# [racket] Printing multiple stmts in cond

nikhil wrote at 04/30/2011 03:16 AM:
>* In my case, I have an incoming function which takes 4 arguments and I
*>* need to generate a function which takes in 5 args when a
*>* condition satisfies, if not then the original 4 args .
*
From looking at the example you provided, two ways come to mind
immediately. Either way is fine. Which you use depends on the
circumstances, including code maintainability.
#lang racket
(define (f? x)
;; This is just a placeholder for "f?".
#t)
(define (condition?)
;; This is just a placeholder for "condition?".
(zero? (random 2)))
;; This uses ",@" splicing.
(define (parse-func-1 exp)
(let ((x1 'x1) (x2 'x2) (x3 'x3) (x4 'x4))
(cond
[(f? exp)
`(FF
,x1
,x2
,@(if (condition?)
'(xNEW)
'())
,x3
,x4)])))
;; This moves the "if" higher up.
(define (parse-func-2 exp)
(let ((x1 'x1) (x2 'x2) (x3 'x3) (x4 'x4))
(cond
[(f? exp)
(if (condition?)
`(FF
,x1
,x2
xNEW
,x3
,x4)
`(FF
,x1
,x2
,x3
,x4))])))
--
http://www.neilvandyke.org/