University
of Washington • CSE583 • D. Notkin © 2000
25
A note about binding and parameter passing
lAll variables refer
to data values, yielding a simple, regular
model
llet binding and parameter passing do not copy
–They introduce a new name that refers to and shares the right-hand-side value
–“call by pointer value” or “call by sharing”
l(define
snork ‘(3 4 5))
(define (f fork)
(let ((dork fork))
(and (eqv? snork fork)
(eqv? dork fork))))
(f snork) ® #t
(define (f fork)
(let ((dork fork))
(and (eqv? snork fork)
(eqv? dork fork))))
(f snork) ® #t