Re: Polymorphic functions in Clojure (or how to stop thinking in objects)...

Hi, I wanted to take the opportunity to thank the people who responded to my question on thinking beyond O-O. The replies form a very useful slice through Clojure design strategies and idiomatic use of the language. Thanks! Stu -- You received this message because you are subscribed to the Go

Re: Polymorphic functions in Clojure (or how to stop thinking in objects)...

On Tue, Mar 15, 2011 at 12:58 PM, Armando Blancas wrote: > Another choice is to construct shapes as closures with auto-dispatch. > So a circle could be made thus, with no data structure per se: > > (defn make-circle [x y r] >  (fn [method] >    (case method >      :draw (fn [color] ...) >      :ro

Re: Polymorphic functions in Clojure (or how to stop thinking in objects)...

On Mon, Mar 14, 2011 at 11:15 PM, Daniel Solano Gomez wrote: > This method works fairly well, and you can even use it to define > protocols for types you don't control, such as classes from a Java API. > > If you need some more complicated form of dispatch for polymorphism, > there is the multimet

Re: Polymorphic functions in Clojure (or how to stop thinking in objects)...

On Mar 15, 10:50 am, Mark Engelberg wrote: > On Tue, Mar 15, 2011 at 10:40 AM, Alan wrote: > > Seconded. I often know ahead of time I'll want to extend to > > multimethods eventually, but sometimes I don't. Because multimethods, > > protocols, and plain-old-functions look the same to the caller,

Re: Polymorphic functions in Clojure (or how to stop thinking in objects)...

On Tue, Mar 15, 2011 at 10:40 AM, Alan wrote: > Seconded. I often know ahead of time I'll want to extend to > multimethods eventually, but sometimes I don't. Because multimethods, > protocols, and plain-old-functions look the same to the caller, you > can write your code whatever way is most stra

Re: Polymorphic functions in Clojure (or how to stop thinking in objects)...

On Mar 15, 10:30 am, Daniel Solano Gomez wrote: > In the end, the it all depends on what fits best with what you are > doing.  One approach is to simply avoid using multimethods or > polymorphism as you start developing.  Instead, you can use a custom > dispatch using if or cond in your polymorphi

Re: Polymorphic functions in Clojure (or how to stop thinking in objects)...

Hi stu, take a look in clojure protocols. I think that this can help you. http://clojure.org/protocols Luiz Costa On Mon, Mar 14, 2011 at 11:54 PM, stu wrote: > Hi, > > I'd like to create a simple library of drawable shapes: lines,

Re: Polymorphic functions in Clojure (or how to stop thinking in objects)...

On Tue Mar 15 09:21 2011, Alan wrote: > On Mar 14, 8:15 pm, Daniel Solano Gomez wrote: > > I believe there are two approaches to doing this in Clojure: > > > > 1. Multimethods:http://clojure.org/multimethods > > 2. Protocols:http://clojure.org/Protocols > > > > Of the two, as of Clojure 1.2, proto

Re: Polymorphic functions in Clojure (or how to stop thinking in objects)...

On Mar 14, 7:54 pm, stu wrote: > Hi, > > I'd like to create a simple library of drawable shapes: lines, circles > and rectangles.  I've placed each type of shape in its own namespace > with functions that operate on that shape kind: > > (ns myshapes.line) > > (defn line ... creates new line ...) >

Re: Polymorphic functions in Clojure (or how to stop thinking in objects)...

Wow, it's like I'm reading Let Over Lambda all over again :) On Mar 15, 9:58 am, Armando Blancas wrote: > Another choice is to construct shapes as closures with auto-dispatch. > So a circle could be made thus, with no data structure per se: > > (defn make-circle [x y r] >   (fn [method] >     (ca

Re: Polymorphic functions in Clojure (or how to stop thinking in objects)...

Another choice is to construct shapes as closures with auto-dispatch. So a circle could be made thus, with no data structure per se: (defn make-circle [x y r] (fn [method] (case method :draw (fn [color] ...) :rotate (fn [degrees] ...) :r (fn [] r) :x (fn [] x) :

Re: Polymorphic functions in Clojure (or how to stop thinking in objects)...

On Mar 14, 8:15 pm, Daniel Solano Gomez wrote: > I believe there are two approaches to doing this in Clojure: > > 1. Multimethods:http://clojure.org/multimethods > 2. Protocols:http://clojure.org/Protocols > > Of the two, as of Clojure 1.2, protocols are the preferred way of doing > things.   Wha

Re: Polymorphic functions in Clojure (or how to stop thinking in objects)...

If the set of types is closed and will not be extended by users, there's nothing wrong with just writing your own dispatch using cond, something like: (defn draw [shape] (cond (triangle? shape) (draw-triangle shape) (circle? shape) (draw-circle shape) ...)) Then just write your

Re: Polymorphic functions in Clojure (or how to stop thinking in objects)...

On Mon Mar 14 19:54 2011, stu wrote: > The problem I have is with the myshapes.picture/draw function. As a > Clojure newb I keep wanting to think of this like a polymorphic > function in the O-O world that relies on each sequence member having a > draw function. > > What's the idiomatic way of han

Polymorphic functions in Clojure (or how to stop thinking in objects)...

Hi, I'd like to create a simple library of drawable shapes: lines, circles and rectangles. I've placed each type of shape in its own namespace with functions that operate on that shape kind: (ns myshapes.line) (defn line ... creates new line ...) (defn draw ... draws a line ...) To keep thin