Chez Scheme Transcript [Thu Mar  8 14:59:43 2012]
> (load "abs.ss")
> (add 3 4)
7
> (math 6 9 +)
15
> (math 6 9 *)
54
> 6
6
> +
#<procedure +>
> *
#<procedure *>
> (lambda (x) x)
#<procedure>
> (lambda (x) y)
#<procedure>
> (define foo (lambda (x) x))
> foo
#<procedure foo>
> (+ 3 4)
7
> (foo 3)
3
> ((lambda (x) x) 3)
3
> (define a 3)
> a
3
> foo
#<procedure foo>
> (a 3)

Error: attempt to apply non-procedure 3.
Type (debug) to enter the debugger.

> (define id
    (lambda (x) x))
> id
#<procedure id>
> (+ 3 4)
7
> (id 4)
4
> ((lambda (x) x) 4)
4
> (define foo (lambda (x) (lambda (x) x)))
> foo
#<procedure foo>
> (foo 3)
#<procedure>
> ((foo 3) 4)
4
> ((lambda (x) x) (lambda (x) x))
#<procedure>
> (((lambda (x) x) (lambda (x) x)) 3)
3
> (define add-generator (lambda (n) (lambda (m) (+ n m))))
> add-generator
#<procedure add-generator>
> (define foo (add-generator 3))
> foo
#<procedure>
> (define add3 (add-generator 3))
> (define add42 (add-generator 42))
> (add3 7)
10
> (add42 10)
52
> (transcript-off)