(scheme case-lambda)(case-lambda <clause1> ...) syntaxEach clause is of the form (<formals> <body>), where <formals> and
<body> have the same syntax as in a lambda expression.
A case-lambda expression evaluates to a procedure that accepts a
variable number of arguments and is lexically scoped in the same
manner as a procedure resulting from a lambda expression. When the
procedure is called, the first clause for which the arguments agree
with <formals> is selected, where agreement is specified as for the
<formals> of a lambda expression. The variables of <formals> are
bound to fresh locations, the values of the arguments are stored in
those locations, the <body> is evaluated in the extended
environment, and the results of <body> are returned as the results
of the procedure call.
It is an error for the arguments not to agree with the <formals> of
any clause`.
Example:
(define add1
(case-lambda
((a) (add1 a 0))
((a b) (+ 1 a b))))
(add1 1) ;; => 2
(add1 1 2) ;; => 4