diff --git a/examples/factorial b/examples/factorial
new file mode 100644
index 0000000..d4609d1
--- /dev/null
+++ b/examples/factorial
@@ -0,0 +1,20 @@
+ENTRY 22
+LOAD -3
+CONST 2
+LT
+BRF 10
+CONST 1
+RET
+LOAD -3
+LOAD -3
+CONST 1
+SUB
+CALL 0 1
+MULT
+RET
+CONST 12
+CALL 0 1
+IPRINT
+CONST 10
+PRINT
+HALT
diff --git a/src/main.rs b/src/main.rs
index c817533..06d9dee 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,14 +2,45 @@ use std::fs::File;
 use std::io;
 use std::io::Read;
 use std::env;
+use std::collections::HashMap;
 
-const EXEC: [(i32, (&'static str, i32)); 1] = [
-    (0, ("add", 0))
+const EXEC_RPR: [(&'static str, i32); 28] = [
+    ("entry", 1),
+    ("add", 0),
+    ("sub", 0),
+    ("mult", 0),
+    ("div", 0),
+    ("mod", 0),
+    ("lt", 0),
+    ("eq", 0),
+    ("gt", 0),
+    ("br", 1),
+    ("brt", 1),
+    ("brf", 1),
+    ("const", 1),
+    ("load", 1),
+    ("gload", 1),
+    ("store", 1),
+    ("gstore", 1),
+    ("print", 0),
+    ("pop", 0),
+    ("halt", 0),
+    ("leq", 0),
+    ("geq", 0),
+    ("call", 2),
+    ("ret", 0),
+    ("iprint", 0),
+    ("fetch", 0),
+    ("inc", 0),
+    ("dec", 0)
 ];
 
-struct Exec {
-    arguments: i32,
-    name: String
+fn build_opcodes() -> HashMap<&'static str, (i64, i32)> {
+    let mut opcodes = HashMap::new();
+    for (i, elem) in EXEC_RPR.iter().enumerate() {
+        opcodes.insert((*elem).0, (i as i64, (*elem).1));
+    }
+    return opcodes;
 }
 
 fn usage(pname: String) {
@@ -23,14 +54,41 @@ fn get_contents(fname: String) -> Result<String, io::Error> {
     Ok(contents)
 }
 
-fn parse(contents: String) -> Vec<Exec> {
-    return vec![];
+fn parse(contents: String, opcodes: HashMap<&'static str, (i64, i32)>) -> Vec<i64> {
+    let mut code = Vec::new();
+    for line in contents.split("\n") {
+        if line.is_empty() { continue }
+        let tmp = line.split(" ").map(String::from).collect::<Vec<String>>();
+        let (op, args) = tmp.split_first().expect("malformatted line!");
+        let opcode: &str = &op.to_lowercase()[..];
+        match opcodes.get(opcode) {
+            Some(v) => {
+                code.push(v.0);
+                if args.len() as i32 != v.1 {
+                    panic!("Expected {} arguments for opcode {}, but got {}!", v.1, opcode, args.len());
+                }
+                for elem in args {
+                    match elem.parse::<i64>() {
+                        Ok(v) => code.push(v),
+                        _ => panic!("Could not parse argument {} to instruction {} as number!", elem, opcode)
+                    }
+                }
+            }
+            None => panic!("Do not know opcode {}!", opcode)
+        }
+    }
+    return code
 }
 
-fn exec(instructions: Vec<Exec>) {
+fn exec(instructions: Vec<i64>) {
+    for elem in instructions {
+        println!("{}", elem);
+    }
 }
 
 fn main() {
+    let opcodes = build_opcodes();
+
     let args: Vec<_> = env::args().collect();
 
     if args.len() != 2 {
@@ -49,7 +107,7 @@ fn main() {
         }
     };
 
-    let parsed = parse(contents);
+    let parsed = parse(contents, opcodes);
 
     let execd = exec(parsed);
 }