In addition to the standard #open and #close directives, Caml Light provides three additional directives.
+. The notation
prefixid can be used to refer to the identifier id itself. Expressions of the form expr1 id expr2 are parsed as the application
prefixid expr1 expr2. The argument to the
#infixdirective must be an identifier, that is, a sequence of letters, digits and underscores starting with a letter; otherwise, the
#infixdeclaration has no effect. Example:
#infix "union";; let prefix union = fun x y -> ... ;; [1,2] union [3,4];;