Add binop impl lexing

examples/custom_binop.reid

@@ -0,0 +1,12 @@
+// Arithmetic, function calls and imports!
+
+impl binop (lhs: u32) + (rhs: u32) -> u32 {
+
+}
+
+fn main() -> u32 {
+  let value = 6;
+  let other = 15;
+
+  return value * other + 7 * -value;
+}

reid/src/ast/mod.rs

@@ -207,6 +207,15 @@ pub enum TopLevelStatement {
     ExternFunction(FunctionSignature),
     FunctionDefinition(FunctionDefinition),
     TypeDefinition(TypeDefinition),
+    BinopDefinition(BinopDefinition),
+}
+
+#[derive(Debug)]
+pub struct BinopDefinition {
+    lhs: (String, Type),
+    rhs: (String, Type),
+    return_ty: Type,
+    block: Block,
 }
 
 #[derive(Debug)]

reid/src/ast/process.rs

@@ -97,6 +97,7 @@ impl ast::Module {
                     };
                     typedefs.push(def);
                 }
+                BinopDefinition(binop_definition) => todo!(),
             }
         }
 

reid/src/lexer.rs

@@ -46,8 +46,12 @@ pub enum Token {
     While,
     /// `for`
     For,
-    /// `In`
+    /// `in`
     In,
+    /// `impl`
+    Impl,
+    /// `binop`
+    Binop,
 
     // Symbols
     /// `;`
@@ -145,6 +149,8 @@ impl ToString for Token {
             Token::For => String::from("for"),
             Token::In => String::from("in"),
             Token::While => String::from("while"),
+            Token::Impl => String::from("impl"),
+            Token::Binop => String::from("binop"),
             Token::Semi => String::from(';'),
             Token::Equals => String::from('='),
             Token::Colon => String::from(':'),
@@ -334,6 +340,8 @@ pub fn tokenize<T: Into<String>>(to_tokenize: T) -> Result<Vec<FullToken>, Error
                     "for" => Token::For,
                     "while" => Token::While,
                     "in" => Token::In,
+                    "impl" => Token::Impl,
+                    "binop" => Token::Binop,
                     _ => Token::Identifier(value),
                 };
                 variant