Since my ears are ringing, I'll chime in. There's a few things to separate out here:
1) Symbolic math 2) Term rewriting 3) Staged computation Mathematica can provide all three to varying degrees. Espresso targets symbolic mathematics. Kovas' work is about term rewriting as a computational paradigm. Clojure offers limited, but practically proven facilities for staged computation in the form of eval, macros, etc. My guess is that you can accomplish whatever specific DSL task you're after with traditional functional approaches and get acceptable performance. Seeing as you're new to Clojure, I suggest you try to go down that road first. When you have a particular use case to discuss and some experience solving the problem with traditional techniques, we can discuss opportunities for more sophisticated approaches. However, if you're really after #3, you're probably out of luck in the short term. Longer term, I indent to experiment with this stuff in the context of https://github.com/brandonbloom/eclj Cheers, Brandon On Monday, June 16, 2014 1:25:40 PM UTC-4, kovasb wrote: > > So I've thought about this quite a bit (as have some other people, > like Brandon Bloom), and started working on a library a while back > exploring some ideas https://github.com/kovasb/term > > The main idea of term is to take any expression and turn unbound > symbols into datatypes that satisfy mathematica-like properties. > > for instance > > (head (term (a 1 2 3))) -> a > (let [x (term a)] (head (x 1 2 3))) -> a > (term (map a [1 2 3])) -> ((a 1) (a 2) (a 3)) > > > This works pretty well, but to be truly useful you also need a > standard library of transformation rules that will for instance > implement + with combinations of symbols and concrete values, and of > course an evaluator. > > Based on my experiments it is quite possible to create a term > rewriting evaluator that matches Mathematica's speed (see > https://github.com/kovasb/combinator) > > The main question is how such a system deals with clojure > interoperability. Ultimately the transformation rules must bottom out > in clojure, and their results will eventually be consumed by clojure, > so getting that right will largely determine the usability of the > system. > > > > > > > > > > > > On Mon, Jun 16, 2014 at 7:57 AM, Dilvan <dil...@gmail.com <javascript:>> > wrote: > > Hi, > > > > Thanks for both answers. I will try to find the relevant text in Joy > of > > Clojure (I have access to the first edition). > > I followed the expresso link, but I am not interested in mathematical > > expressions. > > Refining my question: I am more interested in the programming aspects > of > > Mathematica (or to its descendant Wolfram Language). In the eval case, a > > better example would be (a is unbound): > > > > (def b 1) > > (eval-partial '(+ (+ 8 2) a (* 9 (+ 2 b)))) > > --> '(+ 37 a) > > > > Eval-partial would return a Lisp expression with unbound symbols. > > The expression being evaluated could be quite complex. > > With eval-partial, I would like to be able to have complex functions > that > > depend on results that aren't ready yet. They would evaluate (partially) > to > > expressions that could be re-evaluated later, to see if all the symbols > they > > depend upon are ready (bound). I intend to use this technique to write > more > > flexible DSLs. > > > > BTW, if expresso can do some similar to this, I am willing to give it > a > > second look. > > > > Any ideas? > > > > Cheers, > > > > Dilvan. > > > > > > On Friday, June 13, 2014 6:46:56 PM UTC-3, Dilvan wrote: > >> > >> Hi all, > >> > >> I'm a novice to Clojure (but not to programming). > >> I'm looking for an implementation of an eval function to eval > >> expression like Mathematica does. > >> For instance, in Mathematica the expression: > >> > >> 8 + a + 9 (2 + b) + 2 > >> > >> if a and b are not bound, translates to > >> > >> Plus[10, a, Times[9, Plus[2, b]]] > >> > >> if a and b become bounded later (let say to 1 and 2) and the > expression > >> is evaluated again, it returns 47. > >> > >> I would like to be able to run: > >> (eval-partial '(+ (+ 8 2) a (* 9 (+ 2 b)))) > >> and get, if a and b are unbound: > >> (fn [x y] (+ 10 x (* 9 (+ 2 y)))) > >> or (better still) > >> ['(a b) (fn [x y] (+ 10 x (* 9 (+ 2 y))))] > >> Notice that, whenever possible, the eval takes place and parts of > the > >> expression are evaluated (in the example above, the expression (+ 8 2) > is > >> evaluated to 10). > >> > >> If you know of any implementation or have any ideas on the subject, > >> please let me know. > >> > >> Cheers, > >> Dilvan. > >> > > > > -- > > You received this message because you are subscribed to the Google > > Groups "Clojure" group. > > To post to this group, send email to clo...@googlegroups.com > <javascript:> > > Note that posts from new members are moderated - please be patient with > your > > first post. > > To unsubscribe from this group, send email to > > clojure+u...@googlegroups.com <javascript:> > > For more options, visit this group at > > http://groups.google.com/group/clojure?hl=en > > --- > > You received this message because you are subscribed to the Google > Groups > > "Clojure" group. > > To unsubscribe from this group and stop receiving emails from it, send > an > > email to clojure+u...@googlegroups.com <javascript:>. > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Clojure" group. 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