diff --git a/sm-test-files/actual-testing/math.sm b/sm-test-files/actual-testing/math.sm
new file mode 100644
index 0000000..af225e0
--- /dev/null
+++ b/sm-test-files/actual-testing/math.sm
@@ -0,0 +1,4 @@
+2+5
+3 + 6
+6 / 4
+2.5 + 1.7
diff --git a/src/main.rs b/src/main.rs
index fe0c251..8731b4e 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,16 +1,26 @@
 use std::env;
 use std::fs;
 
-mod preprocessor;
+mod shell;
+mod parsing;
+
+use parsing::preprocessor::preprocess;
 
 fn main() {
     let args: Vec<String> = env::args().collect();
-    let file = fs::read_to_string(&args[1]).expect("Couldnt read file:");
 
-    println!("{:?}", preprocessor::preprocess(file));
+    let run_shell = String::from("RUN_SH");
+    let path: &String = match args.get(1) {
+        Some(path) => path,
+        None => &run_shell,
+    };
+
+    if path == "RUN_SH" {
+        shell::run_shell();
+    } else {
+        let file = fs::read_to_string(path).expect("Couldnt read file:");
+
+        let code = preprocess(file);
+    }
 }
 
-//fn parse_and_interpret(code: String) {
-
-//}
-
diff --git a/src/parsing/lexer.rs b/src/parsing/lexer.rs
new file mode 100644
index 0000000..260b4ba
--- /dev/null
+++ b/src/parsing/lexer.rs
@@ -0,0 +1,62 @@
+use preprocessor::preprocess;
+
+struct Lexer {
+    code: String,
+    pos: usize,
+    current: Option<char>,
+}
+
+impl Lexer {
+    pub fn new(code: String) -> Lexer {
+        Lexer {
+            code,
+            pos: 1,
+            current: None,
+        }
+    }
+
+    pub fn next(&mut self) {
+        self.pos += 1;
+        self.current = if self.pos < self.code.len() {
+            self.code.chars().nth(self.pos)
+        } else {
+            None
+        };
+    }
+
+    pub fn tokenize(&mut self) {
+        let mut tokens: Vec<Token> = vec![];
+        self.code = preprocess(self.code);
+        
+        loop {
+            //let token = match self.current {
+                //Some('+') => Token::ADD,
+                //Some('-') => Token::SUBTRACT,
+                //Some('*') => Token::MULTIPLY,
+                //Some('/') => Token::DIVIDE,
+                //Some('(') => Token::LBRACK,
+                //Some(')') => Token::RBRACK,
+                //Some(' ') => continue,
+                //Some('\n') => continue,
+                //None => break,
+                //Some(_) => continue,
+            //};
+
+            tokens.push(match self.current {
+                Some('+') => Token::ADD,
+                Some('-') => Token::SUBTRACT,
+                Some('*') => Token::MULTIPLY,
+                Some('/') => Token::DIVIDE,
+                Some('(') => Token::LBRACK,
+                Some(')') => Token::RBRACK,
+                Some(' ') => continue,
+                Some('\n') => continue,
+                None => break,
+                Some(_) => continue,
+            });
+            self.next();
+        }
+
+        println!("{:?}", tokens);
+    }
+}
diff --git a/src/parsing/mod.rs b/src/parsing/mod.rs
new file mode 100644
index 0000000..20299d9
--- /dev/null
+++ b/src/parsing/mod.rs
@@ -0,0 +1,3 @@
+pub mod lexer;
+pub mod preprocessor;
+pub mod token;
diff --git a/src/preprocessor.rs b/src/parsing/preprocessor.rs
similarity index 100%
rename from src/preprocessor.rs
rename to src/parsing/preprocessor.rs
diff --git a/src/parsing/token.rs b/src/parsing/token.rs
new file mode 100644
index 0000000..cd6f344
--- /dev/null
+++ b/src/parsing/token.rs
@@ -0,0 +1,13 @@
+pub enum Token {
+    INT,
+    FLOAT,
+    ADD,
+    SUBTRACT,
+    MULTIPLY,
+    DIVIDE,
+    LBRACK,
+    RBRACK,
+}
+
+impl Token {}
+
diff --git a/src/shell.rs b/src/shell.rs
new file mode 100644
index 0000000..f918835
--- /dev/null
+++ b/src/shell.rs
@@ -0,0 +1,18 @@
+use std::io;
+
+pub fn run_shell() {
+    'shell: loop {
+        let string = get_line();
+        if string.eq("q\n") || string.eq("quit\n") {
+            break 'shell;
+        }
+        println!("{}", string);
+    }
+}
+
+fn get_line() -> String {
+    let mut line = String::new();
+    io::stdin().read_line(&mut line).unwrap();
+    line
+}
+
diff --git a/src/stdlib/io.rs b/src/stdlib/io.rs
new file mode 100644
index 0000000..e69de29