ckirkendall

(use '[clojure.core.match :only [match]])

(defn evaluate [env [sym x y]]
  (match [sym]
    ['Number]   x
    ['Add]      (+ (evaluate env x) (evaluate env y))
    ['Multiply] (* (evaluate env x) (evaluate env y))
    ['Variable] (env x)))
    
(def environment {"a" 3, "b" 4, "c" 5})

ckirkendall

The Objective

This language experiment was designed to show how parametric polymorphism and type classes are
implemented in different languages. The implementation languages where chosen out of personal
preference. I am well aware it's not complete and would love for you to help me with that.  If
you don't see your favorite language please add it as a comment.  I am also not an expert in all
of these languages but did try to make them as idiomatic as possible. If you believe there is a
better solution please leave a comment with the implementation.

The Code

ckirkendall

(defrecord Tree [left elm right])

(defprotocol Monoid
   (append [a b] )
   (identity [a] ))

(defprotocol Foldable
  (foldl [l f i])
  (mfirst [l]))
  

ckirkendall

{"nodes":[
  {"x":80, "r":40, "label":"Node 1"}, 
  {"x":200, "r":60, "label":"Node 2"}, 
  {"x":380, "r":80, "label":"Node 3"}
]}

ckirkendall

abstract class Show<A> {
  
  public static register(Class c, Show s){
     Map<Class,Object> shows=TypeClassFactory.tcs.get(Show.class)
     if(shows!=null){
       shows.put(c,s);
     }else{
       shows = new Map<Class,Object>();
       shows.put(c,s);
       TypeClassFactory.tcs.put(Show.class, shows);

ckirkendall

(ns workbench.enlive.predicate
  (:require
   [clojure.zip :as z]
   [workbench.enlive.engine
    :refer [compile-step]]
   [workbench.enlive.select
    :refer [zip-select]]))

;; ## Builtin predicates
;;

ckirkendall

;; The macros
;; most macros here alias names from select.cljs
;; they will get used in regular calls

(ns lib.select
  (:require
   [clojure.string :as str]))

;; selector syntax
(defn intersection [preds]

ckirkendall

(ns lambda-calc.core)

;; THIS MACRO CREATES A LAMBDA THAT IS COMPATABLE WITH LAMBDA AS DEFINED IN 
;; LAMBDA CALCULUS -> CURRIED NON-RECURSIVE 
(defmacro f* [args & body]
  (let [fsym (gensym "fn")
        alist (for [n (range 1 (count args))]
                (take n args))
        curries (map #(do `(~(vec %) (partial ~fsym ~@%))) alist)]
    `(fn ~fsym ~@curries (~args ~@body)))) 

ckirkendall

(defn & [f k]
  (fn [& args]
    (k (apply f args))))

(defmacro cps [steps]
  (if (seq steps)
    `(& ~(first steps)
        (cps ~(rest steps)))
    `identity))

ckirkendall

object P26 extends App {
  def combinations[T](n: Int, l: List[T]): List[List[T]] = {
    if(l.size < n) {
      Nil
    } else {
	  n match {
	    case 0 => Nil
	    case 1 => l.map{List(_)}
	    case _ => combinations(n-1,l.tail).map{ l.head :: _} ::: combinations(n, l.tail)
	  }