In Racket, accessors are functions and are thus perfectly legitimate arguments:
(define (foo some-posn some-accessor) (some-accessor some-posn)) > (foo my-posn posn-x) 3 On Sep 6, 2011, at 2:17 PM, Todd Bittner wrote: > Hi, > > I'm trying to something along the following lines: > > > (define-struct posn (x y)) > > (define my-posn (3 4)) > > (define (foo posn-instance field) > (posn-field posn-instance)) > > where calling > > (foo my-posn "x") > > would dynamically substitute posn-field with posn-x and the function would > return 3. > > I don't know what to do with either "x" or posn-field to get this to work. I > *think* I'm looking for something like a string->function function, where I > could pass in "x" and posn-field would be replaced by > > (string->function (string-append "posn-" field)) > > I just don't know if there's something that currently serves that purpose or, > if not, how to go about creating that function. > > Thanks, > > Todd > _________________________________________________ > For list-related administrative tasks: > http://lists.racket-lang.org/listinfo/users _________________________________________________ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/users
