tag:blogger.com,1999:blog-84298132732588578202011-08-02T18:24:46.411-04:00Sean McEligotSean McEligothttp://www.blogger.com/profile/15815160869147788296noreply@blogger.comBlogger11100tag:blogger.com,1999:blog-8429813273258857820.post-81689077605310677612010-08-14T23:12:00.005-04:002010-08-15T11:56:34.570-04:00Monads in Upcoming Java 7<span style="font-style:italic;">Under Construction</span><br />
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<script type="syntaxhighlighter" class="brush: java"><![CDATA[
public class Monad<T> {
public final T t;
public Monad(T t) {
this.t = t;
}
public String toString() {
return "Monad("+t+")";
}
public abstract static class Fun1<a,b> {
public abstract b apply(a a);
}
public abstract static class Fun2<a,b,c> {
public Fun1 curry(final a a) {
final Fun2 fun2 = this;
return #(b) { return fun2.apply(a,b);};
}
public abstract c apply(a a, b b);
}
public static <T> Monad<T> mreturn(final T t) {
return new Monad(t);
}
// (m t)->(t->m u)->(m u)
public static <T,U> Monad<U> mbind(final Monad<T> mt, Fun1<T,Monad<U>> tmu) {
return tmu.apply(mt.t);
}
public static Monad mdo(Monad m, Fun1... ff) {
Monad n = m;
for(Fun1 f: ff) {
n = mbind(n, f);
}
return n;
}
public static void main(String[] args) {
Monad.Fun1<Integer,Monad<Integer>> minc = #(x){ return new Monad(new Integer(x+1));};
Monad.Fun2<Integer,Integer,Monad<Float>> mdiv = #(a,b){ return new Monad(new Float(a.floatValue()/b));};
Monad m = new Monad(1);
Monad<Float> o = Monad.mdo(
m, // 1
minc, // 2
minc, // 3
minc, // 4
mdiv.curry(2) // 0.5
);
System.out.println(o); // 0.5
}
}
]]></script><div class="blogger-post-footer"><img width='1' height='1' src='https://blogger.googleusercontent.com/tracker/8429813273258857820-8168907760531067761?l=seanmceligot.blogspot.com' alt='' /></div>Sean McEligothttp://www.blogger.com/profile/15815160869147788296noreply@blogger.com0