extend the interpreter

src/token/mod.rs

@@ -12,6 +12,12 @@ pub const IDENT: &str = "IDENT";
 pub const INT: &str = "INT";
 pub const ASSIGN: &str = "=";
 pub const PLUS: &str = "+";
+pub const MINUS: &str = "-";
+pub const BANG: &str = "!";
+pub const ASTERISK: &str = "*";
+pub const SLASH: &str = "/";
+pub const LT: &str = "<";
+pub const GT: &str = ">";
 pub const COMMA: &str = ",";
 pub const SEMICOLON: &str = ";";
 pub const LPAREN: &str = "(";
@@ -20,11 +26,23 @@ pub const LBRACE: &str = "{";
 pub const RBRACE: &str = "}";
 pub const FUNCTION: &str = "FUNCTION";
 pub const LET: &str = "LET";
+pub const TRUE: &str = "TRUE";
+pub const FALSE: &str = "FALSE";
+pub const IF: &str = "IF";
+pub const ELSE: &str = "ELSE";
+pub const RETURN: &str = "RETURN";
+pub const EQ: &str = "EQ";
+pub const NQ: &str = "NQ";
 
 pub fn lookup_ident(ident: &str) -> &'static str {
     match ident {
         "fn" => FUNCTION,
         "let" => LET,
+        "true" => TRUE,
+        "false" => FALSE,
+        "if" => IF,
+        "else" => ELSE,
+        "return" => RETURN,
         _ => IDENT,
     }
 }