Index: main.d
==================================================================
--- main.d
+++ main.d
@@ -3,16 +3,70 @@
  * License: NYSL 0.9982 (http://www.kmonos.net/nysl/
  *
  * Entry point for Polemy interpreter.
  */
 
-import std.stdio;
+import std.stdio;
+import std.algorithm;
+import polemy.value;
+import polemy.lex;
+import polemy.parse;
+import polemy.ast;
+import polemy.eval;
 
-version(unittest) static ~this()
+class REPL
 {
-	writeln( "(Press Enter to finish)" );
-	readln();
+	Table ctx;
+	string buf;
+	Value  lastVal;
+	int lineno = 1;
+	int nextlineno = 1;
+	this() { ctx = createGlobalContext(); }
+
+	bool tryRun( string s )
+	{
+		nextlineno ++;
+		buf ~= s;
+		try {
+			AST a = parseString(buf, "<REPL>", lineno);
+			buf = "";
+			lineno = nextlineno;
+			lastVal = eval(a, ctx);
+		} catch( LexException ) {
+			// always EOF exception, so wait next
+			return false;
+		} catch( ParseException e ) {
+			if( find(e.msg, "EOF") ) // ultra ad-hoc
+				return false;
+			throw e;
+		}
+		return true;
+	}
+
+	bool singleInteraction()
+	{
+		writef(">> ", lineno);
+		string line = readln();
+		if( line.startsWith("exit") || line.startsWith("quit") )
+			return false;
+		try {
+			if( tryRun(line) )
+				writeln(lastVal);
+		} catch(Throwable e) {
+			writeln(e);
+		}
+		return true;
+	}
 }
 
 void main( string[] args )
 {
+	if( args.length <= 1 )
+	{
+		writeln("Welcome to Polemy 0.1.0");
+		for(auto r = new REPL; r.singleInteraction();) {}
+	}
+	else
+	{
+		evalFile(args[1]);
+	}
 }

Index: polemy/eval.d
==================================================================
--- polemy/eval.d
+++ polemy/eval.d
@@ -88,11 +88,11 @@
 Tuple!(Value,"val",Table,"ctx") evalString(S,T...)(S str, T fn_ln_cn)
 {
 	return eval( polemy.parse.parseString(str, fn_ln_cn) );
 }
 
-Tuple!(Value,"val",Table,"ctx") evalFile(S, T...)(S filenae, T ln_cn)
+Tuple!(Value,"val",Table,"ctx") evalFile(S, T...)(S filename, T ln_cn)
 {
 	return eval( polemy.parse.parseFile(filename, ln_cn) );
 }
 
 Tuple!(Value,"val",Table,"ctx") eval(AST e)

Index: polemy/lex.d
==================================================================
--- polemy/lex.d
+++ polemy/lex.d
@@ -13,12 +13,12 @@
 
 class LexException : Exception
 {
 	const LexPosition pos;
 
-	this( const LexPosition pos, string msg, string file="", int line=0 )
-		{ super(sprintf!"[%s] %s"(pos, msg), file, line); this.pos = pos; }
+	this( const LexPosition pos, string msg, string file="", int line=0, Throwable next=null )
+		{ super(sprintf!"[%s] %s"(pos, msg), file, line, next); this.pos = pos; }
 };
 
 /// Represents a position in a source code
 
 class LexPosition
@@ -36,23 +36,24 @@
 }
 
 unittest
 {
 	auto p = new LexPosition("hello.cpp", 123, 45);
-	auto q = new LexPosition("hello.cpp", 123, 46);
 
 	assert_eq( p.filename, "hello.cpp" );
 	assert_eq( p.lineno, 123 );
 	assert_eq( p.column, 45 );
 	assert_eq( to!string(p), "hello.cpp:123:45" );
-	assert_lt( p, q );
-	assert_ne( p, q );
 
 	assert( !__traits(compiles, new LexPosition) );
 	assert( !__traits(compiles, p.filename="foo") );
 	assert( !__traits(compiles, p.lineno  =789) );
 	assert( !__traits(compiles, p.column  =222) );
+
+	auto q = new LexPosition("hello.cpp", 123, 46);
+	assert_lt( p, q );
+	assert_ne( p, q );
 }
 
 /// Represents a lexer token
 
 class Token
@@ -159,11 +160,11 @@
 
 	string readQuoted(const LexPosition pos){char[] buf; return readQuoted(pos,buf);}
 	string readQuoted(const LexPosition pos, ref char[] buf)
 	{
 		if( reader.empty )
-			throw new LexException(pos, "EOF found while lexing a quoted-string");
+			throw genex!LexException(pos, "EOF found while lexing a quoted-string");
 		dchar c = reader.front;
 		reader.popFront;
 		if( c == '"' )
 			return assumeUnique(buf);
 		if( c == '\\' && !reader.empty ) {
@@ -225,10 +226,11 @@
 }
 
 unittest
 {
 	assert( std.range.isForwardRange!(Lexer) );
+	assert( is(ElementType!(Lexer) == Token) );
 }
 
 unittest
 {
 	auto lex = lexerFromString("this	is a \t\r\n pen :-( @@;  ");

Index: polemy/parse.d
==================================================================
--- polemy/parse.d
+++ polemy/parse.d
@@ -13,12 +13,12 @@
 
 class ParseException : Exception
 {
 	const LexPosition pos;
 
-	private this( const LexPosition pos, string msg )
-		{ super(sprintf!"%s [%s]"(msg, pos)); this.pos = pos; }
+	this( const LexPosition pos, string msg, string file="", int line=0, Throwable next=null )
+		{ super(sprintf!"[%s] %s"(pos, msg), file, line, next); this.pos = pos; }
 }
 
 private auto createException(Lexer)(Lexer lex, string msg)
 	{ return new ParseException(lex.empty?null:lex.front.pos, msg); }
 
@@ -25,11 +25,11 @@
 /// Entry points of this module
 
 auto parseString(S, T...)(S str, T fn_ln_cn)
 	{ return parserFromString(str, fn_ln_cn).parse(); }
 
-auto parseFile(S, T...)(S filename,T ln_cn)
+auto parseFile(S, T...)(S filename, T ln_cn)
 	{ return parserFromString(filename, ln_cn).parse(); }
 
 /// Named Constructor of Parser
 
 private auto parserFromLexer(Lexer)(Lexer lex)

Index: tricks/tricks.d
==================================================================
--- tricks/tricks.d
+++ tricks/tricks.d
@@ -19,12 +19,13 @@
 	return writer.data;
 }
 
 unittest
 {
-	assert( sprintf!"%s == %d"("1+2", 3)   == "1+2 == 3" );
-	assert( sprintf!"%s == %04d"("1+2", 3) == "1+2 == 0003" );
+	assert_eq( sprintf!"%s == %04d"("1+2", 3), "1+2 == 0003" );
+	assert_eq( sprintf!"%2$s == %1$s"("1+2", 5, 8), "5 == 1+2" );
+	assert_throw!Error( sprintf!"%s%s"(1) );
 }
 
 /// Create an exception with automatically completed filename and lineno information
 
 auto genex(ExceptionType, string fn=__FILE__, int ln=__LINE__, T...)(T params)