On Aug 27, 2014, at 11:12 AM, Matthias Felleisen <[email protected]> wrote:
> > On Aug 27, 2014, at 12:22 PM, Kevin Forchione <[email protected]> wrote: > >> >> #lang racket >> >> (provide (contract-out [foo >> (-> string? list?)]) >> (rename-out (foo bar))) >> >> (define (foo n) (list n)) >> >> (module+ test >> (require (submod "..")) >> (foo 3) >> (bar "3”)) >> >> Here foo violates the contract. Changing the argument to foo to “3” and >> the argument to bar to 3 shows that bar does not violate the contract. So >> the contract is bound to foo and not to the rename. Quite interesting! >> > > > contract-out attaches a contract to foo so when you can call foo on 3, you > get an error. > > provide also exports foo as bar w/o contract, so you can call it on anything > you want. > > This is clearly what the words of the program imply, and the semantics of the > language gives it to you. No problems! Yes, I agree. Very useful! Is there a way to attach a contract to a renamed identifier? I tried wrapping contract around a rename form and it didn’t appear to like it. -Kevin
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