diff --git a/src/main.rs b/src/main.rs
index fb4473f..ddb7201 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -64,7 +64,9 @@ main() = int {
 
     if let Ok(mut tokens) = tokenize(source, &mut diagnostics) {
         if let Ok((fs, ds)) = parse(&mut tokens, &mut diagnostics, &settings) {
-            vmrt::compile(&fs, &ds);
+            if let Ok(prog) = vmrt::compile(&fs, &ds) {
+                vmrt::execute(&prog);
+            }
         }
     }
 
diff --git a/src/parser/data.rs b/src/parser/data.rs
index 556eace..2f123bb 100644
--- a/src/parser/data.rs
+++ b/src/parser/data.rs
@@ -146,6 +146,21 @@ impl<'a> Declr<'a> {
         }
     }
 
+    pub fn main() -> Self {
+        let mut main = Declr {
+            name: Some("main"),
+            args: None,
+            results: true,
+            result_typ: Some(Prim::Int),
+            info: None,
+            uuid: 0
+        };
+
+        main.gen_uuid();
+
+        main
+    }
+
     pub fn get_arg_ord(&self, name: &str) -> usize {
         if let Some(args) = self.args.as_ref() {
             for (x, arg) in args.iter().enumerate() {
diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index ad4c550..fcdef03 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -493,7 +493,7 @@ fn collapse_operation(
 ) -> Result<(), ()> {
 
     match operation {
-        Token::Operator(op, _, dbginf) => op.operate(operands, &dbginf, diagnostics)?,
+        Token::Operator(op, ref mut typehint, dbginf) => *typehint = Some(op.operate(operands, &dbginf, diagnostics)?),
         Token::Assign(name, ref mut typ, dbginf) => {
             check_var_typ(typ, operands, &dbginf, diagnostics)?;
             scope.decl_var((*name).to_owned(), typ.clone());
diff --git a/src/token/mod.rs b/src/token/mod.rs
index 29f0ac1..6bccd46 100644
--- a/src/token/mod.rs
+++ b/src/token/mod.rs
@@ -115,13 +115,23 @@ impl Operator {
         }
     }
 
+    fn operation_type(operands: &[Prim]) -> Option<Prim> {
+        let mut typ = None;
+        for op in operands.iter() {
+            op.merge_types(&mut typ);
+        }
+
+        typ
+    }
+
     fn present_types(
+        &self,
         operands: &[Prim],
         types: &[Prim],
         r#yield: Prim,
         info: &DebugInfo,
         diagnostics: &mut crate::parser::data::Diagnostics,
-    ) -> Result<Option<Prim>, ()> {
+    ) -> Result<(Option<Prim>, Option<Prim>), ()> {
 
         if operands.len() < types.len() {
             diagnostics.set_err(info, crate::msg::ERR74, format!(
@@ -134,27 +144,30 @@ impl Operator {
         }
 
         for (x, typ) in types.iter().enumerate() {
-            if typ != &operands[x] {
-                return Ok(None);
+            if !typ.is_equal(operands[x]) {
+                return Ok((None, None));
             }
         }
-        Ok(Some(r#yield))
+
+        // this combination fits
+        Ok((Some(r#yield), Self::operation_type(types) ))
     }
 
     fn check_types(
+        &self,
         operands: &[Prim],
         types: &[(&[Prim], Prim)],
         dbginf: &DebugInfo,
         diagnostics: &mut crate::parser::data::Diagnostics,
-    ) -> Result<Option<Prim>,()> {
+    ) -> Result<(Option<Prim>, Option<Prim>),()> {
         for combination in types.iter() {
-            if let Some(result) =
-                Self::present_types(operands, combination.0, combination.1, dbginf, diagnostics)?
+            if let (result, hint) =
+                self.present_types(operands, combination.0, combination.1, dbginf, diagnostics)?
             {
-                return Ok(Some(result));
+                return Ok((result, hint));
             }
         }
-        Ok(None)
+        Ok((None, None))
     }
 
     pub fn operate(
@@ -162,36 +175,36 @@ impl Operator {
         operands: &mut Vec<Prim>,
         info: &DebugInfo,
         diagnostics: &mut crate::parser::data::Diagnostics,
-    ) -> Result<(),()> {
+    ) -> Result<Prim,()> {
         // TODO: insert type hint
         match self {
             Operator::Add | Operator::Sub | Operator::Mul | Operator::Div => {
-                let types_valid =
-                    Self::check_types(operands, ARITHMETIC_TYPES, info, diagnostics)?;
+                let (types_valid, hint) =
+                    self.check_types(operands, ARITHMETIC_TYPES, info, diagnostics)?;
 
                 if let Some(result) = types_valid {
                     operands.pop();
                     operands.pop();
                     operands.push(result);
-                    return Ok(());
+                    return Ok(hint.unwrap());
                 } else {
                     diagnostics.set_err(info, crate::msg::ERR73, "expected two numbers");
                     return Err(());
                 }
             }
             Operator::And | Operator::Or | Operator::Xor => {
-                let types_valid = Self::check_types(
+                let types_valid = self.check_types(
                     operands,
                     &[(&[Prim::Bool, Prim::Bool], Prim::Bool)],
                     info,
                     diagnostics,
                 )?;
 
-                if let Some(result) = types_valid {
+                if let (Some(result), Some(hint)) = types_valid {
                     operands.pop();
                     operands.pop();
                     operands.push(result);
-                    return Ok(())
+                    return Ok(hint)
                 } else {
                     diagnostics.set_err(info, crate::msg::ERR73, "expected two booleans");
                     return Err(());
@@ -203,7 +216,7 @@ impl Operator {
             | Operator::Gt
             | Operator::GtEq
             | Operator::LtEq => {
-                let types_valid = Self::check_types(
+                let types_valid = self.check_types(
                     operands,
                     &[
                         (&[Prim::Int, Prim::Int], Prim::Bool),
@@ -225,11 +238,11 @@ impl Operator {
                     diagnostics,
                 )?;
 
-                if let Some(result) = types_valid {
+                if let (Some(result), Some(hint)) = types_valid {
                     operands.pop();
                     operands.pop();
                     operands.push(result);
-                    return Ok(());
+                    return Ok(hint);
                 } else {
                     diagnostics.set_err(info, crate::msg::ERR73, "expected either two booleans or two numbers");
                     return Err(());
@@ -315,6 +328,16 @@ impl Prim {
         };
     }
 
+    pub fn merge_types(&self, current: &mut Option<Prim>) {
+        if let Some(prim) = current {
+            if !prim.is_equal(*self) {
+                *current = None;
+            }
+        } else {
+            *current = Some(*self);
+        }
+    }
+
     pub fn is_equal(&self, value: Prim) -> bool {
         return match self {
             Prim::Bool => *self == value,
@@ -486,7 +509,7 @@ impl<'a> std::fmt::Display for Token<'a> {
             Token::Type(t, _) => f.write_fmt(format_args!("__Type {:?}", t)),
             Token::Word(w, _) => f.write_fmt(format_args!("__Word {:?}", w)),
             Token::Delemiter(d, _) => f.write_fmt(format_args!("__Delemiter {:?}", d)),
-            Token::Operator(o, _, _) => f.write_fmt(format_args!("{:?}", o)),
+            Token::Operator(o, hint, _) => f.write_fmt(format_args!("{:?} {:?}", o, hint.unwrap())),
             Token::Number(n, hint, _) => f.write_fmt(format_args!("Load {:?} {}", hint, n)),
             Token::LineBreak(_) => f.write_str("__Line-break"),
             Token::Func(name, _) => f.write_fmt(format_args!("Call {}", name)),
diff --git a/src/vmrt/mod.rs b/src/vmrt/mod.rs
index ff77ae5..b62062b 100644
--- a/src/vmrt/mod.rs
+++ b/src/vmrt/mod.rs
@@ -1,13 +1,13 @@
 use std::collections::{VecDeque, HashMap};
 
-use crate::{parser::data::*, token::{Token, NumHint}};
+use crate::{parser::data::*, token::{Token, NumHint, Prim}};
 
-#[derive(Debug)]
+#[derive(Debug, Clone, Copy)]
 enum Data {
     Int(i64),
     Rat(f64),
     Bool(bool),
-    Off(usize),
+    Off(u64),
 }
 
 #[derive(Debug)]
@@ -64,7 +64,7 @@ enum Instr {
     /// delete the last value from stack
     Pop,
     
-    /// push the value stored at offset onto the stack
+    /// 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,
@@ -91,10 +91,15 @@ enum Instr {
 /// +----------------------------------+
 /// | Parameter (n)                    |
 /// +----------------------------------+
+struct Proc {
+    code: Vec<Instr>,
+    args: usize,
+    addr: u64,
+}
 
 #[derive(Default)]
 pub struct Program {
-    code: HashMap<u64, Vec<Instr>>
+    code: HashMap<u64, Proc>
 }
 
 #[derive(Default)]
@@ -103,7 +108,7 @@ struct Compiletime<'a> {
     stacksize: usize,
 }
 
-fn parse_term<'a>(term: &VecDeque<Token<'a>>, x: usize, declr: &Vec<Declr<'a>>, ct: &mut Compiletime<'a>, code: &mut Vec<Instr>) {
+fn parse_term<'a>(term: &VecDeque<Token<'a>>, x: usize, declr: &Vec<Declr<'a>>, ct: &mut Compiletime<'a>, code: &mut Vec<Instr>) -> Result<(), ()>{
     for token in term.iter() {
         let instr = match token {
             Token::Number(value, hint, _) => {
@@ -130,13 +135,71 @@ fn parse_term<'a>(term: &VecDeque<Token<'a>>, x: usize, declr: &Vec<Declr<'a>>,
                 code.push(Instr::Load(*ct.vartable.get(name).unwrap()));
                 ct.stacksize += 1;
             }
-            Token::Operator(op, _, _) => {
+            Token::Operator(op, hint, _) => {
+                
                 code.push(match op {
                     crate::token::Operator::Or => Instr::Operation(Operation::Bool(BoolOp::Or)),
                     crate::token::Operator::And => Instr::Operation(Operation::Bool(BoolOp::And)),
                     crate::token::Operator::Xor => Instr::Operation(Operation::Bool(BoolOp::Xor)),
+
+                    crate::token::Operator::Add => match hint.unwrap() {
+                        Prim::Int => Instr::Operation(Operation::Int(IntOp::Add)),
+                        Prim::Rat => Instr::Operation(Operation::Rat(RatOp::Add)),
+                        _ => panic!()
+                    },
+                    crate::token::Operator::Sub => match hint.unwrap() {
+                        Prim::Int => Instr::Operation(Operation::Int(IntOp::Sub)),
+                        Prim::Rat => Instr::Operation(Operation::Rat(RatOp::Sub)),
+                        _ => panic!()
+                    },
+                    crate::token::Operator::Mul => match hint.unwrap() {
+                        Prim::Int => Instr::Operation(Operation::Int(IntOp::Mul)),
+                        Prim::Rat => Instr::Operation(Operation::Rat(RatOp::Mul)),
+                        _ => panic!()
+                    },
+                    crate::token::Operator::Div => match hint.unwrap() {
+                        Prim::Int => Instr::Operation(Operation::Int(IntOp::Div)),
+                        Prim::Rat => Instr::Operation(Operation::Rat(RatOp::Div)),
+                        _ => panic!()
+                    },
                     
-                    _ => panic!()
+                    crate::token::Operator::Eq => match hint.unwrap() {
+                        Prim::Int => Instr::Operation(Operation::Int(IntOp::CmpEq)),
+                        Prim::Rat => Instr::Operation(Operation::Rat(RatOp::CmpEq)),
+                        Prim::Bool => Instr::Operation(Operation::Bool(BoolOp::CmpEq)),
+                        _ => panic!()
+                    },
+                    crate::token::Operator::NotEq => match hint.unwrap() {
+                        Prim::Int => Instr::Operation(Operation::Int(IntOp::CmpNEq)),
+                        Prim::Rat => Instr::Operation(Operation::Rat(RatOp::CmpNEq)),
+                        Prim::Bool => Instr::Operation(Operation::Bool(BoolOp::CmpNEq)),
+                        _ => panic!()
+                    },
+                    crate::token::Operator::Lt => match hint.unwrap() {
+                        Prim::Int => Instr::Operation(Operation::Int(IntOp::CmpLt)),
+                        Prim::Rat => Instr::Operation(Operation::Rat(RatOp::CmpLt)),
+                        _ => panic!()
+                    },
+                    crate::token::Operator::Gt => match hint.unwrap() {
+                        Prim::Int => Instr::Operation(Operation::Int(IntOp::CmpGt)),
+                        Prim::Rat => Instr::Operation(Operation::Rat(RatOp::CmpGt)),
+                        _ => panic!()
+                    },
+                    crate::token::Operator::GtEq => match hint.unwrap() {
+                        Prim::Int => Instr::Operation(Operation::Int(IntOp::CmpGtEq)),
+                        Prim::Rat => Instr::Operation(Operation::Rat(RatOp::CmpGtEq)),
+                        _ => panic!()
+                    },
+                    crate::token::Operator::LtEq => match hint.unwrap() {
+                        Prim::Int => Instr::Operation(Operation::Int(IntOp::CmpLtEq)),
+                        Prim::Rat => Instr::Operation(Operation::Rat(RatOp::CmpLtEq)),
+                        _ => panic!()
+                    },
+
+                    crate::token::Operator::Assign => {
+                        crate::message(crate::token::MessageType::Critical, format!("Invalid operator: {:?}", op));
+                        return Err(());
+                    }
                 });
 
                 // TODO: operatiors
@@ -161,22 +224,26 @@ fn parse_term<'a>(term: &VecDeque<Token<'a>>, x: usize, declr: &Vec<Declr<'a>>,
             _ => ()
         };
     }
+    Ok(())
 }
 
-fn parse_block<'a>(block: &VecDeque<Expr<'a>>, x: usize, declr: &Vec<Declr<'a>>, ct: &mut Compiletime<'a>, prog: &mut Vec<Instr>) {
+fn parse_block<'a>(block: &VecDeque<Expr<'a>>, x: usize, declr: &Vec<Declr<'a>>, ct: &mut Compiletime<'a>, prog: &mut Vec<Instr>) -> Result<(), ()> {
     for expr in block.iter() {
-        compile_expr(expr, x, declr, ct, prog);
+        compile_expr(expr, x, declr, ct, prog)?;
     }
+    Ok(())
 }
 
-fn compile_expr<'a>(expr: &Expr<'a>, x: usize, declr: &Vec<Declr<'a>>, ct: &mut Compiletime<'a>, prog: &mut Vec<Instr>) {
+fn compile_expr<'a>(expr: &Expr<'a>, x: usize, declr: &Vec<Declr<'a>>, ct: &mut Compiletime<'a>, prog: &mut Vec<Instr>) -> Result<(), ()> {
     match expr {
-        Expr::Block(block) => parse_block(block, x, declr, ct, prog),
-        Expr::Term(term) => parse_term(term, x, declr, ct, prog),
+        Expr::Block(block) => parse_block(block, x, declr, ct, prog)?,
+        Expr::Term(term) => parse_term(term, x, declr, ct, prog)?,
     }
+
+    Ok(())
 }
 
-pub fn compile<'a>(funcs: &Vec<Func<'a>>, declrs: &Vec<Declr<'a>>) {
+pub fn compile<'a>(funcs: &Vec<Func<'a>>, declrs: &Vec<Declr<'a>>) -> Result<Program, ()> {
     let mut prog = Program::default();
 
     for (x, func) in funcs.iter().enumerate() {
@@ -186,10 +253,24 @@ pub fn compile<'a>(funcs: &Vec<Func<'a>>, declrs: &Vec<Declr<'a>>) {
         // at beginn the is the return address and the parameter on the stack
         ct.stacksize = declrs[x].args.as_ref().unwrap_or(&vec![]).len() + 1;
 
-        compile_expr(func.expr.as_ref().unwrap(), x, declrs, &mut ct, &mut code);
+        compile_expr(func.expr.as_ref().unwrap(), x, declrs, &mut ct, &mut code)?;
 
         println!("{:#?}", code);
 
         prog.code.insert(declrs[x].uuid(), code);
     }
+    Ok(prog)
+}
+
+pub fn execute(prog: &Program) -> Result<i64, ()> {
+    // declaration of entry function
+    let main_fn_declr = crate::parser::data::Declr::main();
+
+    if let Some(main_fn) = prog.code.get(&main_fn_declr.uuid()) {
+         
+        Ok(0)
+    } else {
+        crate::message(crate::token::MessageType::Critical, "Program has no main() = int function");
+        return Err(());
+    }
 }
diff --git a/test.erpn b/test.erpn
index 0434502..cc24e30 100644
--- a/test.erpn
+++ b/test.erpn
@@ -3,18 +3,18 @@ pi:
 foo:
 	Load Int 5
 	Load Int 6
-	Add
+	Add Int
 	Store Int x
 	Load Arg x
 	Load Int 6
-	Lt
+	Lt Int
 	Unless
 		Load Bool true
 		Yield
 		Please
 		Load Arg x
 		Load Int 6
-		Lt
+		Lt Int
 		Unless
 			Load Bool true
 			Yield