create_feed(position, direction)
-  print("?")
   local f = Feed.new(position, direction)
   feed:push(f)
-  local eligible_ducks = ducks:filter(
-    function (duck)
-      return duck.state ~= duck.STATES.CHASE
-    end
-  )
-  if eligible_ducks:is_empty() then return end
-  eligible_ducks[1]:start_chase(f)
 end
 
 local function delete_feed(f)
@@ -29,11 +21,17 @@ end
 local function duck_seek_feed(duck)
   local eligible_feeds = feed:filter(
     function (f)
-      return feed.occupied == false
+      return f.occupied == false
     end
   )
   if eligible_feeds:is_empty() then return end
-  duck:start_chase(eligible_feeds[1])
+  duck:start_chase(
+    eligible_feeds:sorted(
+      function(a, b)
+        return a.position:distance_squared_to(duck.position) < b.position:distance_squared_to(duck.position)
+      end
+    ):pop_front()
+  )
 end
 
 -- called every frame, with constant delta time
@@ -54,8 +52,6 @@ function game_tick()
       duck.SeekFeed:connect(duck_seek_feed)
       duck.index = i
     end
-    print(ducks[1].AteFeed._connections)
-    print(ducks[2].AteFeed._connections)
 
   end
 

data/scripts/types/list.lua

@@ -68,16 +68,23 @@ function List:pop()
   return table.remove(self, #self)
 end
 
----Reduce.
----@param f function called with element, accumulator, index
----@param init any initial value of accumulator
+---Removes the first element in the list and returns it.
 ---@return any
+function List:pop_front()
+  return table.remove(self, 1)
+end
+
+---Reduce.
+---@generic T
+---@param f fun(element: any, accumulator: T, index: integer): T
+---@param init T|nil initial value of accumulator
+---@return T
 function List:reduce(f, init)
   return reduce(self, f, init)
 end
 
 ---Returns a new List of all elements of this list that match the predicate function.
----@param predicate function called with element
+---@param predicate fun(element: any): boolean
 ---@return List
 function List:filter(predicate)
   return filter(self, predicate)
@@ -126,4 +133,33 @@ function List:is_empty()
   return #self == 0
 end
 
+---Returns a (shallow) copy of this list.
+---@return List
+function List:copy()
+  return List.create(self)
+end
+
+---Returns a new copy of this list with the order of the elements shuffled around.
+---@return List
+function List:shuffled()
+  -- https://gist.github.com/Uradamus/10323382
+  local list = self:copy()
+  
+  for i = #list, 2, -1 do
+    local j = math.random(i)
+    list[i], list[j] = list[j], list[i]
+  end
+  
+  return list
+end
+
+---Returns a sorted copy of this list.
+---@param f? fun(a: any, b: any)
+---@return List
+function List:sorted(f)
+  local list = self:copy()
+  table.sort(list, f)
+  return list
+end
+
 return List