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

diff --git a/src/interpreter/naive_interpreter.nit b/src/interpreter/naive_interpreter.nit
index f7b765b..233d758 100644
--- a/src/interpreter/naive_interpreter.nit
+++ b/src/interpreter/naive_interpreter.nit
@@ -325,7 +325,7 @@ class NaiveInterpreter
 	do
 		var instance = c_string_instance_len(txt.byte_length+1)
 		var val = instance.val
-		val[txt.byte_length] = 0u8
+		val[txt.byte_length] = 0
 		txt.to_cstring.copy_to(val, txt.byte_length, 0, 0)
 
 		return instance
@@ -721,6 +721,10 @@ abstract class Instance
 	# Abort if the instance is not a boolean value.
 	fun is_true: Bool do abort
 
+	# Return `true` if the instance is null.
+	# Return `false` otherwise.
+	fun is_null: Bool do return mtype isa MNullType
+
 	# Return true if `self` IS `o` (using the Nit semantic of is)
 	fun eq_is(o: Instance): Bool do return self.is_same_instance(o)
 
@@ -1189,10 +1193,10 @@ redef class AMethPropdef
 			var recvval = args.first.val.as(CString)
 			if pname == "[]" then
 				var arg1 = args[1].to_i
-				return v.byte_instance(recvval[arg1])
+				return v.int_instance(recvval[arg1])
 			else if pname == "[]=" then
 				var arg1 = args[1].to_i
-				recvval[arg1] = args[2].val.as(Byte)
+				recvval[arg1] = args[2].val.as(Int)
 				return null
 			else if pname == "copy_to" then
 				# sig= copy_to(dest: CString, length: Int, from: Int, to: Int)
@@ -1529,7 +1533,7 @@ redef class AAttrPropdef
 		else if mpropdef == mwritepropdef then
 			assert args.length == 2
 			var arg = args[1]
-			if is_optional and arg.mtype isa MNullType then
+			if is_optional and arg.is_null then
 				var f = v.new_frame(self, mpropdef, args)
 				arg = evaluate_expr(v, recv, f)
 			end
@@ -1824,7 +1828,7 @@ redef class AForExpr
 		for g in n_groups do
 			var col = v.expr(g.n_expr)
 			if col == null then return
-			if col.mtype isa MNullType then fatal(v, "Receiver is null")
+			if col.is_null then fatal(v, "Receiver is null")
 
 			var iter = v.callsite(g.method_iterator, [col]).as(not null)
 			iters.add iter
@@ -1991,8 +1995,9 @@ end
 redef class ACharExpr
 	redef fun expr(v)
 	do
-		if is_ascii then return v.byte_instance(self.value.as(not null).ascii)
-		if is_code_point then return v.int_instance(self.value.as(not null).code_point)
+		if is_code_point then
+			return v.int_instance(self.value.as(not null).code_point)
+		end
 		return v.char_instance(self.value.as(not null))
 	end
 end
@@ -2184,7 +2189,7 @@ redef class AAsNotnullExpr
 	do
 		var i = v.expr(self.n_expr)
 		if i == null then return null
-		if i.mtype isa MNullType then
+		if i.is_null then
 			fatal(v, "Cast failed")
 		end
 		return i
@@ -2217,6 +2222,12 @@ redef class ASendExpr
 	do
 		var recv = v.expr(self.n_expr)
 		if recv == null then return null
+
+		# Safe call shortcut if recv is null
+		if is_safe and recv.is_null then
+			return recv
+		end
+
 		var args = v.varargize(callsite.mpropdef, callsite.signaturemap, recv, self.raw_arguments)
 		if args == null then return null
 
@@ -2313,7 +2324,7 @@ redef class AAttrExpr
 	do
 		var recv = v.expr(self.n_expr)
 		if recv == null then return null
-		if recv.mtype isa MNullType then fatal(v, "Receiver is null")
+		if recv.is_null then fatal(v, "Receiver is null")
 		var mproperty = self.mproperty.as(not null)
 		return v.read_attribute(mproperty, recv)
 	end
@@ -2324,7 +2335,7 @@ redef class AAttrAssignExpr
 	do
 		var recv = v.expr(self.n_expr)
 		if recv == null then return
-		if recv.mtype isa MNullType then fatal(v, "Receiver is null")
+		if recv.is_null then fatal(v, "Receiver is null")
 		var i = v.expr(self.n_value)
 		if i == null then return
 		var mproperty = self.mproperty.as(not null)
@@ -2337,7 +2348,7 @@ redef class AAttrReassignExpr
 	do
 		var recv = v.expr(self.n_expr)
 		if recv == null then return
-		if recv.mtype isa MNullType then fatal(v, "Receiver is null")
+		if recv.is_null then fatal(v, "Receiver is null")
 		var value = v.expr(self.n_value)
 		if value == null then return
 		var mproperty = self.mproperty.as(not null)
@@ -2353,7 +2364,7 @@ redef class AIssetAttrExpr
 	do
 		var recv = v.expr(self.n_expr)
 		if recv == null then return null
-		if recv.mtype isa MNullType then fatal(v, "Receiver is null")
+		if recv.is_null then fatal(v, "Receiver is null")
 		var mproperty = self.mproperty.as(not null)
 		return v.bool_instance(v.isset_attribute(mproperty, recv))
 	end
@@ -2366,6 +2377,13 @@ redef class AVarargExpr
 	end
 end
 
+redef class ASafeExpr
+	redef fun expr(v)
+	do
+		return v.expr(self.n_expr)
+	end
+end
+
 redef class ANamedargExpr
 	redef fun expr(v)
 	do