nmcb · nmcb · Feb 10, 2026 · Feb 10, 2026
diff --git a/2015/src/main/scala/aoc2015/Day03.scala b/2015/src/main/scala/aoc2015/Day03.scala
@@ -1,7 +1,7 @@
 package aoc2015
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 
 object Day03 extends AoC:
 

diff --git a/2015/src/main/scala/aoc2015/Day11.scala b/2015/src/main/scala/aoc2015/Day11.scala
@@ -31,6 +31,8 @@ object Day11 extends AoC:
       case Zero extends Carry(0x00)
       case One  extends Carry(value = 0x01)
 
+    given CanEqual[Carry, Carry] = CanEqual.derived
+
     val MinValue: Char   = 'a'
     val MaxValue: Char   = 'z'
     val ValueRange: Char = (MaxValue - MinValue + 1).toChar

diff --git a/2015/src/main/scala/aoc2015/Day12.scala b/2015/src/main/scala/aoc2015/Day12.scala
@@ -39,6 +39,8 @@ object Day12 extends AoC:
   case class Num(underlying: Long)             extends Json
   case class Arr(underlying: List[Json])       extends Json
   case class Obj(underlying: Map[String,Json]) extends Json
+
+  given CanEqual[Json, Json] = CanEqual.derived
 
   def solve(json: Json, objValueFilter: Json => Boolean = _ => true): Long =
     def loop(acc: Long, json: Json): Long =

diff --git a/2015/src/main/scala/aoc2015/Day21.scala b/2015/src/main/scala/aoc2015/Day21.scala
@@ -9,7 +9,7 @@ object Day21 extends AoC:
   object Player:
     def equip(points: Int, weapon: Weapon, armor: Option[Armor], rings: Seq[Ring]): Player =
       assert(rings.size <= 2, "max 2 rings")
-      assert(rings == rings.distinct, "max one of a kind")
+      assert((rings diff rings.distinct).isEmpty, "max one of a kind")
       Player( points = points
             , damage = weapon.damage + rings.map(_.damage).sum
             , armor  = armor.map(_.armor).getOrElse(0) + rings.map(_.armor).sum
@@ -41,6 +41,8 @@ object Day21 extends AoC:
   enum Outcome:
     case Won
     case Lost
+
+  given CanEqual[Outcome, Outcome] = CanEqual.derived    
 
   case class Game(player: Player, boss: Player):
     import Outcome.*
@@ -67,7 +69,7 @@ object Day21 extends AoC:
       w  <- Weapon.values.toList
       a  <- Armor.values.toList.map(Option(_)) :+ Option.empty[Armor]
       rs <- Ring.values.toList.map(List(_)) ++ Ring.values.toList.combinations(2) ++ List(List.empty[Ring])
-      if rs == rs.distinct
+      if (rs diff rs.distinct).isEmpty
     yield
       Player.equip(100, w, a, rs)
 

diff --git a/2015/src/main/scala/aoc2015/Day22.scala b/2015/src/main/scala/aoc2015/Day22.scala
@@ -12,6 +12,8 @@ object Day22 extends AoC:
     case Recharge     extends Spell(229, 5)
 
   import Spell.*
+
+  given CanEqual[Spell, Spell] = CanEqual.derived
 
   val Spells = Set(MagicMissile, Drain, Shield, Poison, Recharge)
 

diff --git a/2016/src/main/scala/aoc2016/Day01.scala b/2016/src/main/scala/aoc2016/Day01.scala
@@ -1,7 +1,7 @@
 package aoc2016
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 import scala.annotation.tailrec
 import scala.util.Try
 

diff --git a/2016/src/main/scala/aoc2016/Day10.scala b/2016/src/main/scala/aoc2016/Day10.scala
@@ -1,6 +1,8 @@
 package aoc2016
 
 import nmcb.*
+
+import scala.CanEqual.derived
 import scala.collection.mutable
 
 object Day10 extends AoC:
@@ -10,6 +12,8 @@ object Day10 extends AoC:
     case Out(override val index: Int) extends Target(index)
 
   import Target.*
+
+  given CanEqual[Target, Target] = CanEqual.derived
 
   enum Inst:
     case Init(bot: Bot, value: Int)

diff --git a/2016/src/main/scala/aoc2016/Day13.scala b/2016/src/main/scala/aoc2016/Day13.scala
@@ -1,7 +1,7 @@
 package aoc2016
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 
 import scala.collection.*
 import scala.collection.immutable.Map

diff --git a/2016/src/main/scala/aoc2016/Day17.scala b/2016/src/main/scala/aoc2016/Day17.scala
@@ -2,7 +2,7 @@ package aoc2016
 
 import nmcb.*
 import nmcb.predef.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 
 import java.security.MessageDigest
 import scala.collection.*

diff --git a/2016/src/main/scala/aoc2016/Day22.scala b/2016/src/main/scala/aoc2016/Day22.scala
@@ -1,7 +1,7 @@
 package aoc2016
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 
 object Day22 extends AoC:
 
@@ -16,6 +16,8 @@ object Day22 extends AoC:
       else if isMassive then '#'
       else                   '.'
 
+  given CanEqual[Node, Node] = CanEqual.derived
+
   val nodes: Map[Pos,Node] =
     lines
       .filter(_.startsWith("/dev/grid/node"))
@@ -24,7 +26,7 @@ object Day22 extends AoC:
         Pos.of(x, y) -> Node(used, avail)
       .toMap
 
-  def viable(nodes: Map[Pos,Node]): Vector[(Node,Node)] =
+  def viable(nodes: Map[Pos, Node]): Vector[(Node, Node)] =
     for
       (_,a) <- nodes.toVector
       (_,b) <- nodes.toVector

diff --git a/2016/src/main/scala/aoc2016/Day24.scala b/2016/src/main/scala/aoc2016/Day24.scala
@@ -1,7 +1,7 @@
 package aoc2016
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 
 object Day24 extends AoC:
 

diff --git a/2017/src/main/scala/aoc2017/Day03.scala b/2017/src/main/scala/aoc2017/Day03.scala
@@ -1,7 +1,7 @@
 package aoc2017
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 import nmcb.predef.*
 
 import scala.annotation.tailrec

diff --git a/2017/src/main/scala/aoc2017/Day06.scala b/2017/src/main/scala/aoc2017/Day06.scala
@@ -41,6 +41,8 @@ object Day06 extends AoC:
           loop(next, seen :+ current)
       loop(this)
 
+  given CanEqual[Area, Area] = CanEqual.derived
+
   override lazy val answer1: Int =
     Area(banks).redistribute.size - 1
 

diff --git a/2017/src/main/scala/aoc2017/Day11.scala b/2017/src/main/scala/aoc2017/Day11.scala
@@ -14,6 +14,8 @@ object Day11 extends AoC:
     case NW
 
   import Dir.*
+
+  given CanEqual[Dir, Dir] = CanEqual.derived
 
   case class Hex(x: Int, y: Int, z: Int):
     assert(x + y + z == 0)

diff --git a/2017/src/main/scala/aoc2017/Day14.scala b/2017/src/main/scala/aoc2017/Day14.scala
@@ -1,7 +1,7 @@
 package aoc2017
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 
 import Day10.KnotHash
 import Day12.Dijkstra

diff --git a/2017/src/main/scala/aoc2017/Day19.scala b/2017/src/main/scala/aoc2017/Day19.scala
@@ -1,7 +1,7 @@
 package aoc2017
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 
 import scala.annotation.tailrec
 

diff --git a/2017/src/main/scala/aoc2017/Day22.scala b/2017/src/main/scala/aoc2017/Day22.scala
@@ -1,7 +1,7 @@
 package aoc2017
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 import nmcb.predef.*
 
 object Day22 extends AoC:
@@ -10,6 +10,8 @@ object Day22 extends AoC:
     case Clean, Infected, Weakened, Flagged
 
   import Status.*
+
+  given CanEqual[Status, Status] = CanEqual.derived
 
   case class Carrier(nodes: Map[Pos,Status], current: Pos, dir: Dir, infected: Int = 0):
 

diff --git a/2017/src/main/scala/aoc2017/Day25.scala b/2017/src/main/scala/aoc2017/Day25.scala
@@ -9,6 +9,8 @@ object Day25 extends AoC:
     case L, R
 
   import Move.*
+
+  given CanEqual[Move, Move] = CanEqual.derived
 
   type State       = String
   type Value       = Int

diff --git a/2017/src/test/scala/aoc2017/Test2017.scala b/2017/src/test/scala/aoc2017/Test2017.scala
@@ -3,6 +3,8 @@ package aoc2017
 import org.scalatest.funsuite.AnyFunSuite
 
 class Test2017 extends AnyFunSuite:
+
+  given CanEqual[Any, Any] = CanEqual.derived
 
   test("Day 1: Inverse Captcha"):
     assertResult(1069)(Day01.answer1)

diff --git a/2018/src/main/scala/aoc2018/Day02.scala b/2018/src/main/scala/aoc2018/Day02.scala
@@ -18,6 +18,9 @@ object Day02 extends AoC:
       idLettersWith(3) >= 1
 
   object Box:
+
+    given CanEqual[Box, Box] = CanEqual.derived
+
     val IdCharSet: String = "abcdefghijklmnopqrstuvwxyz"
     def fromString(id: String): Box = Box(id)
 

diff --git a/2018/src/main/scala/aoc2018/Day03.scala b/2018/src/main/scala/aoc2018/Day03.scala
@@ -1,7 +1,7 @@
 package aoc2018
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 
 object Day03 extends AoC:
 

diff --git a/2018/src/main/scala/aoc2018/Day04.scala b/2018/src/main/scala/aoc2018/Day04.scala
@@ -12,6 +12,8 @@ object Day04 extends AoC:
 
   import Event.*
 
+  given CanEqual[Event, Event] = CanEqual.derived
+
   type Timestamp = String
 
   case class Record(timestamp: Timestamp, event: Event):

diff --git a/2018/src/main/scala/aoc2018/Day06.scala b/2018/src/main/scala/aoc2018/Day06.scala
@@ -1,7 +1,7 @@
 package aoc2018
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 
 import scala.collection.+:
 import scala.collection.immutable.Vector

diff --git a/2018/src/main/scala/aoc2018/Day10.scala b/2018/src/main/scala/aoc2018/Day10.scala
@@ -1,7 +1,7 @@
 package aoc2018
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 
 import scala.annotation.*
 import scala.math.Integral.Implicits.*

diff --git a/2018/src/main/scala/aoc2018/Day11.scala b/2018/src/main/scala/aoc2018/Day11.scala
@@ -1,7 +1,7 @@
 package aoc2018
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 
 import scala.collection.*
 

diff --git a/2018/src/main/scala/aoc2018/Day13.scala b/2018/src/main/scala/aoc2018/Day13.scala
@@ -50,6 +50,8 @@ object Day13 extends AoC:
         case Straight => Right
         case Right    => Left
 
+  given CanEqual[Turn, Turn] = CanEqual.derived
+
   case class Cart(pos: Pos, dir: Dir, atIntersection: Turn = Turn.Left):
 
     def move(grid: Grid): Cart =

diff --git a/2018/src/main/scala/aoc2018/Day15.scala b/2018/src/main/scala/aoc2018/Day15.scala
@@ -1,7 +1,7 @@
 package aoc2018
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 
 import scala.annotation.tailrec
 import scala.util.Try
@@ -22,10 +22,13 @@ object Day15 extends AoC:
 
   import FighterType.*
 
+  given CanEqual[FighterType, FighterType] = CanEqual.derived
+
   case class Fighter(fighterType: FighterType, pos: Pos, hitPoints: Int = 200, attackPower: Int = 3)
 
-  given Ordering[Pos]     = Ordering.by(_.toTuple.swap)
-  given Ordering[Fighter] = Ordering.by(_.pos)
+  given Ordering[Pos]              = Ordering.by(_.toTuple.swap)
+  given Ordering[Fighter]          = Ordering.by(_.pos)
+  given CanEqual[Fighter, Fighter] = CanEqual.derived
 
   def targetsOf(fighter: Fighter)(using fighters: List[Fighter]): Set[Fighter] =
     fighters.filter(_.fighterType == fighter.fighterType.target).toSet

diff --git a/2018/src/main/scala/aoc2018/Day16.scala b/2018/src/main/scala/aoc2018/Day16.scala
@@ -63,6 +63,8 @@ object Day16 extends AoC:
         case EQRI => mem.setRI(a, b, c, (a: Int) => (b: Int) => if a == b then 1 else 0)
         case EQRR => mem.setRR(a, b, c, (a: Int) => (b: Int) => if a == b then 1 else 0)
 
+  given CanEqual[Inst, Inst] = CanEqual.derived
+
   type Test  = (Mem, Codes, Mem)
 
   extension (test: Test)

diff --git a/2018/src/main/scala/aoc2018/Day17.scala b/2018/src/main/scala/aoc2018/Day17.scala
@@ -1,7 +1,7 @@
 package aoc2018
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 
 object Day17 extends AoC:
 
@@ -16,6 +16,8 @@ object Day17 extends AoC:
     case Stopped
     case Flowing
 
+  given CanEqual[Stream, Stream] = CanEqual.derived
+
   import Stream.*
 
   import Iterator.*

diff --git a/2018/src/main/scala/aoc2018/Day18.scala b/2018/src/main/scala/aoc2018/Day18.scala
@@ -1,7 +1,7 @@
 package aoc2018
 
 import nmcb.*
-import nmcb.pos.*
+import nmcb.pos.{*, given}
 import nmcb.predef.*
 
 import scala.collection.*

diff --git a/2018/src/main/scala/aoc2018/Day22.scala b/2018/src/main/scala/aoc2018/Day22.scala
@@ -12,6 +12,8 @@ object Day22 extends AoC:
     case Wet    extends RegionType(1)
     case Narrow extends RegionType(2)
 
+  given CanEqual[RegionType, RegionType] = CanEqual.derived
+
   case class Region(x: Int, y: Int):
     infix def +(x: Int, y: Int): Region    = copy(x = this.x + x, y = this.y + y)
     infix def manhattan(that: Region): Int = (x - that.x).abs + (y - that.y).abs
@@ -23,6 +25,8 @@ object Day22 extends AoC:
 
 
   object Region:
+
+    given CanEqual[Region, Region] = CanEqual.derived
 
     val depth: Int     = 11817
     val mouth: Region  = Region(0, 0)
@@ -55,6 +59,8 @@ object Day22 extends AoC:
     case Torch
     case ClimbingGear
 
+  given CanEqual[Tool, Tool] = CanEqual.derived
+
   import RegionType.*
   import Tool.*
 

diff --git a/2018/src/main/scala/aoc2018/Day23.scala b/2018/src/main/scala/aoc2018/Day23.scala
@@ -14,6 +14,8 @@ object Day23 extends AoC:
     infix def hasOverlappingRadiusWith(that: Bot): Boolean =
       loc.manhattan(that.loc) <= radius + that.radius
 
+  given CanEqual[Bot, Bot] = CanEqual.derived
+
   val bots: Set[Bot] =
     lines
       .collect:

diff --git a/2018/src/main/scala/aoc2018/Day24.scala b/2018/src/main/scala/aoc2018/Day24.scala
@@ -13,6 +13,8 @@ object Day24 extends AoC:
     case Infection
 
   import Army.*
+
+  given CanEqual[Army, Army] = CanEqual.derived
 
   type AttackKind = String