Add immutable ordered finite 'map' and 'set' to the stdlib (#561)

I've been sitting on this code for almost ~~9~~ _13_ months now (started
on Xmas 2023), it's about time we finalise it.
This PR adds immutable ordered maps and sets based on weight balanced
trees into the standard library.

The `map` and `set` now work on all main backends: JS, LLVM, Chez.

Progress ~~is **blocked**~~ was blocked on:
1. ~~very annoying inliner bug(s?) [#733]~~ _resolved_ 🥳 
2. ~~missing comparisons on strings on LLVM [#748]~~ _resolved_ 🎉

Author: jiribenes

examples/stdlib/map/cache.check

@@ -0,0 +1,7 @@
+Get key1: value1
+Get key2: value2
+Get key1: newValue1
+Get key2: value2
+After cleaning:
+Get key1: newValue1
+Get key2: Not found

examples/stdlib/map/cache.effekt

@@ -0,0 +1,50 @@
+import map
+import bytearray
+
+record CacheEntry[V](value: V, timestamp: Int)
+
+effect time(): Int
+
+def main() = {
+  var currentTime = 0
+  try {
+    var cache: Map[String, CacheEntry[String]] = map::empty(compareStringBytes)
+    val maxAge = 8
+
+    def cachePut(key: String, value: String): Unit =
+      cache = cache.put(key, CacheEntry(value, do time()))
+
+    def cacheGet(key: String): Option[String] =
+      cache.get(key) match {
+        case Some(entry) and do time() - entry.timestamp < maxAge => Some(entry.value)
+        case _ => None()
+      }
+
+    def cleanExpiredEntries(): Unit = {
+      val currentTime = do time()
+      cache = cache.filter { (_, entry) =>
+        currentTime - entry.timestamp < maxAge
+      }
+    }
+
+    cachePut("key1", "value1")
+    cachePut("key2", "value2")
+
+    println("Get key1: " ++ cacheGet("key1").getOrElse { "Not found" })
+    println("Get key2: " ++ cacheGet("key2").getOrElse { "Not found" })
+
+    cachePut("key1", "newValue1")
+
+    println("Get key1: " ++ cacheGet("key1").getOrElse { "Not found" })
+    println("Get key2: " ++ cacheGet("key2").getOrElse { "Not found" })
+
+    cleanExpiredEntries()
+
+    println("After cleaning:")
+    println("Get key1: " ++ cacheGet("key1").getOrElse { "Not found" })
+    println("Get key2: " ++ cacheGet("key2").getOrElse { "Not found" })
+  } with time {
+    currentTime = currentTime + 1
+    resume(currentTime)
+  }
+}

examples/stdlib/map/counter.check

@@ -0,0 +1,7 @@
+ask: 3
+can: 3
+you: 3
+see: 0
+do: 4
+Effekt: 2
+[Effekt → 2, and → 1, ask → 3, but → 1, can → 3, do → 4, fellow → 2, for → 4, language → 2, man → 1, my → 2, not → 2, of → 2, programmers → 2, programs → 1, so → 1, the → 2, together → 1, we → 1, what → 4, will → 1, world → 1, you → 3, your → 2]

examples/stdlib/map/counter.effekt

@@ -0,0 +1,40 @@
+import map
+import bytearray
+
+def counter(words: List[String]): Map[String, Int] = {
+  var m: Map[String, Int] = map::empty(compareStringBytes);
+
+  list::foreach(words) { word =>
+    m = m.putWithKey(word, 1) { (_, n1, n2) => n1 + n2 }
+  }
+
+  m
+}
+
+def main() = {
+  // John F. Kennedy's Inaugural Address, Jan 20, 1961; modified for Effekt
+  val speech: List[String] = [
+    "and", "so", "my", "fellow", "Effekt", "programmers",
+    "ask", "not", "what", "your", "language", "can", "do", "for", "you",
+    "ask", "what", "you", "can", "do", "for", "your", "language",
+    "my", "fellow", "programmers", "of", "the", "world",
+    "ask", "not", "what", "Effekt", "will", "do", "for", "you",
+    "but", "what", "together", "we", "can", "do", "for", "the", "programs", "of", "man"
+  ]
+
+  val ctr: Map[String, Int] = counter(speech)
+
+  def test(word: String) = {
+    val count = ctr.getOrElse(word) { 0 }
+    println(word ++ ": " ++ count.show)
+  }
+
+  test("ask")
+  test("can")
+  test("you")
+  test("see")
+  test("do")
+  test("Effekt")
+
+  println(map::internal::prettyPairs(ctr.toList) { s => show(s) } { n => show(n) })
+}

examples/stdlib/map/map.check

@@ -0,0 +1,7 @@
+[0 → Hello, 1 → World, 2 → Woo!]
+[-1 → Hullo, 0 → Hello, 1 → World, 2 → Woo!]
+[-10 → EY, -1 → Hullo, 0 → Hello, 1 → World, 2 → Woo!]
+[0 → Hello, 2 → Woo!, 42 → Whole new world!, 100 → Big, 1000 → Bigger, 10000 → Biggest!]
+[-1 → Huh?!, 0 → Hello, 1 → Foo, 2 → Woo!, 42 → Whole new world!, 100 → Big, 1000 → Bigger, 10000 → Biggest!]
+[-1 → Huh?!, 0 → Hello, 1 → Foo, 2 → Woo!, 42 → Whole new world!, 100 → Big, 1000 → Bigger, 10000 → Biggest!]
+[0 → Hello, 1 → World, 2 → Woo!]

examples/stdlib/map/map.effekt

@@ -0,0 +1,28 @@
+import map
+
+def main() = {
+    val l = [(0, "Hello"), (1, "World"), (2, "Woo!")]
+
+    val m = map::fromList(l, compareInt)
+    println(map::internal::prettyPairs(m.toList) { n => show(n) } { s => show(s) })
+
+    val m2 = m.put(-1, "Hullo")
+    println(map::internal::prettyPairs(m2.toList) { n => show(n) } { s => show(s) })
+
+    val m3 = m2.put(-10, "EY")
+    println(map::internal::prettyPairs(m3.toList) { n => show(n) } { s => show(s) })
+
+    // ...
+
+    val m4 = m.delete(1).put(42, "Whole new world!").put(100, "Big").put(1000, "Bigger").put(10000, "Biggest!")
+    println(map::internal::prettyPairs(m4.toList) { n => show(n) } { s => show(s) })
+
+    val m5 = map::fromList(Cons((1, "Foo"), Cons((-1, "Huh?!"), m4.toList.reverse)), compareInt)
+    println(map::internal::prettyPairs(m5.toList) { n => show(n) } { s => show(s) })
+
+    val m6: Map[Int, String] = m5.toList.fromList(compareInt)
+    println(map::internal::prettyPairs(m6.toList) { n => show(n) } { s => show(s) })
+
+    val nuMap = map::fromList(l.reverse, compareInt)
+    println(map::internal::prettyPairs(nuMap.toList) { n => show(n) } { s => show(s) })
+}

examples/stdlib/map/minmax.check

@@ -0,0 +1,2 @@
+Min: 5 -> Five
+Max: 30 -> Thirty

examples/stdlib/map/minmax.effekt

@@ -0,0 +1,16 @@
+import map
+
+def show(opt: Option[(Int, String)]): String = opt match {
+  case Some((k, v)) => k.show ++ " -> " ++ v
+  case None() => "X"
+}
+
+def main() = {
+  val m = map::fromList([(10, "Ten"), (20, "Twenty"), (5, "Five"), (30, "Thirty")], compareInt)
+
+  val min: Option[(Int, String)] = m.getMin
+  val max: Option[(Int, String)] = m.getMax
+
+  println("Min: " ++ min.show)
+  println("Max: " ++ max.show)
+}

examples/stdlib/map/setops.check

@@ -0,0 +1,8 @@
+Union (keeping first value):
+[1 → apple, 2 → banana, 3 → cherry, 4 → elderberry]
+
+Union (combining values):
+[1 → apple, 2 → banana/berry, 3 → cherry/date, 4 → elderberry]
+
+Intersection (combining keys):
+[2 → banana-berry, 3 → cherry-date]

examples/stdlib/map/setops.effekt

@@ -0,0 +1,20 @@
+import map
+
+def main() = {
+  // Create multiple maps
+  val map1 = map::fromList([(1, "apple"), (2, "banana"), (3, "cherry")], compareInt)
+  val map2 = map::fromList([(2, "berry"), (3, "date"), (4, "elderberry")], compareInt)
+
+  // Test union with different combine strategies
+  println("Union (keeping first value):")
+  println(map::internal::prettyPairs(map1.union(map2).toList) { n => show(n) } { s => show(s) })
+
+  println("\nUnion (combining values):")
+  val combinedMap = map1.union(map2, compareInt) { (k, v1, v2) => v1 ++ "/" ++ v2 }
+  println(map::internal::prettyPairs(combinedMap.toList) { n => show(n) } { s => show(s) })
+
+  // Test intersection
+  println("\nIntersection (combining keys):")
+  val intersectedMap = map1.intersection(map2, compareInt) { (k, v1, v2) => v1 ++ "-" ++ v2 }
+  println(map::internal::prettyPairs(intersectedMap.toList) { n => show(n) } { s => show(s) })
+}