> Is there anything that would prevent me from having to wrap functions in > make-parameter calls? Something like Clojure's binding special form (if > you're familiar with it).
I'm not a Clojure expert so please correct me if I'm wrong but it seems like you have to jump through similar hoops in Clojure? Clojure 1.3.0 user=> (defn add1 [x] (+ x 1)) #'user/add1 user=> (add1 10) 11 user=> (binding [add1 #(+ % 2)] (add1 10)) IllegalStateException Can't dynamically bind non-dynamic var: user/add1 clojure.lang.Var.pushThreadBindings (Var.java:339) user=> (defn ^:dynamic add1 [x] (+ x 1)) #'user/add1 user=> (add1 10) 11 user=> (binding [add1 #(+ % 2)] (add1 10)) 12 From the docs (http://clojure.org/vars): bindings created with binding can be assigned to, which provides a means for a nested context to communicate with code before it on the call stack. This capability is opt-in only by setting a metadata tag :dynamic to true as in the code block above On Sat, Dec 22, 2012 at 4:23 AM, Cristian Esquivias <cristian.esquiv...@gmail.com> wrote: > Is this the general practice? It looks rather cumbersome and difficult to > plan for. > > > - Cristian > > On Dec 21, 2012 6:45 PM, "David Van Horn" <dvanh...@ccs.neu.edu> wrote: >> >> On 12/21/12 9:41 PM, Cristian Esquivias wrote: >>> >>> I'm trying to replace a function with another using parameterize. >>> >>> For example, when I try: >>> >>> (define (add2 n) >>> (add1 (add1 n))) >>> >>> (parameterize ([add1 (λ [n] (+ n 2))]) >>> (add2 2)) >>> >>> I get an error: >>> >>> parameterize: contract violation >>> expected: parameter? >>> received: #<procedure:add1> >>> >>> How do I re-bind functions in Racket? >> >> >> You can only use parameterize with names bound to parameter values. Here's >> an example: >> >> #lang racket >> (define padd1 (make-parameter add1)) >> >> ((padd1) 4) >> >> (parameterize ([padd1 (λ (n) (+ 2 n))]) >> ((padd1) 4)) >> >> David >> >> > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users > ____________________ Racket Users list: http://lists.racket-lang.org/users
