[racket] Racket style question

From: Rodolfo Carvalho (rhcarvalho at gmail.com)
Date: Wed Mar 21 17:30:46 EDT 2012

On Wed, Mar 21, 2012 at 17:21, Joe Gilray <jgilray at gmail.com> wrote:

> Hi Tim,
> Thanks for sharing your code.
> Quick, newby question: why do you use "and" instead of "begin" in your
> progress function?

If you are used to run commands from bash you may do things like

command1 && command2 && command3

e.g.:  mkdir somedir && cd somedir && git clone ...

Why people do that? Simply put, all of the commands after a `&&' are only
run if the commands before executes fine (return code 0).
So "git clone" will be executed only if I could create a dir and cd to it.
It will not be executed if I don't have permissions to create a dir.

Using "and" is like using "&&" in bash, while "begin" is equivalent of
separating the commands with ";".

More on short-circuit evaluation:


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