Yes, except that the contracts are checked at each call of the procedure. So if (define (foo x) (values x x)) is contracted with (-> any/c any/c) an exception will be raised on the first call to foo, but not during compilation.

but in that case, foo must be supplied a single value argument, right ?

in what case do we use https://docs.racket-lang.org/reference/when_unless.html#%28form._%28%28lib._racket%2Fprivate%2Fletstx-scheme..rkt%29._when%29%29\|when vs https://docs.racket-lang.org/reference/if.html#%28form._%28%28quote._~23~25kernel%29._if%29%29\|if ?

If you try to call foo with more than one argument, a contract exception will be raise.

(when test body ...) is equivalent to (if test (begin body ...) (void)) So you should use when when you want to write an if like the above.

i don’t get it

It’s mostly useful when you want to conditionally execute some imperative code.

(when test (set! x something))

if understand, when is an if devoid of failure case?

yes

thanks,

@kokou.afidegnon See also https://stackoverflow.com/a/10863193/23567

thanks

I just installed a package from the main catalog. If I now want to work with the latest source from github instead, what is required? After making a change to the source, do I just raco pkg update and pass a flag to use my directory vs. the main catalog?

Hmm… simpler than I thought: raco pkg remove frog git clone <my fork> raco pkg install ~/my-dir

Should’ve just read the https://github.com/greghendershott/frog/blob/master/CONTRIBUTING.md\|CONTRIBUTING.md file :)

raco pkg update —clone frog, and then go to frog and do the appropriate git commands

That’s what I’d do