/*
 *  Copyright (c) 1999-2003, Gene Cooperman; Rights to copy and distribute
 *  for non-commercial purposes only are freely granted, but only as
 *  long as this copyright statement remains.  No warranty is implied.
 */

import java.io.*;

public class SchemeInterpreter {
    public static void main(String[] args)
	    throws IOException, ClassNotFoundException {
	SchemeFunction.initBuiltInFunctions();
	//mytest();

	// THE read-eval-print LOOP MUST BE INSERTED HERE.
	BufferedReader in
	    = new BufferedReader(new InputStreamReader(System.in));
	SchemeReader reader = new SchemeReader( in );
	while (true) {
	    try {
		System.out.print("> ");
		System.out.println( reader.nextExpression().eval() );
	    } catch (SchemeError e) {
		e.printStackTrace();
	    }
        }
    }

  private static final void mytest() throws IOException {
    SchemeObject x = new Fixnum(3);
    System.out.println(x.eval());
    SchemeReader sr;
    sr = new SchemeReader( new StringReader("'3") );
    sr = new SchemeReader( new StringReader("'(+ 3 4)") );
    System.out.println( sr.nextExpression().eval() );
    sr = new SchemeReader( new StringReader("(+ 3 4)") );
    System.out.println( sr.nextExpression().eval() );
    sr = new SchemeReader( new StringReader("()") );
    System.out.println( sr.nextExpression().eval() );
    sr = new SchemeReader( new StringReader("(set! x 3)") );
    System.out.println( sr.nextExpression().eval() );
    sr = new SchemeReader( new StringReader("#t") );
    System.out.println( sr.nextExpression().eval() );
    sr = new SchemeReader( new StringReader("((lambda (x) x) 5)") );
    System.out.println( sr.nextExpression().eval() );
    sr = new SchemeReader( // inner lambda captures binding of x; lex. closure
	new StringReader("((lambda (x) (lambda (y) (+ y x))) 2)") );
    System.out.println( sr.nextExpression().eval() );
    sr = new SchemeReader( // inner lambda does not captures binding of x
	new StringReader("((lambda (a) a) (lambda (x) (+ x 1)))") );
    System.out.println( sr.nextExpression().eval() );
    sr = new SchemeReader( // Test shadowing
	new StringReader("((lambda (x) (lambda (x) (+ x 1))) 5)") );
    System.out.println( sr.nextExpression().eval() );
    sr = new SchemeReader(new StringReader( // x in inner lambda can be set
	"(set! foo (lambda (x) (set! bar (lambda () x)) (set! x 3) bar))" +
	"(if (= ((foo 1)) 3) 'correct 'wrong)") );
    System.out.println( sr.nextExpression().eval() );
    System.out.println( sr.nextExpression().eval() );;
    sr = new SchemeReader( // Test standard Currying
	new StringReader("(((lambda (x) (lambda (y) (+ y x))) 2) 3)") );
    System.out.println( sr.nextExpression().eval() );
    sr = new SchemeReader(new StringReader(
	   "(define fact" +
	   "  (lambda (g)" +
	   "     (lambda (n)" +
	   "       (if (= n 0) 1 (* n (g (- n 1)))))))" +
	   "(define Y" +
	   "  (lambda (f)" +
	   "    ((lambda (x) (f (lambda (y) 'first ((x x) y))))" +
	   "     (lambda (x) (f (lambda (y) 'second ((x x) y)))))))" +

	   "((Y fact) 2)" +
	   "((Y fact) 4)" +
	   "(if (= ((Y fact) 4) 24) 'correct 'wrong)") );
    // System.out.println( sr.nextExpression().eval() );
    // System.out.println( sr.nextExpression().eval() );
    // System.out.println( sr.nextExpression().eval() );
    // System.out.println( sr.nextExpression().eval() );
    // System.out.println( sr.nextExpression().eval() );
  }
    static ObArray obArray = ObArray.getInstance();
}

// SchemeError will be caught in the read-eval-print loop, but not before.
class SchemeError extends Error {
  SchemeError() { super(); }
  SchemeError(String str) { super(str); }
}