diff --git a/examples/string.fk b/examples/string.fk
new file mode 100644
index 0000000..5c2f550
--- /dev/null
+++ b/examples/string.fk
@@ -0,0 +1,3 @@
+(assert= 'hello world' (cat 'hello' ' world'))
+(assert= 'yoyoyo' (dup 'yo' 3))
+(assert= 'e' (char-at 'hello' 1))
\ No newline at end of file
diff --git a/libstd/fun.cpp b/libstd/fun.cpp
index 2ba76b5..1565b00 100644
--- a/libstd/fun.cpp
+++ b/libstd/fun.cpp
@@ -18,24 +18,6 @@
   return std::make_shared<Constant>(TYPE_BOOL, res, loc)
 
 
-#define FLOAT_OP(NEUTRAL, OP)                                           \
-  if (args.empty())                                                     \
-    {                                                                   \
-      return std::make_shared<Constant>(TYPE_FLOAT, NEUTRAL, loc);      \
-    }                                                                   \
-                                                                        \
-  float result = std::get<float>(args[0]->value());                     \
-                                                                        \
-  for (size_t i=1; i<args.size(); i++)                                  \
-    {                                                                   \
-      result = result OP std::get<float>(args[i]->value());             \
-    }                                                                   \
-  if (args.size() == 1)                                                 \
-    {                                                                   \
-      return std::make_shared<Constant>(TYPE_FLOAT, OP result, loc);    \
-    }                                                                   \
-  return std::make_shared<Constant>(TYPE_FLOAT, result, loc)
-
 namespace fkstd
 {
   STDRET assert_eq(Loc loc, Module&, STDARGS args)
@@ -184,7 +166,7 @@ namespace fkstd
     return std::make_shared<Constant>(TYPE_INT, result, loc);
   }
 
-  STDRET add_float(Loc loc, Module& mod, STDARGS args)
+  STDRET add_float(Loc loc, Module&, STDARGS args)
   {
     if (args.empty())
       {
@@ -201,7 +183,7 @@ namespace fkstd
     return std::make_shared<Constant>(TYPE_FLOAT, result, loc);
   }
 
-  STDRET sub_float(Loc loc, Module& mod, STDARGS args)
+  STDRET sub_float(Loc loc, Module&, STDARGS args)
   {
     if (args.empty())
       {
@@ -223,7 +205,7 @@ namespace fkstd
     return std::make_shared<Constant>(TYPE_FLOAT, result, loc);
   }
 
-  STDRET mul_float(Loc loc, Module& mod, STDARGS args)
+  STDRET mul_float(Loc loc, Module&, STDARGS args)
   {
     if (args.empty())
       {
@@ -240,7 +222,7 @@ namespace fkstd
     return std::make_shared<Constant>(TYPE_FLOAT, result, loc);
   }
 
-  STDRET div_float(Loc loc, Module& mod, STDARGS args)
+  STDRET div_float(Loc loc, Module&, STDARGS args)
   {
     if (args.empty())
       {
@@ -262,7 +244,7 @@ namespace fkstd
     return std::make_shared<Constant>(TYPE_FLOAT, result, loc);
   }
 
-  STDRET mod_float(Loc loc, Module& mod, STDARGS args)
+  STDRET mod_float(Loc loc, Module&, STDARGS args)
   {
     if (args.empty())
       {
@@ -279,7 +261,7 @@ namespace fkstd
     return std::make_shared<Constant>(TYPE_FLOAT, result, loc);
   }
 
-  STDRET pow_float(Loc loc, Module& mod, STDARGS args)
+  STDRET pow_float(Loc loc, Module&, STDARGS args)
   {
     if (args.empty())
       {
@@ -356,4 +338,45 @@ namespace fkstd
 
     return val->at(std::get<int>(args.back()->value()));
   }
+
+  STDRET string_cat(Loc loc, Module&, STDARGS args)
+  {
+    if (args.empty())
+      {
+        return std::make_shared<Constant>(TYPE_STRING, "", loc);
+      }
+
+    std::string value = std::get<std::string>(args[0]->value());
+
+    for (size_t i=1; i<args.size(); i++)
+      {
+        value += std::get<std::string>(args[i]->value());
+      }
+
+    return std::make_shared<Constant>(TYPE_STRING, value, loc);
+  }
+
+  STDRET string_dup(Loc loc, Module&, STDARGS args)
+  {
+    std::string str = std::get<std::string>(args[0]->value());
+    int n = std::get<int>(args[1]->value());
+    std::string res;
+
+    for (int i=0; i<n; i++)
+      {
+        res += str;
+      }
+
+    return std::make_shared<Constant>(TYPE_STRING, res, loc);
+  }
+
+  STDRET char_at(Loc loc, Module&, STDARGS args)
+  {
+    std::string str = std::get<std::string>(args[0]->value());
+    int n = std::get<int>(args[1]->value());
+
+    return std::make_shared<Constant>(TYPE_STRING,
+                                      std::string(1, str[n]),
+                                      loc);
+  }
 }
diff --git a/libstd/fun.hpp b/libstd/fun.hpp
index 42fb259..fad8a65 100644
--- a/libstd/fun.hpp
+++ b/libstd/fun.hpp
@@ -30,6 +30,10 @@ namespace fkstd
 
   STDRET bool_not(Loc loc, Module& mod, STDARGS args);
   STDRET array_ref(Loc loc, Module& mod, STDARGS args);
+
+  STDRET string_cat(Loc loc, Module& mod, STDARGS args);
+  STDRET string_dup(Loc loc, Module& mod, STDARGS args);
+  STDRET char_at(Loc loc, Module& mod, STDARGS args);
 }
 
 #endif
diff --git a/libstd/lib.cpp b/libstd/lib.cpp
index 24a7648..80bfbfd 100644
--- a/libstd/lib.cpp
+++ b/libstd/lib.cpp
@@ -29,6 +29,9 @@ extern "C" void lib(Module& mod)
 
   mod.register_function("not", fkstd::bool_not);
   mod.register_function("ref", fkstd::array_ref);
+  mod.register_function("cat", fkstd::string_cat);
+  mod.register_function("dup", fkstd::string_dup);
+  mod.register_function("char-at", fkstd::char_at);
 
   mod.register_macro("!", fkstd::set_addr);
   mod.register_macro("assert-static-fail", fkstd::assert_static_fail);