On 4/17/20, Sorawee Porncharoenwase <sorawee.pw...@gmail.com> wrote: >> >> My understanding is that contract-out only provides protection against >> inappropriate calls from clients *outside* the module, whereas >> define/contract enforces the contract against everyone, including things >> inside the module. Do I have that right? >> > > I think that's correct. Note though that the implication is that > define/contract could produce a much more expensive code, especially for > recursive function, since it will need to check against the contract for > every iteration. > > >> On a related topic, I don't understand the concept of positive and >> negative blame. Can someone fill me in? >> > > I always forget which is positive and negative, so I won't use the terms > here (and too lazy to lookup). But roughly, suppose you attach a function > contract (-> number? string?) to a function value, then there are mainly > two ways things could go wrong. > > 1. Client uses the function incorrectly by calling it with non-number. > 2. The function itself returns a non-string. > > A blame would indicate whose party is at fault when a contract is > violated--caller or the function itself.
1 = negative = the client that uses the value 2 = positive = the code that made the value But unless you're using `contract` directly, you don't need to know these words to benefit from contracts. -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/CAFUu9R5vabY64_HZRWv1zNoyuEd7K5p8i8jfVN0JB1reufYEPw%40mail.gmail.com.
