Fantastic, thanks for the clarification Ben. I'll start using it to see what it does, as I have a few functions that occasionally throw errors through contracts - which I should call 'blame' - yet I can't figure out much from it.
On Fri, Apr 17, 2020 at 6:09 PM Ben Greenman <[email protected]> wrote: > On 4/17/20, Sorawee Porncharoenwase <[email protected]> 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 a topic in the > Google Groups "Racket Users" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/racket-users/VA_ufNV6J24/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/racket-users/CAFUu9R5vabY64_HZRWv1zNoyuEd7K5p8i8jfVN0JB1reufYEPw%40mail.gmail.com > . > -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/CAD7_NO7Yo%2BL-T5JnxKB74-OPNce3On0YY%3DujHLR7L%2B1Ch%2Bqz1w%40mail.gmail.com.
