diff --git a/dev/src/idl/mod.rs b/dev/src/idl/mod.rs
index cc7f55e1..6533bcde 100644
--- a/dev/src/idl/mod.rs
+++ b/dev/src/idl/mod.rs
@@ -22,6 +22,8 @@ enum Token {
     // Tokens can be literal strings, of any length.
     #[token("type")]
     Type,
+    #[token("fn", priority = 5)]
+    Fn,
 
     #[token("enum")]
     Enum,
@@ -56,7 +58,7 @@ enum Token {
     #[token("->")]
     RArrow,
 
-    #[regex("[a-zA-Z_]+", |lex|{lex.slice().to_string()})]
+    #[regex("[a-zA-Z_][a-zA-Z_1234567890]+", |lex|{lex.slice().to_string()})]
     Identifier(String),
 
     #[regex("[1234567890]+", |lex|{lex.slice().parse::<u64>().unwrap()})]
@@ -86,9 +88,6 @@ pub fn build_idl(name: String) {
     println!("{:#?}", parse(tokens));
 }
 
-fn build(a: Vec<Token>) {
-}
-
 fn open_protocol(name: String) -> String {
     let path = format!("sysdata/idl/{}/src/protocol.aldi", name);
     let mut file = std::fs::File::open(path).unwrap();
diff --git a/dev/src/idl/parser.rs b/dev/src/idl/parser.rs
index f3cffa31..78ae4a6a 100644
--- a/dev/src/idl/parser.rs
+++ b/dev/src/idl/parser.rs
@@ -47,7 +47,7 @@ struct ProtocolDeclaration{
 #[derive(Debug, Clone, PartialEq)]
 struct FuncDeclaration {
     name : String,
-    input_types : Vec<String>,
+    arg_list : Vec<String>,
     return_type : String,
 }
 
@@ -87,6 +87,7 @@ fn declaration(tokens : &mut Peekable<Iter<'_, Token>>) -> Option<Declaration> {
             Token::Enum => Some(enum_decl(tokens)),
             Token::Struct => Some(struct_decl(tokens)),
             Token::Type => Some(type_declaration(tokens)),
+            Token::Protocol => Some(protocol_declaration(tokens)),
             _ => None,
         }
     }
@@ -214,3 +215,60 @@ fn parse_number(tokens : &mut Peekable<Iter<'_, Token>>) -> Option<u64> {
     result
 }
 
+fn protocol_declaration(tokens : &mut Peekable<Iter<'_, Token>>) -> Declaration {
+    consume(tokens, Token::Protocol);
+    let name = identifier(tokens).expect("Expected Identifier after `protocol`");
+    consume(tokens, Token::LBrace);
+    let mut interface = Vec::new();
+    match tokens.peek().expect("Unexpected EOF after LBrace") {
+        Token::RBrace => {},
+        _ => {
+            functions(tokens, &mut interface);
+        },
+    };
+    Declaration::ProtocolDeclaration(ProtocolDeclaration{name, interface})
+}
+
+fn functions(tokens : &mut Peekable<Iter<'_, Token>>, interface : &mut Vec<FuncDeclaration>) {
+    loop {
+        match function(tokens) {
+            Some(x) => interface.push(x),
+            None => break,
+        }
+    }
+}
+
+fn function(tokens : &mut Peekable<Iter<'_, Token>>) -> Option<FuncDeclaration>{
+    if let Some(Token::Fn) = tokens.peek() {
+        consume(tokens, Token::Fn);
+        let name = identifier(tokens).expect("Expected Identifier after `fn`");
+        consume(tokens, Token::LParen);
+        let arg_list = arg_list(tokens);
+        consume(tokens, Token::RParen);
+        consume(tokens, Token::RArrow);
+        let return_type = identifier(tokens).expect("Expected return type after `->");
+        Some(FuncDeclaration{name, arg_list, return_type})
+    } else {
+        None
+    }
+}
+
+fn arg_list(tokens : &mut Peekable<Iter<'_, Token>>) -> Vec<String> {
+    let mut result = Vec::new();
+    loop {
+        match identifier(tokens) {
+            None => break,
+            Some(i) =>{
+                result.push(i);
+                if **tokens.peek().expect("Unexpected EOF in argument list") == Token::Comma{
+                    consume(tokens, Token::Comma);
+                    match tokens.peek().expect("Unexpected EOF in argument list") {
+                        Token::Identifier(_) => {},
+                        _ => panic!("Unexpected symbol after Comma in argument list"),
+                    }
+                }
+            }
+        }
+    }
+    result
+}