diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/ArrayFunctions.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/ArrayFunctions.java
index 0bae4ca..91b8598 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/ArrayFunctions.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/ArrayFunctions.java
@@ -10,7 +10,7 @@ import com.annimon.ownlang.lib.Value;
 import com.annimon.ownlang.lib.ValueUtils;
 import java.io.UnsupportedEncodingException;
 
-public final class ArrayFunctions {
+final class ArrayFunctions {
     
     private ArrayFunctions() { }
     
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/NumberFunctions.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/NumberFunctions.java
index 2b65451..9bdbd24 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/NumberFunctions.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/NumberFunctions.java
@@ -6,7 +6,7 @@ import com.annimon.ownlang.lib.StringValue;
 import com.annimon.ownlang.lib.Types;
 import com.annimon.ownlang.lib.Value;
 
-public final class NumberFunctions {
+final class NumberFunctions {
 
     private NumberFunctions() { }
 
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/StringFunctions.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/StringFunctions.java
index b89de09..c36ca1b 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/StringFunctions.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/StringFunctions.java
@@ -8,7 +8,7 @@ import com.annimon.ownlang.lib.StringValue;
 import com.annimon.ownlang.lib.Value;
 import java.io.UnsupportedEncodingException;
 
-public final class StringFunctions {
+final class StringFunctions {
 
     private StringFunctions() { }
 
@@ -21,6 +21,11 @@ public final class StringFunctions {
             throw new OwnLangRuntimeException(uee);
         }
     }
+
+    static Value parseDouble(Value[] args) {
+        Arguments.check(1, args.length);
+        return NumberValue.of(Double.parseDouble(args[0].asString()));
+    }
     
     static Value parseInt(Value[] args) {
         Arguments.checkOrOr(1, 2, args.length);
@@ -45,7 +50,7 @@ public final class StringFunctions {
 
         // First blank line is omitted
         final StringBuilder sb = new StringBuilder();
-        final int firstLineIndex = (isBlank(lines[0])) ? 1 : 0;
+        final int firstLineIndex = (lines[0].isBlank()) ? 1 : 0;
         final int lastLineIndex = lines.length - 1;
         int index = firstLineIndex;
         while (true) {
@@ -54,7 +59,7 @@ public final class StringFunctions {
             sb.append('\n');
         }
         // Process last line
-        if (lastLineIndex >= (firstLineIndex + 1) && !isBlank(lines[lastLineIndex])) {
+        if (lastLineIndex >= (firstLineIndex + 1) && !lines[lastLineIndex].isBlank()) {
             sb.append('\n').append(strip(lines[lastLineIndex], marginPrefix));
         }
         return new StringValue(sb.toString());
@@ -68,10 +73,6 @@ public final class StringFunctions {
             return str;
         }
     }
-
-    private static boolean isBlank(String str) {
-        return firstNonBlankIndex(str) == str.length();
-    }
     
     private static int firstNonBlankIndex(String str) {
         final int length = str.length();
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/SystemFunctions.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/SystemFunctions.java
new file mode 100644
index 0000000..9c8f7a3
--- /dev/null
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/SystemFunctions.java
@@ -0,0 +1,42 @@
+package com.annimon.ownlang.modules.std;
+
+import com.annimon.ownlang.lib.*;
+
+final class SystemFunctions {
+
+    private SystemFunctions() { }
+
+    static Value exit(Value[] args) {
+        Arguments.check(1, args.length);
+        System.exit(args[0].asInt());
+        return NumberValue.ZERO;
+    }
+
+    static Value getenv(Value[] args) {
+        Arguments.checkOrOr(1, 2, args.length);
+        final var env = System.getenv(args[0].asString());
+        if (env == null) {
+            return args.length == 2 ? args[1] : StringValue.EMPTY;
+        }
+        return new StringValue(env);
+    }
+
+    static Value getprop(Value[] args) {
+        Arguments.checkOrOr(1, 2, args.length);
+        final var env = System.getProperty(args[0].asString());
+        if (env == null) {
+            return args.length == 2 ? args[1] : StringValue.EMPTY;
+        }
+        return new StringValue(env);
+    }
+
+    static Value time(Value[] args) {
+        Arguments.check(0, args.length);
+        return NumberValue.of(System.currentTimeMillis());
+    }
+
+    static Value nanotime(Value[] args) {
+        Arguments.check(0, args.length);
+        return NumberValue.of(System.nanoTime());
+    }
+}
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std.java
index fe76b58..c3fafa0 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std.java
@@ -4,6 +4,7 @@ import com.annimon.ownlang.Shared;
 import com.annimon.ownlang.Version;
 import com.annimon.ownlang.lib.*;
 import com.annimon.ownlang.modules.Module;
+import java.util.HashMap;
 import java.util.Map;
 import static java.util.Map.entry;
 
@@ -30,22 +31,31 @@ public final class std implements Module {
 
     @Override
     public Map<String, Function> functions() {
-        return Map.ofEntries(
+        // std, System
+        final var result = new HashMap<>(Map.ofEntries(
                 entry("echo", new std_echo()),
                 entry("readln", new std_readln()),
                 entry("length", new std_length()),
                 entry("rand", new std_rand()),
-                entry("time", new std_time()),
+                entry("time", SystemFunctions::time),
+                entry("nanotime", SystemFunctions::nanotime),
                 entry("sleep", new std_sleep()),
                 entry("thread", new std_thread()),
                 entry("sync", new std_sync()),
                 entry("try", new std_try()),
                 entry("default", new std_default()),
+                entry("exit", SystemFunctions::exit),
+                entry("getenv", SystemFunctions::getenv),
+                entry("getprop", SystemFunctions::getprop)
+        ));
 
-                // Numbers
-                entry("toHexString", NumberFunctions::toHexString),
+        // Numbers
+        result.putAll(Map.ofEntries(
+                entry("toHexString", NumberFunctions::toHexString)
+        ));
 
-                // String
+        // String
+        result.putAll(Map.ofEntries(
                 entry("getBytes", StringFunctions::getBytes),
                 entry("sprintf", new std_sprintf()),
                 entry("split", new std_split()),
@@ -62,9 +72,12 @@ public final class std implements Module {
                 entry("replaceFirst", new std_replacefirst()),
                 entry("parseInt", StringFunctions::parseInt),
                 entry("parseLong", StringFunctions::parseLong),
-                entry("stripMargin", StringFunctions::stripMargin),
+                entry("parseDouble", StringFunctions::parseDouble),
+                entry("stripMargin", StringFunctions::stripMargin)
+        ));
 
-                // Arrays and map,
+        // Arrays and map
+        result.putAll(Map.ofEntries(
                 entry("newarray", new std_newarray()),
                 entry("join", new std_join()),
                 entry("sort", new std_sort()),
@@ -75,6 +88,7 @@ public final class std implements Module {
                 entry("arraySplice", new std_arraySplice()),
                 entry("range", new std_range()),
                 entry("stringFromBytes", ArrayFunctions::stringFromBytes)
-        );
+        ));
+        return Map.copyOf(result);
     }
 }
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayCombine.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayCombine.java
index d9a32a4..78a4837 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayCombine.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayCombine.java
@@ -8,7 +8,7 @@ import com.annimon.ownlang.lib.MapValue;
 import com.annimon.ownlang.lib.Types;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_arrayCombine implements Function {
+final class std_arrayCombine implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayKeyExists.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayKeyExists.java
index fb4b241..51eff70 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayKeyExists.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayKeyExists.java
@@ -8,7 +8,7 @@ import com.annimon.ownlang.lib.NumberValue;
 import com.annimon.ownlang.lib.Types;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_arrayKeyExists implements Function {
+final class std_arrayKeyExists implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayKeys.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayKeys.java
index e2f1565..2bd2e47 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayKeys.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayKeys.java
@@ -11,7 +11,7 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 
-public final class std_arrayKeys implements Function {
+final class std_arrayKeys implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arraySplice.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arraySplice.java
index 2614bc2..daf6870 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arraySplice.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arraySplice.java
@@ -7,7 +7,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.Types;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_arraySplice implements Function {
+final class std_arraySplice implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayValues.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayValues.java
index f263d0f..1a7de75 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayValues.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_arrayValues.java
@@ -11,7 +11,7 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 
-public final class std_arrayValues implements Function {
+final class std_arrayValues implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_charat.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_charat.java
index de0407a..35b8ba1 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_charat.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_charat.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.NumberValue;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_charat implements Function {
+final class std_charat implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_default.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_default.java
index 76b96ad..f2d3a81 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_default.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_default.java
@@ -1,13 +1,8 @@
 package com.annimon.ownlang.modules.std;
 
-import com.annimon.ownlang.lib.Arguments;
-import com.annimon.ownlang.lib.ArrayValue;
-import com.annimon.ownlang.lib.Function;
-import com.annimon.ownlang.lib.MapValue;
-import com.annimon.ownlang.lib.Types;
-import com.annimon.ownlang.lib.Value;
+import com.annimon.ownlang.lib.*;
 
-public final class std_default implements Function {
+final class std_default implements Function {
 
     @Override
     public Value execute(Value[] args) {
@@ -22,17 +17,13 @@ public final class std_default implements Function {
         if (value == null || value.raw() == null) {
             return true;
         }
-        switch (value.type()) {
-            case Types.NUMBER:
-                return (value.asInt() == 0);
-            case Types.STRING:
-                return (value.asString().isEmpty());
-            case Types.ARRAY:
-                return ((ArrayValue) value).size() == 0;
-            case Types.MAP:
-                return ((MapValue) value).size() == 0;
-            default:
-                return false;
-        }
+        return switch (value.type()) {
+            case Types.NUMBER -> (value.asInt() == 0);
+            case Types.STRING -> (value.asString().isEmpty());
+            case Types.ARRAY -> ((ArrayValue) value).size() == 0;
+            case Types.MAP -> ((MapValue) value).size() == 0;
+            case Types.CLASS -> ((ClassInstance) value).getThisMap().size() == 0;
+            default -> false;
+        };
     }
 }
\ No newline at end of file
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_echo.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_echo.java
index 27bdfb6..3c4e68b 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_echo.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_echo.java
@@ -5,14 +5,14 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.NumberValue;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_echo implements Function {
+final class std_echo implements Function {
 
     @Override
     public Value execute(Value[] args) {
         final StringBuilder sb = new StringBuilder();
         for (Value arg : args) {
             sb.append(arg.asString());
-            sb.append(" ");
+            sb.append(' ');
         }
         Console.println(sb.toString());
         return NumberValue.ZERO;
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_indexof.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_indexof.java
index 5b9e1db..6168042 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_indexof.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_indexof.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.NumberValue;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_indexof implements Function {
+final class std_indexof implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_join.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_join.java
index 7806c93..033ac1c 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_join.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_join.java
@@ -8,7 +8,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.Types;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_join implements Function {
+final class std_join implements Function {
 
     @Override
     public Value execute(Value[] args) {
@@ -18,17 +18,12 @@ public final class std_join implements Function {
         }
         
         final ArrayValue array = (ArrayValue) args[0];
-        switch (args.length) {
-            case 1:
-                return ArrayValue.joinToString(array, "", "", "");
-            case 2:
-                return ArrayValue.joinToString(array, args[1].asString(), "", "");
-            case 3:
-                return ArrayValue.joinToString(array, args[1].asString(), args[2].asString(), args[2].asString());
-            case 4:
-                return ArrayValue.joinToString(array, args[1].asString(), args[2].asString(), args[3].asString());
-            default:
-                throw new ArgumentsMismatchException("Wrong number of arguments");
-        }
+        return switch (args.length) {
+            case 1 -> ArrayValue.joinToString(array, "", "", "");
+            case 2 -> ArrayValue.joinToString(array, args[1].asString(), "", "");
+            case 3 -> ArrayValue.joinToString(array, args[1].asString(), args[2].asString(), args[2].asString());
+            case 4 -> ArrayValue.joinToString(array, args[1].asString(), args[2].asString(), args[3].asString());
+            default -> throw new ArgumentsMismatchException("Wrong number of arguments");
+        };
     }
 }
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_lastindexof.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_lastindexof.java
index b412466..ab60e3a 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_lastindexof.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_lastindexof.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.NumberValue;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_lastindexof implements Function {
+final class std_lastindexof implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_length.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_length.java
index 67487ce..5e58b50 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_length.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_length.java
@@ -2,32 +2,24 @@ package com.annimon.ownlang.modules.std;
 
 import com.annimon.ownlang.lib.*;
 
-public final class std_length implements Function {
+final class std_length implements Function {
 
     @Override
     public Value execute(Value[] args) {
         Arguments.check(1, args.length);
 
-        final Value val = args[0];
-        final int length;
-        switch (val.type()) {
-            case Types.ARRAY:
-                length = ((ArrayValue) val).size();
-                break;
-            case Types.MAP:
-                length = ((MapValue) val).size();
-                break;
-            case Types.STRING:
-                length = ((StringValue) val).length();
-                break;
-            case Types.FUNCTION:
-                final Function func = ((FunctionValue) val).getValue();
-                length = func.getArgsCount();
-                break;
-            default:
-                length = 0;
-                
-        }
+        final Value value = args[0];
+        final int length = switch (value.type()) {
+            case Types.ARRAY -> ((ArrayValue) value).size();
+            case Types.MAP -> ((MapValue) value).size();
+            case Types.CLASS -> ((ClassInstance) value).getThisMap().size();
+            case Types.STRING -> ((StringValue) value).length();
+            case Types.FUNCTION -> {
+                final Function func = ((FunctionValue) value).getValue();
+                yield func.getArgsCount();
+            }
+            default -> 0;
+        };
         return NumberValue.of(length);
     }
 }
\ No newline at end of file
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_newarray.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_newarray.java
index 78029e9..33c1b4d 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_newarray.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_newarray.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.NumberValue;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_newarray implements Function {
+final class std_newarray implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_rand.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_rand.java
index 5696253..0888abc 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_rand.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_rand.java
@@ -6,7 +6,7 @@ import com.annimon.ownlang.lib.NumberValue;
 import com.annimon.ownlang.lib.Value;
 import java.util.Random;
 
-public final class std_rand implements Function {
+final class std_rand implements Function {
 
     private static final Random RND = new Random();
 
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_range.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_range.java
index a7336ae..1feb1b9 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_range.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_range.java
@@ -3,32 +3,16 @@ package com.annimon.ownlang.modules.std;
 import com.annimon.ownlang.lib.*;
 import java.util.Iterator;
 
-public final class std_range implements Function {
+final class std_range implements Function {
 
     @Override
     public Value execute(Value[] args) {
         Arguments.checkRange(1, 3, args.length);
-
-        final long from, to, step;
-        switch (args.length) {
-            default:
-            case 1:
-                from = 0;
-                to = getLong(args[0]);
-                step = 1;
-                break;
-            case 2:
-                from = getLong(args[0]);
-                to = getLong(args[1]);
-                step = 1;
-                break;
-            case 3:
-                from = getLong(args[0]);
-                to = getLong(args[1]);
-                step = getLong(args[2]);
-                break;
-        }
-        return RangeValue.of(from, to, step);
+        return switch (args.length) {
+            default -> RangeValue.of(0, getLong(args[0]), 1);
+            case 2 -> RangeValue.of(getLong(args[0]), getLong(args[1]), 1);
+            case 3 -> RangeValue.of(getLong(args[0]), getLong(args[1]), getLong(args[2]));
+        };
     }
 
     private static long getLong(Value v) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_readln.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_readln.java
index 50605e7..703f789 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_readln.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_readln.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.StringValue;
 import com.annimon.ownlang.lib.Value;
 import java.util.Scanner;
 
-public final class std_readln implements Function {
+final class std_readln implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_replace.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_replace.java
index 8a274a1..aee1dd5 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_replace.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_replace.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.StringValue;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_replace implements Function {
+final class std_replace implements Function {
     
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_replaceall.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_replaceall.java
index 6e3c283..74e425d 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_replaceall.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_replaceall.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.StringValue;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_replaceall implements Function {
+final class std_replaceall implements Function {
     
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_replacefirst.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_replacefirst.java
index c02e554..04ba373 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_replacefirst.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_replacefirst.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.StringValue;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_replacefirst implements Function {
+final class std_replacefirst implements Function {
     
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sleep.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sleep.java
index f0742aa..9d01de1 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sleep.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sleep.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.NumberValue;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_sleep implements Function {
+final class std_sleep implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sort.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sort.java
index 6735fc7..adb6728 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sort.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sort.java
@@ -10,7 +10,7 @@ import com.annimon.ownlang.lib.Value;
 import com.annimon.ownlang.lib.ValueUtils;
 import java.util.Arrays;
 
-public final class std_sort implements Function {
+final class std_sort implements Function {
 
     @Override
     public Value execute(Value[] args) {
@@ -19,17 +19,14 @@ public final class std_sort implements Function {
             throw new TypeException("Array expected in first argument");
         }
         final Value[] elements = ((ArrayValue) args[0]).getCopyElements();
-        
+
         switch (args.length) {
-            case 1:
-                Arrays.sort(elements);
-                break;
-            case 2:
+            case 1 -> Arrays.sort(elements);
+            case 2 -> {
                 final Function comparator = ValueUtils.consumeFunction(args[1], 1);
                 Arrays.sort(elements, (o1, o2) -> comparator.execute(o1, o2).asInt());
-                break;
-            default:
-                throw new ArgumentsMismatchException("Wrong number of arguments");
+            }
+            default -> throw new ArgumentsMismatchException("Wrong number of arguments");
         }
         
         return new ArrayValue(elements);
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_split.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_split.java
index 7b2c5a1..73aa73f 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_split.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_split.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.ArrayValue;
 import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_split implements Function {
+final class std_split implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sprintf.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sprintf.java
index 5dfdb11..944f640 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sprintf.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sprintf.java
@@ -6,7 +6,7 @@ import com.annimon.ownlang.lib.StringValue;
 import com.annimon.ownlang.lib.Types;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_sprintf implements Function {
+final class std_sprintf implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_substring.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_substring.java
index dcae235..84f769e 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_substring.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_substring.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.StringValue;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_substring implements Function {
+final class std_substring implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sync.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sync.java
index 2c91c82..04a4d31 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sync.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_sync.java
@@ -10,7 +10,7 @@ import com.annimon.ownlang.lib.ValueUtils;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.LinkedBlockingQueue;
 
-public final class std_sync implements Function {
+final class std_sync implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_thread.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_thread.java
index d4ece89..ca36114 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_thread.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_thread.java
@@ -3,7 +3,7 @@ package com.annimon.ownlang.modules.std;
 import com.annimon.ownlang.Console;
 import com.annimon.ownlang.lib.*;
 
-public final class std_thread implements Function {
+final class std_thread implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_time.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_time.java
deleted file mode 100644
index f5fc062..0000000
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_time.java
+++ /dev/null
@@ -1,13 +0,0 @@
-package com.annimon.ownlang.modules.std;
-
-import com.annimon.ownlang.lib.Function;
-import com.annimon.ownlang.lib.NumberValue;
-import com.annimon.ownlang.lib.Value;
-
-public final class std_time implements Function {
-
-    @Override
-    public Value execute(Value[] args) {
-        return NumberValue.of(System.currentTimeMillis());
-    }
-}
\ No newline at end of file
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_tochar.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_tochar.java
index b59bc0d..d052cf8 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_tochar.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_tochar.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.StringValue;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_tochar implements Function {
+final class std_tochar implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_tolowercase.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_tolowercase.java
index f27fe01..813f78d 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_tolowercase.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_tolowercase.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.StringValue;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_tolowercase implements Function {
+final class std_tolowercase implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_touppercase.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_touppercase.java
index e59397c..74c071c 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_touppercase.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_touppercase.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.StringValue;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_touppercase implements Function {
+final class std_touppercase implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_trim.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_trim.java
index de57bbc..7ee1cba 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_trim.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_trim.java
@@ -5,7 +5,7 @@ import com.annimon.ownlang.lib.Function;
 import com.annimon.ownlang.lib.StringValue;
 import com.annimon.ownlang.lib.Value;
 
-public final class std_trim implements Function {
+final class std_trim implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_try.java b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_try.java
index 8546119..bf37ae4 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_try.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/std/std_try.java
@@ -2,7 +2,7 @@ package com.annimon.ownlang.modules.std;
 
 import com.annimon.ownlang.lib.*;
 
-public final class std_try implements Function {
+final class std_try implements Function {
 
     @Override
     public Value execute(Value[] args) {
diff --git a/modules/main/src/main/java/com/annimon/ownlang/modules/types/types.java b/modules/main/src/main/java/com/annimon/ownlang/modules/types/types.java
index 613080a..5a84570 100644
--- a/modules/main/src/main/java/com/annimon/ownlang/modules/types/types.java
+++ b/modules/main/src/main/java/com/annimon/ownlang/modules/types/types.java
@@ -19,7 +19,8 @@ public final class types implements Module {
                 entry("STRING", NumberValue.of(Types.STRING)),
                 entry("ARRAY", NumberValue.of(Types.ARRAY)),
                 entry("MAP", NumberValue.of(Types.MAP)),
-                entry("FUNCTION", NumberValue.of(Types.FUNCTION))
+                entry("FUNCTION", NumberValue.of(Types.FUNCTION)),
+                entry("CLASS", NumberValue.of(Types.CLASS))
         );
     }