FWIW: I believe the style guide suggests that 'cond' should be used instead of 'if' when a clause requires more than one expression. The newer Racket versions of 'cond' also permit internal defines. 'Begin' is unnecessary.
rac On Mar 21, 2012, at 3:37 PM, Joe Gilray wrote: > Hi Rodolfo, > > In this case though, printf will never return #f so "and" is equivalent to > "begin", right? > > -Joe > > > > On Wed, Mar 21, 2012 at 2:30 PM, Rodolfo Carvalho <rhcarva...@gmail.com> > wrote: > On Wed, Mar 21, 2012 at 17:21, Joe Gilray <jgil...@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: > http://en.wikipedia.org/wiki/Short-circuit_evaluation > > HTH, > > Rodolfo > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users
____________________ Racket Users list: http://lists.racket-lang.org/users
