On 9/17/12 7:11 PM, Jon Zeppieri wrote:
The fact that the first one works at all should probably be considered a
bug. The syntax of case here:
http://docs.racket-lang.org/reference/case.html?q=case#(form._((lib._racket/private/more-scheme..rkt)._case))
dictates that the constants in a case clause be parenthesized.
But they *are* parenthesized... after the reader expands '.
That's why you can do weird things like ((lambda 'x ''''''x) add1 0).
David
The more important issue, however, is that the constants are implicitly
quoted by the case form. So, when you explicitly quote them, they're
double quoted. You're trying to match 'a against ''a.
-Jon
On Mon, Sep 17, 2012 at 6:47 PM, Kieron Hardy <kieron.ha...@gmail.com
<mailto:kieron.ha...@gmail.com>> wrote:
Hi all,
Can anyone explain why the first function below selects 'x1-case as
expected but the second fails to select 'x2-case? Am I expecting
something to happen that shouldn't?
Thanks,
Kieron.
****
#lang racket
(case 'a
['a 'x1-case]
['b 'x1-case]
[(15 2 3) 'y1-case]
[(10 11 12) 'z1-case])
(case 'a
[('a 'b) 'x2-case]
[(15 2 3) 'y2-case]
[(10 11 12) 'z2-case])
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