implemented very simple repl

src/main.cpp

@@ -1,9 +1,8 @@
-#include "token/type.hpp"
+#include "repl/repl.hpp"
 
 #include <iostream>
 
 int main() {
-    token::type eof = token::type::ILLEGAL;
-    std::cout << eof << std::endl;
+    repl::start(std::cin, std::cout);
     return 0;
 }

src/repl/repl.cpp

@@ -0,0 +1,30 @@
+#include "repl.hpp"
+
+#include "lexer/lexer.hpp"
+
+#include <sstream>
+#include <string>
+
+static const std::string PROMPT = ">> ";
+
+namespace repl {
+
+    void start(std::istream& in, std::ostream& out) {
+        while (true) {
+            out << PROMPT;
+            std::string line;
+            if (!std::getline(in, line))
+                return;
+
+            std::istringstream ss(line);
+
+            lexer::lexer l{ss};
+            for (token::token tok = l.next_token();
+                 tok.type != token::type::END_OF_FILE;
+                 tok = l.next_token())
+                out << tok << " ";
+            out << std::endl;
+        }
+    }
+
+} // namespace repl

src/repl/repl.hpp

@@ -0,0 +1,6 @@
+#include <istream>
+#include <ostream>
+
+namespace repl {
+    void start(std::istream&, std::ostream&);
+}

src/token/token.hpp

@@ -13,4 +13,8 @@ namespace token {
 
         token(::token::type t, char c): type(t), literal(1, c) {}
     };
+
+    inline std::ostream& operator<<(std::ostream& os, token tok) {
+        return os << tok.type << '(' << tok.literal << ')';
+    }
 } // namespace token