-;;; Old comment, probably no longer applicable:
-;;;
-;;; ### Note: we give up early to keep from dropping lots of
-;;; information on the floor by returning overly general types.
+;;; Binding *APPROXIMATE-NUMERIC-UNIONS* to T allows merging non-adjacent
+;;; numeric types, eg (OR (INTEGER 0 12) (INTEGER 20 128)) => (INTEGER 0 128),
+;;; the compiler does this occasionally during type-derivation to avoid
+;;; creating absurdly complex unions of numeric types.
+(defvar *approximate-numeric-unions* nil)
+