On Oct 25, 2011, at 11:52 AM, Dan Grossman wrote: > Hi all, > > I'm wondering if there's a concise, informal, mostly complete list of > R5RSisms that won't work in Racket (#lang racket). As I'm porting > some old teaching materials to Racket, I've come across: > > * Cannot write (if e1 e2); replace with (when e1 e2) or (and e1 e2) > * Cannot write (); replace with null or '() > * Cannot write set-car! or set-cdr! > > To be clear, I like all these changes, it would just be great to have > a check-list of things to look for. > > Honestly, what would most help /me/ personally would be a list > comparing to "Pretty Big" from May 2008, but since that would > presumably help fewer people, R5RS seems like a better starting point. > I can probably figure out other non-R5RS changes relevant to me, such > as struct being preferred to define-struct and significant changes to > the module system. > > And notice I'm not asking for things Racket has /added/ -- that list > would be long and is well covered by reading the documentation.
Is there an R5RS test suite lying around? This would seem to be a relatively efficient way to compute such a list. Okay, Hmm... There's a "corner cases" test that I found, wherein Racket differs (according to the test suite) from R5RS in the semantics of letrec (I've attached these tests below). There's also a monster 62,000 line test suite called s7test.scm that is a test of a scheme implementation called s7, apparently derived from a whole bunch of other tests living in other places. I spent 10 minutes shuffling through the lexical differences before running out of steam. So! Here's my incomplete list; anyone that wants can add to it; I'm guessing that the list would be an extremely long one.... In module context: - re-definition of identifier not allowed - if must have else - semantics of letrec arguably non-standard - many reader extensions (#| comment style, two infix dots) - set-car! and set-cdr! replaced by set-mcar! and set-mcdr! ;;Credits to Al Petrofsky ;; In thread: ;; defines in letrec body ;; http://groups.google.com/groups?selm=87bsoq0wfk.fsf%40app.dial.idiom.com (should-be 1.1 0 (let ((cont #f)) (letrec ((x (call-with-current-continuation (lambda (c) (set! cont c) 0))) (y (call-with-current-continuation (lambda (c) (set! cont c) 0)))) (if cont (let ((c cont)) (set! cont #f) (set! x 1) (set! y 1) (c 0)) (+ x y))))) ;;Credits to Al Petrofsky ;; In thread: ;; Widespread bug (arguably) in letrec when an initializer returns twice ;; http://groups.google.com/groups?selm=87d793aacz.fsf_-_%40app.dial.idiom.com (should-be 1.2 #t (letrec ((x (call/cc list)) (y (call/cc list))) (cond ((procedure? x) (x (pair? y))) ((procedure? y) (y (pair? x)))) (let ((x (car x)) (y (car y))) (and (call/cc x) (call/cc y) (call/cc x))))) John
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