カリー化とインターフェイス

Applyable.java

// TVar -> TResult
interface Applyable<TVar, TResult> {
    public abstract TResult apply(TVar variable);
}

Program.java

class Program {
    public static void main(String[] args) {
        // 一旦別の関数的なものに受けて、部品チックに
        Applyable<String, Boolean> find_s = (new StringFinder()).apply("s");
        System.out.println(find_s.apply("sunotora"));   //=> true
        System.out.println(find_s.apply("gab_km"));     //=> false
        
        // 即時に適用
        System.out.println((new StringFinder()).apply("m").apply("sunotora"));  //=> false
        System.out.println((new StringFinder()).apply("m").apply("gab_km"));    //=> true
    }
}

StringFinder.java

// String -> String -> Boolean
class StringFinder implements Applyable<String, Applyable<String, Boolean>> {
    @Override
    public Applyable<String, Boolean> apply(String target) {
        final String variable = target;
        // String -> Boolean
        return new Applyable<String, Boolean>() {
            public Boolean apply(String value) {
                return value.contains(variable);
            }
        };
    }
}