horse, horsegen: redesign approach for koka

horse/game-id.kk

@@ -0,0 +1,49 @@
+module horse/game-id
+
+// Game ID for characters, cards, skills, races, &c.
+// Values for different categories may overlap.
+alias game-id = int
+
+// Specific game ID types.
+// I've already made mistakes with ID categories and I haven't even committed this file yet.
+
+// Game ID for characters.
+// Generally numbers in the range 1000-9999.
+pub struct character-id
+  game-id: game-id
+
+// Game ID for trainees, i.e. costume instances of characters.
+// Generally a character ID with two digits appended.
+pub struct trainee-id
+  game-id: game-id
+
+// Game ID for skills.
+pub struct skill-id
+  game-id: game-id
+
+// Game ID for skill groups.
+pub struct skill-group-id
+  game-id: game-id
+
+// Game ID for skill icons.
+pub struct skill-icon-id
+  game-id: game-id
+
+// order2 comparison between any game ID types.
+pub inline fun order2(x: a, y: a, ?a/game-id: (a) -> game-id): order2<a>
+  match x.game-id.cmp(y.game-id)
+    Lt -> Lt2(x, y)
+    Eq -> Eq2(x)
+    Gt -> Gt2(x, y)
+
+// Comparison between any game ID types.
+pub inline fun cmp(x: a, y: a, ?a/game-id: (a) -> game-id): order
+  x.game-id.cmp(y.game-id)
+
+// Equality between any game ID types.
+pub inline fun (==)(x: a, y: a, ?a/game-id: (a) -> game-id): bool
+  x.game-id == y.game-id
+
+// Check whether a game ID is valid, i.e. nonzero.
+pub inline fun is-valid(x: a, ?a/game-id: (a) -> game-id): bool
+  x.game-id != 0