diff --git a/Cargo.toml b/Cargo.toml
index 5ee8a6d..1e18722 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -8,6 +8,6 @@ edition = "2021"
 [dependencies]
 regex = "*"
 lazy_static = "1.4.0"
-rand = "0.8.5"
+rand = "*"
 colored = "*"
 
diff --git a/prog.vsasm b/prog.vsasm
new file mode 100644
index 0000000..c385967
--- /dev/null
+++ b/prog.vsasm
@@ -0,0 +1,10 @@
+
+0xc8c7a99bb88e156b:
+	push int 0x2
+	push int 0x4
+	cmp eq int
+	jump-unless 0x6
+	push int 0x1
+	ret
+	push int 0x0
+	ret
diff --git a/src/conf/mod.rs b/src/conf/mod.rs
index 13ff46c..eb02ea8 100644
--- a/src/conf/mod.rs
+++ b/src/conf/mod.rs
@@ -1,31 +1,40 @@
 use crate::parser::data::Diagnostics;
 
+#[derive(Default)]
 pub struct Settings {
-    gen_erpn: bool
+    gen_erpn: bool,
+    gen_vsasm: bool,
 }
 
 impl Settings {
-    fn new() -> Self {
-        Settings {
-            gen_erpn: false
-        }
-    }
-
     pub fn gen_erpn(&self) -> bool {
         self.gen_erpn
     }
+
+    pub fn gen_vsasm(&self) -> bool {
+        self.gen_vsasm
+    }
 }
 
 pub fn parse_args(diagnostics: &mut Diagnostics) -> Settings {
     let args = std::env::args().collect::<Vec<String>>();
 
-    let mut settings = Settings::new();
+    let mut settings = Settings::default();
 
     for arg in args.iter() {
         match arg.as_str() {
             "--no-info" => diagnostics.set_loglvl(crate::parser::data::LogLvl::Warn),
             "--no-warn" => diagnostics.set_loglvl(crate::parser::data::LogLvl::Err),
             "--erpn" => settings.gen_erpn = true,
+            "--vsasm" => settings.gen_vsasm = true,
+            "-h" => println!(concat!(
+                "help:\n",
+                "--no-info: print only warning and errors\n",
+                "--no-warn: print only errors\n",
+               "--erpn: write a *.erpn (extended reverse polish notation) summary to disk\n",
+                "--vsasm: write a .vsasm (virtual simplified assembly language) summary to disk\n",
+                "-h: print this dialog"
+            )),
             _ => ()
         }
     }
diff --git a/src/inter/mod.rs b/src/inter/mod.rs
index 021a9f5..822b83d 100644
--- a/src/inter/mod.rs
+++ b/src/inter/mod.rs
@@ -35,5 +35,6 @@ pub fn convert_to_erpn<'a>(funcs: &mut Vec<Func<'a>>, declrs: &Vec<Declr<'a>>) {
 
         // write down function body
         write_expr(&mut file, &mut indent, func.expr.as_ref().unwrap());
+        writeln!(&mut file).unwrap();
     }
-}
\ No newline at end of file
+}
diff --git a/src/main.rs b/src/main.rs
index eb2e3f7..d836ba2 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -18,20 +18,20 @@ pub fn message<S>(typ: MessageType, msg: S)
 where
     S: Into<String>,
 {
-    println!("{}: {}", typ.to_colored(), msg.into().bold().bright_white());
+    println!("{}: {}\n", typ.to_colored(), msg.into().bold().bright_white());
 }
 
 fn main() {
     let source = r"
-
-foo(x:int) = int {
-    x / 2
-}
+-- structs are tables
 
 main() = int {
-    a = foo(4)
- 
-    a
+
+    unless 2 == 4 {
+        yield 1;
+    }
+    
+    yield 0;
 }
 ";
 
diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index fcdef03..db7fae7 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -324,13 +324,14 @@ fn discover_exprs<'a>(
                         }
                         expr = VecDeque::new();
                         blocks.push(Block::new());
+
                         continue;
                     }
                     '}' => {
                         // pop topmost block of the stack, storing it in the next lower block
                         if let Some(block) = blocks.pop() {
                             if let Some(dst) = blocks.last_mut() {
-                                dst.push_back(Expr::Block(block));
+                                dst.push_back(Expr::Block(block)); 
                             } else {
                                 diagnostics.set_err(&top, crate::msg::ERR41, "");
                                 return Err(());
@@ -346,7 +347,7 @@ fn discover_exprs<'a>(
                         }
 
                         continue;
-                    }
+                    },
                     _ => (),
                 },
                 _ => (),
@@ -356,7 +357,7 @@ fn discover_exprs<'a>(
         }
 
         if !expr.is_empty() {
-            if let Some(block) = blocks.last_mut() {
+            if let Some(block) = blocks.last_mut() {     
                 block.push_back(Expr::Term(expr));
             } else {
                 diagnostics.set_err(expr.back().unwrap(), crate::msg::ERR40, "");
@@ -613,7 +614,13 @@ fn parse_term<'a>(
             Token::Assign(_, _, _) => {
                 op_stack.push(token);
             }
-            Token::Keyword(_, _) => op_stack.push(token),
+            Token::Keyword(key, _) => {
+                match key {
+                    Keyword::Unless => (),
+                    _ => ()
+                }
+                op_stack.push(token)
+            },
 
             Token::Delemiter(char, _) => match char {
                 '(' => op_stack.push(token),
@@ -689,6 +696,7 @@ fn parse_term<'a>(
             }
             _ => (),
         }
+
     }
 
     while let Some(mut token) = op_stack.pop() {
diff --git a/src/token/mod.rs b/src/token/mod.rs
index 6bccd46..b0a9e4f 100644
--- a/src/token/mod.rs
+++ b/src/token/mod.rs
@@ -161,11 +161,10 @@ impl Operator {
         diagnostics: &mut crate::parser::data::Diagnostics,
     ) -> Result<(Option<Prim>, Option<Prim>),()> {
         for combination in types.iter() {
-            if let (result, hint) =
-                self.present_types(operands, combination.0, combination.1, dbginf, diagnostics)?
-            {
-                return Ok((result, hint));
-            }
+            let (result, hint) =
+                self.present_types(operands, combination.0, combination.1, dbginf, diagnostics)?;
+            
+            return Ok((result, hint));
         }
         Ok((None, None))
     }
@@ -500,7 +499,7 @@ pub enum Token<'a> {
     Keyword(Keyword, DebugInfo),
     Type(Prim, DebugInfo),
     /// Semicolon
-    Terminator(DebugInfo),
+    Terminator(DebugInfo)
 }
 
 impl<'a> std::fmt::Display for Token<'a> {
diff --git a/src/vmrt/mod.rs b/src/vmrt/mod.rs
index 91f5ae7..6cc680f 100644
--- a/src/vmrt/mod.rs
+++ b/src/vmrt/mod.rs
@@ -12,7 +12,17 @@ enum Data {
     Int(i64),
     Rat(f64),
     Bool(bool),
-    Off(u64),
+}
+
+impl std::fmt::Display for Data {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Data::Int(v) => f.write_fmt(format_args!("int {:#x}", v))?,
+            Data::Rat(v) => f.write_fmt(format_args!("float {}", v))?,
+            Data::Bool(v) => f.write_fmt(format_args!("bool {}", v))?
+        }
+        Ok(())
+    }
 }
 
 impl Data {
@@ -95,7 +105,7 @@ enum Instr {
     /// push the value stored at offset from the local stack onto the local stack
     Load(usize),
     /// store the value stored at the stack[0](offset) stack[1](value) onto the stack
-    Store,
+    Store(usize),
 
     Call(u64),
 
@@ -103,9 +113,67 @@ enum Instr {
 
     Operation(Operation),
 
+    Jump(usize),
+    JumpUnless(usize),
+
     Exit,
 }
 
+impl std::fmt::Display for Instr {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Instr::Pop => f.write_str("\tpop")?,
+            Instr::Exit => f.write_str("\texit")?,
+            Instr::Return => f.write_str("\tret")?,
+            Instr::Load(offset) => f.write_fmt(format_args!("\tload {:#x}", offset))?,
+            Instr::Push(value) => f.write_fmt(format_args!("\tpush {}", value))?,
+            Instr::Call(uuid) => f.write_fmt(format_args!("\tcall {:#x}", uuid))?,
+            Instr::Jump(offset) => f.write_fmt(format_args!("\tjump {:#x}", offset))?,
+            Instr::JumpUnless(offset) => f.write_fmt(format_args!("\tjump-unless {:#x}", offset))?,
+            Instr::Operation(op) => {
+                match op {
+                    Operation::Int(op) => match op {
+                        IntOp::Add => f.write_str("\tadd int")?,
+                        IntOp::Sub => f.write_str("\tsub int")?,
+                        IntOp::Mul => f.write_str("\tmul int")?,
+                        IntOp::Div => f.write_str("\tdiv int")?,
+
+                        IntOp::CmpEq => f.write_str("\tcmp eq int")?,
+                        IntOp::CmpNEq => f.write_str("\tcmp not-eq int")?,
+                        IntOp::CmpLt => f.write_str("\tcmp lt eq int")?,
+                        IntOp::CmpGt => f.write_str("\tcmp gt int")?,
+                        IntOp::CmpLtEq => f.write_str("\tcmp lt-eq int")?,
+                        IntOp::CmpGtEq => f.write_str("\tcmp gt-eq int")?,
+                    },
+                    Operation::Rat(op) => match op {
+                        RatOp::Add => f.write_str("\tadd float")?,
+                        RatOp::Sub => f.write_str("\tsub float")?,
+                        RatOp::Mul => f.write_str("\tmul float")?,
+                        RatOp::Div => f.write_str("\tdiv float")?,
+
+                        RatOp::CmpEq => f.write_str("\tcmp eq float")?,
+                        RatOp::CmpNEq => f.write_str("\tcmp not-eq float")?,
+                        RatOp::CmpLt => f.write_str("\tcmp lt eq float")?,
+                        RatOp::CmpGt => f.write_str("\tcmp gt float")?,
+                        RatOp::CmpLtEq => f.write_str("\tcmp lt-eq float")?,
+                        RatOp::CmpGtEq => f.write_str("\tcmp gt-eq float")?,
+                    },
+                    Operation::Bool(op) => match op {
+                        BoolOp::And => f.write_str("\tand")?,
+                        BoolOp::Or => f.write_str("\tor")?,
+                        BoolOp::Xor => f.write_str("\txor")?,
+
+                        BoolOp::CmpNEq => f.write_str("\tcmp not-eq bool")?,
+                        BoolOp::CmpEq => f.write_str("\tcmp eq bool")?,
+                    }
+                }
+            },
+            Instr::Store(offset) => f.write_fmt(format_args!("\tstore {:#x}", offset))?,
+        }
+        Ok(())
+    }
+}
+
 /// function stack layout
 /// +----------------------------------+
 /// | Parameter (0)                    |
@@ -130,9 +198,16 @@ pub struct Program {
     procs: HashMap<u64, Proc>,
 }
 
+enum LabelType {
+    Unless(usize),
+    Loop(usize),
+    Pad
+}
+
 #[derive(Default)]
 struct Compiletime<'a> {
     vartable: HashMap<&'a str, usize>,
+    labels: Vec<LabelType>,
     stacksize: usize,
 }
 
@@ -143,8 +218,9 @@ fn parse_term<'a>(
     ct: &mut Compiletime<'a>,
     code: &mut Vec<Instr>,
 ) -> Result<(), ()> {
+    
     for token in term.iter() {
-        let instr = match token {
+        match token {
             Token::Number(value, hint, _) => {
                 code.push(Instr::Push(match hint {
                     NumHint::Int => Data::Int(value.parse::<i64>().unwrap()),
@@ -158,12 +234,12 @@ fn parse_term<'a>(
             }
             Token::Arg(name, _) => {
                 let off = declr[x].get_arg_ord(name);
-
                 code.push(Instr::Load(off));
                 ct.stacksize += 1;
             }
             Token::Assign(name, _, _) => {
                 ct.vartable.insert(name.clone(), ct.stacksize - 1);
+                code.push(Instr::Store(ct.stacksize - 1));
             }
             Token::Var(name, _) => {
                 code.push(Instr::Load(*ct.vartable.get(name).unwrap()));
@@ -254,10 +330,13 @@ fn parse_term<'a>(
             Token::Keyword(keyword, _) => match keyword {
                 crate::token::Keyword::Yield | crate::token::Keyword::Return => {
                     code.push(Instr::Return)
+                },
+                crate::token::Keyword::Unless => {
+                    ct.labels.push(LabelType::Unless(code.len()));
+                    code.push(Instr::JumpUnless(0));
                 }
                 _ => (),
             },
-
             _ => (),
         };
     }
@@ -271,9 +350,24 @@ fn parse_block<'a>(
     ct: &mut Compiletime<'a>,
     prog: &mut Vec<Instr>,
 ) -> Result<(), ()> {
+
+    ct.labels.push(LabelType::Pad);
+
     for expr in block.iter() {
         compile_expr(expr, x, declr, ct, prog)?;
     }
+    // resolve JumpUnless Labels
+    ct.labels.pop();
+
+    if let Some(label) = ct.labels.pop() {
+        match label {
+            LabelType::Unless(line) => {
+                prog[line] = Instr::JumpUnless(prog.len());
+            },
+            _ => ()
+        }
+    }
+
     Ok(())
 }
 
@@ -320,7 +414,9 @@ pub fn compile<'a>(funcs: &Vec<Func<'a>>, declrs: &Vec<Declr<'a>>, settings: &cr
             .insert(declrs[x].uuid(), create_proc(&declrs[x], code));
     }
 
-     
+    if settings.gen_vsasm() {
+        output::dump_program(&prog);
+    } 
 
     Ok(prog)
 }
@@ -345,6 +441,14 @@ impl Runtimestack {
     pub fn peek(&mut self, index: usize) -> Data {
         self.stack[index]
     }
+
+    pub fn top(&self) -> &Data {
+        &self.stack[self.stack.len() - 1]
+    }
+
+    pub fn put(&mut self, offset: usize, value: Data)  {
+        self.stack[offset] = value;
+    }
 }
 
 fn call_fn(prog: &Program, proc: &Proc, superstack: &[Data]) -> Result<Option<Data>, ()> {
@@ -354,9 +458,10 @@ fn call_fn(prog: &Program, proc: &Proc, superstack: &[Data]) -> Result<Option<Da
     for i in 0..proc.args {
         stack.push(superstack[superstack.len() - i - 1].clone());
     }
-
-    for instr in proc.code.iter() {
-        match instr {
+    
+    let mut x = 0;
+    while x < proc.code.len() {
+        match &proc.code[x] {
             Instr::Pop => {
                 stack.pop();
             }
@@ -368,11 +473,28 @@ fn call_fn(prog: &Program, proc: &Proc, superstack: &[Data]) -> Result<Option<Da
                 let v = stack.peek(*offset);
                 stack.push(v);
             },
+            Instr::Store(offset) => {
+                let data = stack.top().clone();
+                stack.put(*offset, data);
+            },
             Instr::Call(addr) => {
                 if let Some(value) = call_fn(prog, prog.procs.get(addr).unwrap(), &stack.stack)? {
                     stack.push(value);
                 }
             },
+            Instr::Jump(addr) => {
+                x = *addr - 1;
+            },
+            Instr::JumpUnless(addr) => {
+                match stack.pop() {
+                    Some(Data::Bool(false)) => x = *addr - 1,
+                    Some(Data::Bool(true)) => (),
+                    _ => {
+                        crate::message(crate::token::MessageType::Critical, "no condition for unless on stack");
+                        panic!();
+                    }
+                }
+            },
             Instr::Operation(op) => {
                 let op0:Data =  if let Some(data) = stack.pop() {
                     data
@@ -461,6 +583,7 @@ fn call_fn(prog: &Program, proc: &Proc, superstack: &[Data]) -> Result<Option<Da
             }
             _ => (),
         }
+        x += 1;
     }
 
     Ok(stack.pop())
@@ -480,7 +603,7 @@ pub fn execute(prog: &Program) -> Result<i64, ()> {
         return Err(());
     } else {
         crate::message(
-            crate::token::MessageType::Critical,
+            crate::token::MessageType::Error,
             "Program has no main() = int function",
         );
         return Err(());
diff --git a/src/vmrt/output.rs b/src/vmrt/output.rs
index d74631b..4f49ccf 100644
--- a/src/vmrt/output.rs
+++ b/src/vmrt/output.rs
@@ -2,7 +2,7 @@ use std::io::Write;
 
 fn print_to_file(file: &mut std::fs::File, prog: &crate::vmrt::Program) -> std::io::Result<()> {
     for proc in prog.procs.iter() {
-        writeln!(file, "\n0x{:#x}:", proc.0)?;
+        writeln!(file, "\n{:#x}:", proc.0)?;
 
         for instr in proc.1.code.iter() {
             writeln!(file, "{}", instr)?;
diff --git a/test.erpn b/test.erpn
index cc24e30..794496f 100644
--- a/test.erpn
+++ b/test.erpn
@@ -1,40 +1,10 @@
-pi:
-	Load Rat 5.1415926535
-foo:
-	Load Int 5
-	Load Int 6
-	Add Int
-	Store Int x
-	Load Arg x
-	Load Int 6
-	Lt Int
-	Unless
-		Load Bool true
-		Yield
-		Please
-		Load Arg x
-		Load Int 6
-		Lt Int
-		Unless
-			Load Bool true
-			Yield
-	Load Bool true
-	Yield
 main:
+	Load Int 2
 	Load Int 4
-	Store Int a
-	Call pi
-	Store Rat b
-	Load Bool true
-	Store Bool c
-	Load Int 3
-	Load Rat 4.0
-	Call foo
-	Store Bool r
-	Load Int 3
-	Load Rat 5.0
-	Call foo
-	Store Bool h
-	Load Int 4
-	Store Int b
-	Load Int 9
+	Eq Int
+	Unless
+		Load Int 1
+		Yield
+	Load Int 0
+	Yield
+