[racket] Cond function with test-expr = then-body works but is it wise?

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Fri May 24 12:13:27 EDT 2013


    [testing => values]

work for you? That returns the value of the testing expression w/o evaluating it twice. 

On May 24, 2013, at 12:08 PM, Don Green wrote:

> It is possible to create a cond test-expr that also serves as the then-body, however, this means that the expression would be executed twice.
> This seems to be ill advised in principle.
> Question: If it is ill-advised to create a cond test-expression that also serves as the then body, then what function is recommend?
> I am aware of the (cdr (or ... form.
> I am aware of the cond ... test-expr => proc-expr] form option.
> Thanks
> Don Green
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