diff --git a/selib/math.yard b/selib/math.yard
new file mode 100644
index 0000000..dc0c825
--- /dev/null
+++ b/selib/math.yard
@@ -0,0 +1,24 @@
+@pragma(once)
+
+@feature(conv, math)
+@author(Sven Vogel)
+
+floor(x:rat) = rat {
+    to_rat(to_int(x))
+}
+
+round(x:rat) = rat {
+    to_rat(to_int(x + 0.5))
+}
+
+ceil(x:rat) = rat {
+    to_rat(to_int(x + 1.0))
+}
+
+fract(x:rat) = rat {
+    x - floor(x)
+}
+
+log(x:rat, b:rat) = rat {
+    log(x) / log(b)
+}
\ No newline at end of file
diff --git a/src/builtin/mod.rs b/src/builtin/mod.rs
new file mode 100644
index 0000000..65128cd
--- /dev/null
+++ b/src/builtin/mod.rs
@@ -0,0 +1,52 @@
+/// module for builtin functons
+/// and the SENI-module
+use crate::{parser::data::{Declr, Func}, vmrt::Data};
+
+use self::modules::Module;
+
+pub mod modules;
+
+type Function = &'static dyn Fn(&[Data]) -> Result<Option<Data>, ()>;
+
+#[derive(Clone)]
+pub struct BuiltinFun {
+    declr: Declr<'static>,
+    func: Function
+}
+
+impl BuiltinFun {
+    
+    pub fn declr(&self) -> Declr<'static> {
+        self.declr.clone()
+    }
+
+    pub fn func(&self) -> crate::parser::data::Func<'static> {
+        Func {
+            expr: None,
+            is_builtin: true,
+            raw: None
+        }
+    }
+
+    pub fn get_function(&self) -> Function {
+        self.func
+    }
+}
+
+pub fn get_builtin_funs(mods: &[Module]) -> Vec<BuiltinFun> {
+    let mut funs = vec![
+        BuiltinFun {
+            declr: Declr::generate_builtin("say_hello", vec![], None),
+            func: &say_hello
+        },
+    ];
+
+    funs.append(&mut modules::get_submodules(mods));
+
+    return funs;
+}
+
+fn say_hello(_args: &[Data]) -> Result<Option<Data>, ()> {
+    println!("hello!");
+    Ok(None)
+}
\ No newline at end of file
diff --git a/src/builtin/modules/conv.rs b/src/builtin/modules/conv.rs
new file mode 100644
index 0000000..d511431
--- /dev/null
+++ b/src/builtin/modules/conv.rs
@@ -0,0 +1,50 @@
+use crate::{token::Prim, parser::data::{Declr}, vmrt::Data, builtin::BuiltinFun};
+
+pub fn int_to_rat(args: &[Data]) -> Result<Option<Data>, ()> {
+    match args [0] {
+        Data::Int(val) => Ok(Some(Data::Rat(val as f64))),
+        _ => Err(())
+    }
+}
+
+pub fn rat_to_int(args: &[Data]) -> Result<Option<Data>, ()> {
+    match args[0] {
+        Data::Rat(val) => Ok(Some(Data::Int(val as i64))),
+        _ => Err(())
+    }
+}
+
+pub fn str_to_int(args: &[Data]) -> Result<Option<Data>, ()> {
+    match &args[0] {
+        Data::Str(val) => Ok(Some(Data::Int(val.parse().unwrap_or(0)))),
+        _ => Err(())
+    }
+}
+
+pub fn str_to_rat(args: &[Data]) -> Result<Option<Data>, ()> {
+    match &args[0] {
+        Data::Str(val) => Ok(Some(Data::Rat(val.parse().unwrap_or(0.0)))),
+        _ => Err(())
+    }
+}
+
+pub fn get_module_funs<'a>() -> Vec<crate::builtin::BuiltinFun> {
+    vec![
+        BuiltinFun {
+            declr: Declr::generate_builtin("to_rat", vec![("x", Prim::Int)], Some(Prim::Rat)),
+            func: &int_to_rat
+        },
+        BuiltinFun {
+            declr: Declr::generate_builtin("to_int", vec![("x", Prim::Rat)], Some(Prim::Int)),
+            func: &rat_to_int
+        },
+        BuiltinFun {
+            declr: Declr::generate_builtin("parse_int", vec![("text", Prim::Str)], Some(Prim::Int)),
+            func: &str_to_int
+        },
+        BuiltinFun {
+            declr: Declr::generate_builtin("parse_rat", vec![("text", Prim::Str)], Some(Prim::Rat)),
+            func: &str_to_rat
+        }
+    ]
+}
\ No newline at end of file
diff --git a/src/builtin/modules/io.rs b/src/builtin/modules/io.rs
new file mode 100644
index 0000000..58922bf
--- /dev/null
+++ b/src/builtin/modules/io.rs
@@ -0,0 +1,26 @@
+use crate::{token::Prim, parser::data::{Declr}, vmrt::Data, builtin::BuiltinFun};
+
+pub fn print(args: &[Data]) -> Result<Option<Data>, ()> {
+    let text = args[0].to_str()?;
+    print!("{}", text);
+    Ok(None)
+}
+
+pub fn println(args: &[Data]) -> Result<Option<Data>, ()> {
+    let text = args[0].to_str()?;
+    println!("{}", text);
+    Ok(None)
+}
+
+pub fn get_module_funs<'a>() -> Vec<crate::builtin::BuiltinFun> {
+    vec![
+        BuiltinFun {
+            declr: Declr::generate_builtin("print", vec![("text", Prim::Str)], None),
+            func: &print
+        },
+        BuiltinFun {
+            declr: Declr::generate_builtin("println", vec![("text", Prim::Str)], None),
+            func: &println
+        },
+    ]
+}
\ No newline at end of file
diff --git a/src/builtin/modules/math.rs b/src/builtin/modules/math.rs
new file mode 100644
index 0000000..dc2cbae
--- /dev/null
+++ b/src/builtin/modules/math.rs
@@ -0,0 +1,57 @@
+use crate::{token::Prim, parser::data::{Declr}, vmrt::Data, builtin::BuiltinFun};
+
+pub fn cos(args: &[Data]) -> Result<Option<Data>, ()> {
+    Ok(Some(Data::Rat(args[0].to_float()?.cos())))
+}
+
+pub fn sin(args: &[Data]) -> Result<Option<Data>, ()> {
+    Ok(Some(Data::Rat(args[0].to_float()?.sin())))
+}
+
+pub fn tan(args: &[Data]) -> Result<Option<Data>, ()> {
+    Ok(Some(Data::Rat(args[0].to_float()?.tan())))
+}
+
+pub fn ln(args: &[Data]) -> Result<Option<Data>, ()> {
+    Ok(Some(Data::Rat(args[0].to_float()?.ln())))
+}
+
+pub fn sqrt(args: &[Data]) -> Result<Option<Data>, ()> {
+    Ok(Some(Data::Rat(args[0].to_float()?.sqrt())))
+}
+
+pub fn pow(args: &[Data]) -> Result<Option<Data>, ()> {
+    let x = args[0].to_float()?;
+    let y = args[1].to_float()?;
+
+    Ok(Some(Data::Rat(y.powf(x))))
+}
+
+pub fn get_module_funs<'a>() -> Vec<crate::builtin::BuiltinFun> {
+    vec![
+        BuiltinFun {
+            declr: Declr::generate_builtin("cos", vec![("x", Prim::Int)], Some(Prim::Rat)),
+            func: &cos
+        },
+        BuiltinFun {
+            declr: Declr::generate_builtin("pow", vec![("x", Prim::Rat), ("y", Prim::Rat)], Some(Prim::Rat)),
+            func: &pow
+        },
+        BuiltinFun {
+            declr: Declr::generate_builtin("sin", vec![("x", Prim::Int)], Some(Prim::Rat)),
+            func: &sin
+        },
+        BuiltinFun {
+            declr: Declr::generate_builtin("tan", vec![("x", Prim::Int)], Some(Prim::Rat)),
+            func: &tan
+        },
+        BuiltinFun {
+            declr: Declr::generate_builtin("ln", vec![("x", Prim::Int)], Some(Prim::Rat)),
+            func: &ln
+        },
+        BuiltinFun {
+            declr: Declr::generate_builtin("sqrt", vec![("x", Prim::Int)], Some(Prim::Rat)),
+            func: &sqrt
+        },
+    ]
+}
\ No newline at end of file
diff --git a/src/builtin/modules/mod.rs b/src/builtin/modules/mod.rs
new file mode 100644
index 0000000..4611da3
--- /dev/null
+++ b/src/builtin/modules/mod.rs
@@ -0,0 +1,47 @@
+
+pub mod conv;
+pub mod math;
+pub mod io;
+pub mod os;
+
+#[derive(PartialEq, Eq)]
+pub enum Module {
+    Conv,
+    Math,
+    IO,
+    OS,
+}
+
+impl Module {
+    
+    pub fn from_list(text: &str) -> Vec<Module> {
+        let mut vec = vec![];
+
+        for word in text.split(',') {
+            match word.trim() {
+                "conv" => vec.push(Module::Conv),
+                "math" => vec.push(Module::Math),
+                "io" => vec.push(Module::IO),
+                "os" => vec.push(Module::OS),
+                _ => crate::message(crate::token::MessageType::Warning, format!("unknown module: `{}`", word))
+            }
+        }
+
+        vec
+    }
+}
+
+pub fn get_submodules<'a>(modules: &[Module]) -> Vec<super::BuiltinFun> {
+    let mut funs = vec![];
+
+    for module in modules {
+        match module {
+            Module::Conv => funs.append(&mut conv::get_module_funs()),
+            Module::Math => funs.append(&mut math::get_module_funs()),
+            Module::IO => funs.append(&mut io::get_module_funs()),
+            Module::OS => funs.append(&mut os::get_module_funs()),
+        }
+    }
+
+    funs
+}
\ No newline at end of file
diff --git a/src/builtin/modules/os.rs b/src/builtin/modules/os.rs
new file mode 100644
index 0000000..0086fe9
--- /dev/null
+++ b/src/builtin/modules/os.rs
@@ -0,0 +1,21 @@
+use crate::{token::Prim, parser::data::{Declr}, vmrt::Data, builtin::BuiltinFun};
+
+pub fn get_os(_: &[Data]) -> Result<Option<Data>, ()> {
+    
+    if cfg!(windows) {
+        return Ok(Some(Data::Str(String::from("Windows"))))
+    } else if cfg!(unix) {
+        return Ok(Some(Data::Str(String::from("UNIX"))))
+    }
+
+    Ok(None)
+}
+
+pub fn get_module_funs<'a>() -> Vec<crate::builtin::BuiltinFun> {
+    vec![
+        BuiltinFun {
+            declr: Declr::generate_builtin("get_os", vec![], Some(Prim::Str)),
+            func: &get_os
+        },
+    ]
+}
\ No newline at end of file
diff --git a/src/direct/mod.rs b/src/direct/mod.rs
new file mode 100644
index 0000000..eb7e371
--- /dev/null
+++ b/src/direct/mod.rs
@@ -0,0 +1,106 @@
+use std::{collections::VecDeque};
+
+use crate::{token::{Token}, builtin::modules::Module};
+
+#[derive(Default)]
+pub struct LangSpecs {
+    /// builtin modules for extra builtin functions
+    builtin_features: Vec<crate::builtin::modules::Module>,
+    lang_version: u32,
+    authors: Vec<String>,
+    embedded_files: Vec<String>,
+}
+
+impl LangSpecs {
+    
+    pub fn features(&self) -> &[crate::builtin::modules::Module] {
+        &self.builtin_features
+    }
+}
+
+pub fn resolve_directives(tokens: &mut VecDeque<Token>) -> LangSpecs {
+    let mut specs = LangSpecs::default();
+
+    for token in tokens.iter() {
+        match token {
+            Token::CompilerDirective(text, _) => parse_directive(text, &mut specs),
+            _ => ()
+        }
+    }
+
+    // remove compiler directives from source
+    tokens.retain(|token| match token {
+        Token::CompilerDirective(_, _) => false,
+        _ => true
+    });
+
+    specs
+}
+
+static DIRECTIVE_REGEX_SRC: &'static str = concat!(
+    r"@feature\(((?:\s*[\w]+\s*,?)*)\)",
+    r"|@version\(\s*([0-9]{3})\s*\)",
+    r"|@author\((.*)\)",
+    r"|@embed\((.*)\)"
+);
+
+lazy_static::lazy_static! {
+    static ref DIRECTIVE_REGEX: regex::Regex = regex::Regex::new(DIRECTIVE_REGEX_SRC).unwrap();
+}
+
+pub fn from_list(text: &str) -> Vec<String> {
+    let mut vec = vec![];
+
+    for word in text.split(',') {
+        vec.push(String::from(word.trim()))
+    }
+
+    vec
+}
+
+fn parse_directive(text: &str, specs: &mut LangSpecs) {
+    
+    for cap in DIRECTIVE_REGEX.captures_iter(text) {
+        let mut enumerator = cap.iter().enumerate();
+        loop {
+            let next = enumerator.next();
+            if next.is_none() {
+                break;
+            }
+
+            let (i, group) = next.unwrap();
+
+            // ignore first group as its the entire match,
+            // as well as the 1st group (= comments)
+            if i < 1 {
+                continue;
+            }
+
+            if let Some(mat) = group {
+                match i {
+                    1 => {
+                        specs.builtin_features.append(&mut Module::from_list(mat.as_str()));
+                        return;
+                    },
+                    2 => {
+                        specs.lang_version = mat.as_str().parse().unwrap();
+                        return;
+                    },
+                    3 => {
+                        specs.authors.push(String::from(mat.as_str()));
+                        return;
+                    },
+                    4 => {
+                        specs.embedded_files.append(&mut from_list(mat.as_str()));
+                        crate::message(crate::token::MessageType::Warning, "Embed directive not working at current state");
+                        return;
+                    },
+                    _ => crate::message(crate::token::MessageType::Warning, format!("unknown directive: `{}`", text)),
+                }
+                break;
+            }
+        }
+    }
+    
+    crate::message(crate::token::MessageType::Warning, format!("unknown directive: `{}`", text));
+}
\ No newline at end of file
diff --git a/src/seni/mod.rs b/src/seni/mod.rs
new file mode 100644
index 0000000..81a75f1
--- /dev/null
+++ b/src/seni/mod.rs
@@ -0,0 +1,2 @@
+/// SENI - Standard Edition Native Interface (for rust)
+
diff --git a/src/srcio/mod.rs b/src/srcio/mod.rs
new file mode 100644
index 0000000..d06d91b
--- /dev/null
+++ b/src/srcio/mod.rs
@@ -0,0 +1,31 @@
+use std::{fs};
+
+pub struct CodeSrc {
+    _path: String,
+    src: String,
+}
+
+impl CodeSrc {
+    
+    pub fn new(path: &String) -> Result<CodeSrc, String> {
+        Ok(Self {
+            _path: path.to_owned(),
+            src: Self::read_code(path)?,
+        })
+    }
+
+    fn read_code(path: &String) -> Result<String, String> {
+        let result = fs::read_to_string(path);
+        
+        // read the source
+        if let Ok(src) = result {
+            return Ok(src);
+        }
+
+        Err(format!("unable to fetch source code from {}: {}", path, result.err().unwrap()))
+    }
+
+    pub fn code(&self) -> &String {
+        &self.src
+    }
+}
\ No newline at end of file
diff --git a/test.yard b/test.yard
new file mode 100644
index 0000000..82f9984
--- /dev/null
+++ b/test.yard
@@ -0,0 +1,35 @@
+@feature(io)
+@version(100)
+@author(Sven Vogel)
+
+// recursion!
+fac(x:int) = int {
+    despite x != 1 {
+        yield 1;
+    }
+
+    yield fac(x - 1) * x
+}
+
+main() = int {
+    
+    x = 0
+    loop {
+
+        until x > 9 {
+            despite x != 5 {
+                x = x + 1
+                cont
+            }
+
+            println(""..x);
+            x = x + 1
+        }
+
+        break
+    }
+
+    println(""..fract(456.3928));
+
+    yield 0
+}
\ No newline at end of file