[racket] (if ...) form without an else

From: Joe Gilray (jgilray at gmail.com)
Date: Wed Apr 11 23:51:47 EDT 2012

Hi Lothar,

The if statement in Racket always requires three arguments:

 test-expr then-expr else-expr)

if you only want a "then-expression", use "when" or "unless"
if you want more expressions, use "cond",  cond is a powerful and compact
construct in Racket


On Wed, Apr 11, 2012 at 11:42 AM, lothar atheling <lothar_ at warpmail.net>wrote:

> usually an (if ...) form without an else part does not cause an error.
> but sometimes it does, as the following shows:
> if: bad syntax (must have an "else" expression) in: (if isinitialised
> (expose))
> why the different behavior?
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