When I do something like
Code: (define (conv3 x y z) (
(+ (+ (* x 1) (* y 10)) (* z 100))))
and then invoke it with
Code: (conv3 1 2 3)
I get the error
Code: Backtrace:
In standard input:
43: 0* [conv3 1 2 3]
41: 1 [321]
standard input:41:23: In expression ((+ # #)):
standard input:41:23: Wrong type to apply: 321
ABORT: (misc-error)
Of course, when I substitute the variables in like
Code: (+ (+ (* 1 1) (* 2 10)) (* 3 100))
I get the desired response, 321.
EDIT: nevermind; there was an extra set of parentheses.
Glad you found your error
Also, I'm against the special syntax for defining, not that it really matters. I think
Code: (define conv3
(lambda (x y z)
(+ (+ (* x 1) (* y 10) (* z 100)))))
looks a lot cleaner, and emphasizes that functions aren't any different from regular numbers/values/cells. Also, if you're going to do a lot of Scheme, I would recommend either: a) using Emacs with some Scheme mode, b) getting a different editor that can help balance your parentheses, or c) tabbing out your code. Any of those would help with coding (And, (a) actually does (b) and (c) for you 
). Just my two cents 
_player1537 wrote:
Glad you found your error :) Also, I'm against the special syntax for defining, not that it really matters. I think
Code: (define conv3
(lambda (x y z)
(+ (+ (* x 1) (* y 10) (* z 100)))))
looks a lot cleaner, and emphasizes that functions aren't any different from regular numbers/values/cells. Also, if you're going to do a lot of Scheme, I would recommend either: a) using Emacs with some Scheme mode, b) getting a different editor that can help balance your parentheses, or c) tabbing out your code. Any of those would help with coding (And, (a) actually does (b) and (c) for you ;)). Just my two cents :P
eeeeeewww, emacs (Has /usr/bin/emacs been moved to /bin/shells yet?)
Anyway, I've found another conundrum:
Code: guile> (define (interest amount)
(cond
[(<= amount 1000) .04]
[(<= amount 5000) .045]
[(> amount 5000) .05])
)
guile> (interest 4000)
yields
Code: Backtrace:
In standard input:
197: 0* [interest 4000]
192: 1 (cond [ (<= amount 1000) ...)
standard input:192:1: In procedure memoization in expression (cond [ (<= amount 1000) ...):
standard input:192:1: In file "standard input", line 191: Bad cond clause [ in expression (cond [ (<= amount 1000) .04] [ (<= amount 5000) .045] [ (> amount 5000) .05]).
ABORT: (syntax-error)
I'm not sure where this came from, as it was copied straight from the text I was using... (http://www.htdp.org/2003-09-26/Book/curriculum-Z-H-7.html)
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