X-Git-Url: http://nitlanguage.org

diff --git a/lib/standard/kernel.nit b/lib/standard/kernel.nit
index 5cc0547..dfff892 100644
--- a/lib/standard/kernel.nit
+++ b/lib/standard/kernel.nit
@@ -17,10 +17,6 @@ module kernel
 
 import end # Mark this module is a top level one. (must be only one)
 
-`{
-#include <errno.h>
-`}
-
 ###############################################################################
 # System Classes                                                              #
 ###############################################################################
@@ -111,9 +107,7 @@ class Sys
 	fun run do main
 
 	# Number of the last error
-	fun errno: Int is extern `{
-		return errno;
-	`}
+	fun errno: Int is extern "sys_errno"
 end
 
 # Quit the program with a specific return code
@@ -226,6 +220,25 @@ interface Discrete
 	end
 end
 
+# Something that can be cloned
+#
+# This interface introduces the `clone` method used to duplicate an instance
+# Its specific semantic is let to the subclasses.
+interface Cloneable
+	# Duplicate `self`
+	#
+	# The specific semantic of this method is let to the subclasses;
+	# Especially, if (and how) attributes are cloned (depth vs. shallow).
+	#
+	# As a rule of thumb, the principle of least astonishment should
+	# be used to guide the semantic.
+	#
+	# Note that as the returned clone depends on the semantic,
+	# the `==` method, if redefined, should ensure the equality
+	# between an object and its clone.
+	fun clone: SELF is abstract
+end
+
 # A numeric value supporting mathematical operations
 interface Numeric
 	super Comparable
@@ -699,6 +712,22 @@ universal Char
 	do
 		return is_lower or is_upper
 	end
+
+	# Is self a whitespace character?
+	#
+	# These correspond to the "Other" and "Separator" groups of the Unicode.
+	#
+	# In the ASCII encoding, this is those <= to space (0x20) plus delete (0x7F).
+	#
+	#     assert 'A'.is_whitespace  == false
+	#     assert ','.is_whitespace  == false
+	#     assert ' '.is_whitespace  == true
+	#     assert '\t'.is_whitespace == true
+	fun is_whitespace: Bool
+	do
+		var i = ascii
+		return i <= 0x20 or i == 0x7F
+	end
 end
 
 # Pointer classes are used to manipulate extern C structures.