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

diff --git a/src/naive_interpreter.nit b/src/naive_interpreter.nit
index cc5455f..510d0a0 100644
--- a/src/naive_interpreter.nit
+++ b/src/naive_interpreter.nit
@@ -20,10 +20,23 @@ module naive_interpreter
 import literal
 import typing
 import auto_super_init
+import frontend
+import common_ffi
+
+redef class ToolContext
+	# --discover-call-trace
+	var opt_discover_call_trace: OptionBool = new OptionBool("Trace calls of the first invocation of a method", "--discover-call-trace")
+
+	redef init
+	do
+		super
+		self.option_context.add_option(self.opt_discover_call_trace)
+	end
+end
 
 redef class ModelBuilder
-	# Execute the program from the entry point (Sys::main) of the `mainmodule'
-	# `arguments' are the command-line arguments in order
+	# Execute the program from the entry point (`Sys::main`) of the `mainmodule`
+	# `arguments` are the command-line arguments in order
 	# REQUIRE that:
 	#   1. the AST is fully loaded.
 	#   2. the model is fully built.
@@ -34,23 +47,26 @@ redef class ModelBuilder
 		self.toolcontext.info("*** START INTERPRETING ***", 1)
 
 		var interpreter = new NaiveInterpreter(self, mainmodule, arguments)
+		init_naive_interpreter(interpreter, mainmodule)
+
+		var time1 = get_time
+		self.toolcontext.info("*** END INTERPRETING: {time1-time0} ***", 2)
+	end
+
+	private fun init_naive_interpreter(interpreter: NaiveInterpreter, mainmodule: MModule) do
 		var sys_type = mainmodule.sys_type
 		if sys_type == null then return # no class Sys
-		var mainobj = new Instance(sys_type)
+		var mainobj = new MutableInstance(sys_type)
 		interpreter.mainobj = mainobj
 		interpreter.init_instance(mainobj)
-		var initprop = mainmodule.try_get_primitive_method("init", sys_type)
+		var initprop = mainmodule.try_get_primitive_method("init", sys_type.mclass)
 		if initprop != null then
 			interpreter.send(initprop, [mainobj])
 		end
-		interpreter.check_init_instance(mainobj)
-		var mainprop = mainmodule.try_get_primitive_method("main", sys_type)
+		var mainprop = mainmodule.try_get_primitive_method("main", sys_type.mclass)
 		if mainprop != null then
 			interpreter.send(mainprop, [mainobj])
 		end
-
-		var time1 = get_time
-		self.toolcontext.info("*** END INTERPRETING: {time1-time0} ***", 2)
 	end
 end
 
@@ -76,7 +92,7 @@ private class NaiveInterpreter
 		self.arguments = arguments
 		self.true_instance = new PrimitiveInstance[Bool](mainmodule.bool_type, true)
 		self.false_instance = new PrimitiveInstance[Bool](mainmodule.bool_type, false)
-		self.null_instance = new Instance(mainmodule.model.null_type)
+		self.null_instance = new MutableInstance(mainmodule.model.null_type)
 	end
 
 	# Subtype test in the context of the mainmodule
@@ -85,16 +101,22 @@ private class NaiveInterpreter
 		return sub.is_subtype(self.mainmodule, self.frame.arguments.first.mtype.as(MClassType), sup)
 	end
 
+	fun force_get_primitive_method(name: String, recv: MType): MMethod
+	do
+		assert recv isa MClassType
+		return self.modelbuilder.force_get_primitive_method(self.frame.current_node, name, recv.mclass, self.mainmodule)
+	end
+
 	# Is a return executed?
 	# Set this mark to skip the evaluation until the end of the specified method frame
 	var returnmark: nullable Frame = null
 
 	# Is a break executed?
-	# Set this mark to skip the evaluation until a labeled statement catch it with `is_break'
+	# Set this mark to skip the evaluation until a labeled statement catch it with `is_break`
 	var breakmark: nullable EscapeMark = null
 
 	# Is a continue executed?
-	# Set this mark to skip the evaluation until a labeled statement catch it with `is_continue'
+	# Set this mark to skip the evaluation until a labeled statement catch it with `is_continue`
 	var continuemark: nullable EscapeMark = null
 
 	# Is a return or a break or a continue executed?
@@ -106,8 +128,8 @@ private class NaiveInterpreter
 	# Read the value when you catch a mark or reach the end of a method
 	var escapevalue: nullable Instance = null
 
-	# If there is a break and is associated with `escapemark', then return true an clear the mark.
-	# If there is no break or if `escapemark' is null then return false.
+	# If there is a break and is associated with `escapemark`, then return true an clear the mark.
+	# If there is no break or if `escapemark` is null then return false.
 	# Use this function to catch a potential break.
 	fun is_break(escapemark: nullable EscapeMark): Bool
 	do
@@ -119,8 +141,8 @@ private class NaiveInterpreter
 		end
 	end
 
-	# If there is a continue and is associated with `escapemark', then return true an clear the mark.
-	# If there is no continue or if `escapemark' is null then return false.
+	# If there is a continue and is associated with `escapemark`, then return true an clear the mark.
+	# If there is no continue or if `escapemark` is null then return false.
 	# Use this function to catch a potential continue.
 	fun is_continue(escapemark: nullable EscapeMark): Bool
 	do
@@ -132,9 +154,9 @@ private class NaiveInterpreter
 		end
 	end
 
-	# Evaluate `n' as an expression in the current context.
+	# Evaluate `n` as an expression in the current context.
 	# Return the value of the expression.
-	# If `n' cannot be evaluated, then aborts.
+	# If `n` cannot be evaluated, then aborts.
 	fun expr(n: AExpr): nullable Instance
 	do
 		var frame = self.frame
@@ -145,15 +167,21 @@ private class NaiveInterpreter
 		if i == null and not self.is_escaping then
 			n.debug("inconsitance: no value and not escaping.")
 		end
+		var implicit_cast_to = n.implicit_cast_to
+		if implicit_cast_to != null then
+			var mtype = self.unanchor_type(implicit_cast_to)
+			if not self.is_subtype(i.mtype, mtype) then n.fatal(self, "Cast failed. Expected `{implicit_cast_to}`, got `{i.mtype}`")
+		end
+
 		#n.debug("OUT Execute expr: value is {i}")
 		#if not is_subtype(i.mtype, n.mtype.as(not null)) then n.debug("Expected {n.mtype.as(not null)} got {i}")
 		frame.current_node = old
 		return i
 	end
 
-	# Evaluate `n' as a statement in the current context.
-	# Do nothing if `n' is sull.
-	# If `n' cannot be evaluated, then aborts.
+	# Evaluate `n` as a statement in the current context.
+	# Do nothing if `n` is null.
+	# If `n` cannot be evaluated, then aborts.
 	fun stmt(n: nullable AExpr)
 	do
 		if n != null then
@@ -166,63 +194,62 @@ private class NaiveInterpreter
 		end
 	end
 
-	# Map used to store values of nodes that must be evaluated once in the system (AOnceExpr)
+	# Map used to store values of nodes that must be evaluated once in the system (`AOnceExpr`)
 	var onces: Map[ANode, Instance] = new HashMap[ANode, Instance]
 
-	# Return the boolean instance associated with `val'.
+	# Return the boolean instance associated with `val`.
 	fun bool_instance(val: Bool): Instance
 	do
 		if val then return self.true_instance else return self.false_instance
 	end
 
-	# Return the integer instance associated with `val'.
+	# Return the integer instance associated with `val`.
 	fun int_instance(val: Int): Instance
 	do
 		var ic = self.mainmodule.get_primitive_class("Int")
 		return new PrimitiveInstance[Int](ic.mclass_type, val)
 	end
 
-	# Return the char instance associated with `val'.
+	# Return the char instance associated with `val`.
 	fun char_instance(val: Char): Instance
 	do
 		var ic = self.mainmodule.get_primitive_class("Char")
 		return new PrimitiveInstance[Char](ic.mclass_type, val)
 	end
 
-	# Return the float instance associated with `val'.
+	# Return the float instance associated with `val`.
 	fun float_instance(val: Float): Instance
 	do
 		var ic = self.mainmodule.get_primitive_class("Float")
 		return new PrimitiveInstance[Float](ic.mclass_type, val)
 	end
 
-	# The unique intance of the `true' value.
+	# The unique intance of the `true` value.
 	var true_instance: Instance
 
-	# The unique intance of the `false' value.
+	# The unique intance of the `false` value.
 	var false_instance: Instance
 
-	# The unique intance of the `null' value.
+	# The unique intance of the `null` value.
 	var null_instance: Instance
 
-	# Return a new array made of `values'.
+	# Return a new array made of `values`.
 	# The dynamic type of the result is Array[elttype].
 	fun array_instance(values: Array[Instance], elttype: MType): Instance
 	do
 		assert not elttype.need_anchor
 		var nat = new PrimitiveInstance[Array[Instance]](self.mainmodule.get_primitive_class("NativeArray").get_mtype([elttype]), values)
 		var mtype = self.mainmodule.get_primitive_class("Array").get_mtype([elttype])
-		var res = new Instance(mtype)
+		var res = new MutableInstance(mtype)
 		self.init_instance(res)
-		self.send(self.mainmodule.force_get_primitive_method("with_native", mtype), [res, nat, self.int_instance(values.length)])
-		self.check_init_instance(res)
+		self.send(self.force_get_primitive_method("with_native", mtype), [res, nat, self.int_instance(values.length)])
 		return res
 	end
 
-	# Return a new native string initialized with `txt'
+	# Return a new native string initialized with `txt`
 	fun native_string_instance(txt: String): Instance
 	do
-		var val = new Buffer.from(txt)
+		var val = new FlatBuffer.from(txt)
 		val.add('\0')
 		var ic = self.mainmodule.get_primitive_class("NativeString")
 		return new PrimitiveInstance[Buffer](ic.mclass_type, val)
@@ -237,7 +264,7 @@ private class NaiveInterpreter
 	# Return a stack stace. One line per function
 	fun stack_trace: String
 	do
-		var b = new Buffer
+		var b = new FlatBuffer
 		b.append(",---- Stack trace -- - -  -\n")
 		for f in frames do
 			b.append("| {f.mpropdef} ({f.current_node.location})\n")
@@ -257,10 +284,21 @@ private class NaiveInterpreter
 		exit(1)
 	end
 
-	# Execute `mpropdef' for a `args' (where args[0] is the receiver).
-	# Return a falue if `mpropdef' is a function, or null if it is a procedure.
-	# The call is direct/static. There is no message-seding/late-bindng.
-	fun call(mpropdef: MMethodDef, args: Array[Instance]): nullable Instance
+	# Debug on the current node
+	fun debug(message: String)
+	do
+		if frames.is_empty then
+			print message
+		else
+			self.frame.current_node.debug(message)
+		end
+	end
+
+	# Store known method, used to trace methods as thez are reached
+	var discover_call_trace: Set[MMethodDef] = new HashSet[MMethodDef]
+
+	# Common code for calls to injected methods and normal methods
+	fun call_commons(mpropdef: MMethodDef, args: Array[Instance]): Array[Instance]
 	do
 		var vararg_rank = mpropdef.msignature.vararg_rank
 		if vararg_rank >= 0 then
@@ -287,15 +325,39 @@ private class NaiveInterpreter
 				args.add(rawargs[i+1])
 			end
 		end
-		#assert args.length == mpropdef.msignature.arity + 1 # because of self
+		return args
+	end
+
+	# Execute `mpropdef` for a `args` (where `args[0]` is the receiver).
+	# Return a falue if `mpropdef` is a function, or null if it is a procedure.
+	# The call is direct/static. There is no message-seding/late-binding.
+	fun call(mpropdef: MMethodDef, args: Array[Instance]): nullable Instance
+	do
+		args = call_commons(mpropdef, args)
+		return call_without_varargs(mpropdef, args)
+	end
+
+	# Common code to call and this function
+	#
+	# Call only executes the variadic part, this avoids
+	# double encapsulation of variadic parameters into an Array
+	fun call_without_varargs(mpropdef: MMethodDef, args: Array[Instance]): nullable Instance
+	do
+		if self.modelbuilder.toolcontext.opt_discover_call_trace.value and not self.discover_call_trace.has(mpropdef) then
+			self.discover_call_trace.add mpropdef
+			self.debug("Discovered {mpropdef}")
+		end
+		assert args.length == mpropdef.msignature.arity + 1 else debug("Invalid arity for {mpropdef}. {args.length} arguments given.")
 
 		# Look for the AST node that implements the property
 		var mproperty = mpropdef.mproperty
 		if self.modelbuilder.mpropdef2npropdef.has_key(mpropdef) then
 			var npropdef = self.modelbuilder.mpropdef2npropdef[mpropdef]
+			self.parameter_check(npropdef, mpropdef, args)
 			return npropdef.call(self, mpropdef, args)
 		else if mproperty.name == "init" then
 			var nclassdef = self.modelbuilder.mclassdef2nclassdef[mpropdef.mclassdef]
+			self.parameter_check(nclassdef, mpropdef, args)
 			return nclassdef.call(self, mpropdef, args)
 		else
 			fatal("Fatal Error: method {mpropdef} not found in the AST")
@@ -303,63 +365,68 @@ private class NaiveInterpreter
 		end
 	end
 
-	fun call_closure(closure: ClosureInstance, args: Array[Instance]): nullable Instance
+	# Generate type checks in the C code to check covariant parameters
+	fun parameter_check(node: ANode, mpropdef: MMethodDef, args: Array[Instance])
 	do
-		var nclosuredef = closure.nclosuredef
-		var f = closure.frame
-		for i in [0..closure.nclosuredef.mclosure.mtype.as(MSignature).arity[ do
-			var variable = nclosuredef.variables[i]
-			f.map[variable] = args[i]
-		end
-
-		self.frames.unshift(f)
-
-		self.stmt(nclosuredef.n_expr)
+		var msignature = mpropdef.msignature
+		for i in [0..msignature.arity[ do
+			# skip test for vararg since the array is instantiated with the correct polymorphic type
+			if msignature.vararg_rank == i then continue
 
-		self.frames.shift
+			# skip if the cast is not required
+			var origmtype =  mpropdef.mproperty.intro.msignature.mparameters[i].mtype
+			if not origmtype.need_anchor then continue
 
-		if self.is_continue(nclosuredef.escapemark) then
-			var res = self.escapevalue
-			self.escapevalue = null
-			return res
+			# get the parameter type
+			var mtype = msignature.mparameters[i].mtype
+			var anchor = args.first.mtype.as(MClassType)
+			var amtype = mtype.anchor_to(self.mainmodule, anchor)
+			if not args[i+1].mtype.is_subtype(self.mainmodule, anchor, amtype) then
+				node.fatal(self, "Cast failed. Expected `{mtype}`, got `{args[i+1].mtype}`")
+			end
 		end
-		return null
 	end
 
-	# Execute `mproperty' for a `args' (where args[0] is the receiver).
-	# Return a falue if `mproperty' is a function, or null if it is a procedure.
-	# The call is polimotphic. There is a message-seding/late-bindng according to te receiver (args[0]).
-	fun send(mproperty: MMethod, args: Array[Instance]): nullable Instance
+	# Common code for runtime injected calls and normal calls
+	fun send_commons(mproperty: MMethod, args: Array[Instance], mtype: MType): nullable Instance
 	do
-		var recv = args.first
-		var mtype = recv.mtype
 		if mtype isa MNullType then
 			if mproperty.name == "==" then
 				return self.bool_instance(args[0] == args[1])
 			else if mproperty.name == "!=" then
 				return self.bool_instance(args[0] != args[1])
 			end
-			#fatal("Reciever is null. {mproperty}. {args.join(" ")} {self.frame.current_node.class_name}")
-			fatal("Reciever is null")
-			abort
-		end
-		var propdefs = mproperty.lookup_definitions(self.mainmodule, mtype)
-		if propdefs.length > 1 then
-			fatal("NOT YET IMPLEMETED ERROR: Property conflict: {propdefs.join(", ")}")
-			abort
+			#fatal("Receiver is null. {mproperty}. {args.join(" ")} {self.frame.current_node.class_name}")
+			fatal("Receiver is null")
 		end
-		assert propdefs.length == 1 else
-			fatal("Fatal Error: No property '{mproperty}' for '{recv}'")
-			abort
-		end
-		var propdef = propdefs.first
+		return null
+	end
+
+	# Execute a full `callsite` for given `args`
+	# Use this method, instead of `send` to execute and control the aditionnal behavior of the call-sites
+	fun callsite(callsite: nullable CallSite, arguments: Array[Instance]): nullable Instance
+	do
+		return send(callsite.mproperty, arguments)
+	end
+
+	# Execute `mproperty` for a `args` (where `args[0]` is the receiver).
+	# Return a falue if `mproperty` is a function, or null if it is a procedure.
+	# The call is polimotphic. There is a message-seding/late-bindng according to te receiver (args[0]).
+	fun send(mproperty: MMethod, args: Array[Instance]): nullable Instance
+	do
+		var recv = args.first
+		var mtype = recv.mtype
+		var ret = send_commons(mproperty, args, mtype)
+		if ret != null then return ret
+		var propdef = mproperty.lookup_first_definition(self.mainmodule, mtype)
 		return self.call(propdef, args)
 	end
 
-	# Read the attribute `mproperty' of an instance `recv' and return its value.
+	# Read the attribute `mproperty` of an instance `recv` and return its value.
 	# If the attribute in not yet initialized, then aborts with an error message.
 	fun read_attribute(mproperty: MAttribute, recv: Instance): Instance
 	do
+		assert recv isa MutableInstance
 		if not recv.attributes.has_key(mproperty) then
 			fatal("Uninitialized attribute {mproperty.name}")
 			abort
@@ -367,35 +434,36 @@ private class NaiveInterpreter
 		return recv.attributes[mproperty]
 	end
 
-	# Fill the initial values of the newly created instance `recv'.
-	# `recv.mtype' is used to know what must be filled.
-	fun init_instance(recv: Instance)
+	# Collect attributes of a type in the order of their init
+	fun collect_attr_propdef(mtype: MType): Array[AAttrPropdef]
 	do
-		for cd in recv.mtype.collect_mclassdefs(self.mainmodule)
-		do
+		var cache = self.collect_attr_propdef_cache
+		if cache.has_key(mtype) then return cache[mtype]
+
+		var res = new Array[AAttrPropdef]
+		var cds = mtype.collect_mclassdefs(self.mainmodule).to_a
+		self.mainmodule.linearize_mclassdefs(cds)
+		for cd in cds do
 			var n = self.modelbuilder.mclassdef2nclassdef[cd]
 			for npropdef in n.n_propdefs do
 				if npropdef isa AAttrPropdef then
-					npropdef.init_expr(self, recv)
+					res.add(npropdef)
 				end
 			end
 		end
+
+		cache[mtype] = res
+		return res
 	end
 
-	# Check that non nullable attributes of `recv' are correctly initialized.
-	# This function is used as the last instruction of a new
-	# FIXME: this will work better once there is nullable types
-	fun check_init_instance(recv: Instance)
+	var collect_attr_propdef_cache = new HashMap[MType, Array[AAttrPropdef]]
+
+	# Fill the initial values of the newly created instance `recv`.
+	# `recv.mtype` is used to know what must be filled.
+	fun init_instance(recv: Instance)
 	do
-		for cd in recv.mtype.collect_mclassdefs(self.mainmodule)
-		do
-			var n = self.modelbuilder.mclassdef2nclassdef[cd]
-			for npropdef in n.n_propdefs do
-				if npropdef isa AAttrPropdef and npropdef.n_expr == null then
-					# Force read to check the initialization
-					self.read_attribute(npropdef.mpropdef.mproperty, recv)
-				end
-			end
+		for npropdef in collect_attr_propdef(recv.mtype) do
+			npropdef.init_expr(self, recv)
 		end
 	end
 
@@ -407,34 +475,43 @@ private class NaiveInterpreter
 end
 
 # An instance represents a value of the executed program.
-class Instance
+abstract class Instance
 	# The dynamic type of the instance
 	# ASSERT: not self.mtype.is_anchored
 	var mtype: MType
 
-	# The values of the attributes
-	var attributes: Map[MAttribute, Instance] = new HashMap[MAttribute, Instance]
-
 	# return true if the instance is the true value.
 	# return false if the instance is the true value.
 	# else aborts
 	fun is_true: Bool do abort
 
-	# Return true if `self' IS `o' (using the Nit semantic of is)
-	fun eq_is(o: Instance): Bool do return self is o
+	# 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)
 
 	# Human readable object identity "Type#number"
-	redef fun to_s do return "{mtype}#{object_id}"
+	redef fun to_s do return "{mtype}"
 
-	# Return the integer valur is the instance is an integer.
+	# Return the integer value if the instance is an integer.
 	# else aborts
 	fun to_i: Int do abort
 
+	# Return the integer value if the instance is a float.
+	# else aborts
+	fun to_f: Float do abort
+
 	# The real value encapsulated if the instance is primitive.
 	# Else aborts.
 	fun val: Object do abort
 end
 
+# A instance with attribute (standards objects)
+class MutableInstance
+	super Instance
+
+	# The values of the attributes
+	var attributes: Map[MAttribute, Instance] = new HashMap[MAttribute, Instance]
+end
+
 # Special instance to handle primitives values (int, bool, etc.)
 # The trick it just to encapsulate the <<real>> value
 class PrimitiveInstance[E: Object]
@@ -465,27 +542,14 @@ class PrimitiveInstance[E: Object]
 	redef fun eq_is(o)
 	do
 		if not o isa PrimitiveInstance[Object] then return false
-		return self.val is o.val
+		return self.val.is_same_instance(o.val)
 	end
 
 	redef fun to_s do return "{mtype}#{val.object_id}({val})"
 
 	redef fun to_i do return val.as(Int)
-end
-
-private class ClosureInstance
-	super Instance
-
-	var frame: Frame
-
-	var nclosuredef: AClosureDef
 
-	init(mtype: MType, frame: Frame, nclosuredef: AClosureDef)
-	do
-		super(mtype)
-		self.frame = frame
-		self.nclosuredef = nclosuredef
-	end
+	redef fun to_f do return val.as(Float)
 end
 
 # Information about local variables in a running method
@@ -504,21 +568,22 @@ end
 
 redef class ANode
 	# Aborts the program with a message
-	# `v' is used to know if a colored message is displayed or not
+	# `v` is used to know if a colored message is displayed or not
 	private fun fatal(v: NaiveInterpreter, message: String)
 	do
 		if v.modelbuilder.toolcontext.opt_no_color.value == true then
-			print("Runtime error: {message} ({location.file.filename}:{location.line_start})")
+			stderr.write("Runtime error: {message} ({location.file.filename}:{location.line_start})\n")
 		else
-			print("{location}: Runtime error: {message}\n{location.colored_line("0;31")}")
-			print(v.stack_trace)
+			stderr.write("{location}: Runtime error: {message}\n{location.colored_line("0;31")}\n")
+			stderr.write(v.stack_trace)
+			stderr.write("\n")
 		end
 		exit(1)
 	end
 end
 
 redef class APropdef
-	# Execute a `mpropdef' associated with the current node.
+	# Execute a `mpropdef` associated with the current node.
 	private fun call(v: NaiveInterpreter, mpropdef: MMethodDef, args: Array[Instance]): nullable Instance
 	do
 		fatal(v, "NOT YET IMPLEMENTED method kind {class_name}. {mpropdef}")
@@ -526,51 +591,60 @@ redef class APropdef
 	end
 end
 
-redef class AConcreteMethPropdef
+redef class AMethPropdef
+	super TablesCapable
+
 	redef fun call(v, mpropdef, args)
 	do
 		var f = new Frame(self, self.mpropdef.as(not null), args)
+		var res = call_commons(v, mpropdef, args, f)
+		v.frames.shift
+		if v.returnmark == f then
+			v.returnmark = null
+			res = v.escapevalue
+			v.escapevalue = null
+			return res
+		end
+		return res
+	end
+
+	private fun call_commons(v: NaiveInterpreter, mpropdef: MMethodDef, arguments: Array[Instance], f: Frame): nullable Instance
+	do
 		for i in [0..mpropdef.msignature.arity[ do
 			var variable = self.n_signature.n_params[i].variable
 			assert variable != null
-			f.map[variable] = args[i+1]
-		end
-		for i in [0..mpropdef.msignature.mclosures.length[ do
-			var c = mpropdef.msignature.mclosures[i]
-			var variable = self.n_signature.n_closure_decls[i].variable
-			assert variable != null
-			f.map[variable] = args[i + 1 + mpropdef.msignature.arity]
+			f.map[variable] = arguments[i+1]
 		end
 
 		v.frames.unshift(f)
 
+		if mpropdef.is_abstract then
+			v.fatal("Abstract method `{mpropdef.mproperty.name}` called on `{arguments.first.mtype}`")
+			abort
+		end
+
 		# Call the implicit super-init
 		var auto_super_inits = self.auto_super_inits
 		if auto_super_inits != null then
-			var selfarg = [args.first]
+			var args = [arguments.first]
 			for auto_super_init in auto_super_inits do
-				if auto_super_init.intro.msignature.arity == 0 then
-					v.send(auto_super_init, selfarg)
-				else
-					v.send(auto_super_init, args)
+				args.clear
+				for i in [0..auto_super_init.msignature.arity+1[ do
+					args.add(arguments[i])
 				end
+				v.callsite(auto_super_init, args)
 			end
 		end
 
-		v.stmt(self.n_block)
-		v.frames.shift
-		if v.returnmark == f then
-			v.returnmark = null
-			var res = v.escapevalue
-			v.escapevalue = null
-			return res
+		if n_block != null then
+			v.stmt(self.n_block)
+			return null
+		else
+			return intern_call(v, mpropdef, arguments)
 		end
-		return null
 	end
-end
 
-redef class AInternMethPropdef
-	redef fun call(v, mpropdef, args)
+	private fun intern_call(v: NaiveInterpreter, mpropdef: MMethodDef, args: Array[Instance]): nullable Instance
 	do
 		var pname = mpropdef.mproperty.name
 		var cname = mpropdef.mclassdef.mclass.name
@@ -587,11 +661,11 @@ redef class AInternMethPropdef
 			end
 		else if pname == "output_class_name" then
 			var recv = args.first
-			print recv.mtype.as(MClassType).mclass
+			print recv.mtype
 			return null
 		else if pname == "native_class_name" then
 			var recv = args.first
-			var txt = recv.mtype.as(MClassType).mclass.to_s
+			var txt = recv.mtype.to_s
 			return v.native_string_instance(txt)
 		else if pname == "==" then
 			# == is correclt redefined for instances
@@ -600,18 +674,17 @@ redef class AInternMethPropdef
 			return v.bool_instance(args[0] != args[1])
 		else if pname == "is_same_type" then
 			return v.bool_instance(args[0].mtype == args[1].mtype)
+		else if pname == "is_same_instance" then
+			return v.bool_instance(args[1] != null and args[0].eq_is(args[1]))
 		else if pname == "exit" then
 			exit(args[1].to_i)
 			abort
 		else if pname == "sys" then
 			return v.mainobj
 		else if cname == "Int" then
+			var recvval = args[0].to_i
 			if pname == "unary -" then
 				return v.int_instance(-args[0].to_i)
-			else if pname == "succ" then
-				return v.int_instance(args[0].to_i + 1)
-			else if pname == "prec" then
-				return v.int_instance(args[0].to_i - 1)
 			else if pname == "+" then
 				return v.int_instance(args[0].to_i + args[1].to_i)
 			else if pname == "-" then
@@ -640,15 +713,22 @@ redef class AInternMethPropdef
 				return v.int_instance(args[0].to_i.lshift(args[1].to_i))
 			else if pname == "rshift" then
 				return v.int_instance(args[0].to_i.rshift(args[1].to_i))
+			else if pname == "rand" then
+				var res = recvval.rand
+				return v.int_instance(res)
+			else if pname == "native_int_to_s" then
+				return v.native_string_instance(recvval.to_s)
+			else if pname == "strerror_ext" then
+				return v.native_string_instance(recvval.strerror)
 			end
 		else if cname == "Char" then
 			var recv = args[0].val.as(Char)
 			if pname == "ascii" then
 				return v.int_instance(recv.ascii)
-			else if pname == "succ" then
-				return v.char_instance(recv.succ)
-			else if pname == "prec" then
-				return v.char_instance(recv.prec)
+			else if pname == "successor" then
+				return v.char_instance(recv.successor(args[1].to_i))
+			else if pname == "predecessor" then
+				return v.char_instance(recv.predecessor(args[1].to_i))
 			else if pname == "<" then
 				return v.bool_instance(recv < args[1].val.as(Char))
 			else if pname == ">" then
@@ -661,16 +741,57 @@ redef class AInternMethPropdef
 				return v.int_instance(recv <=> args[1].val.as(Char))
 			end
 		else if cname == "Float" then
-			if pname == "+" then
-				return v.float_instance(args[0].val.as(Float) + args[1].val.as(Float))
+			var recv = args[0].to_f
+			if pname == "unary -" then
+				return v.float_instance(-recv)
+			else if pname == "+" then
+				return v.float_instance(recv + args[1].to_f)
 			else if pname == "-" then
-				return v.float_instance(args[0].val.as(Float) - args[1].val.as(Float))
+				return v.float_instance(recv - args[1].to_f)
 			else if pname == "*" then
-				return v.float_instance(args[0].val.as(Float) * args[1].val.as(Float))
+				return v.float_instance(recv * args[1].to_f)
 			else if pname == "/" then
-				return v.float_instance(args[0].val.as(Float) / args[1].val.as(Float))
+				return v.float_instance(recv / args[1].to_f)
+			else if pname == "<" then
+				return v.bool_instance(recv < args[1].to_f)
+			else if pname == ">" then
+				return v.bool_instance(recv > args[1].to_f)
+			else if pname == "<=" then
+				return v.bool_instance(recv <= args[1].to_f)
+			else if pname == ">=" then
+				return v.bool_instance(recv >= args[1].to_f)
 			else if pname == "to_i" then
-				return v.int_instance(args[0].val.as(Float).to_i)
+				return v.int_instance(recv.to_i)
+			else if pname == "cos" then
+				return v.float_instance(args[0].to_f.cos)
+			else if pname == "sin" then
+				return v.float_instance(args[0].to_f.sin)
+			else if pname == "tan" then
+				return v.float_instance(args[0].to_f.tan)
+			else if pname == "acos" then
+				return v.float_instance(args[0].to_f.acos)
+			else if pname == "asin" then
+				return v.float_instance(args[0].to_f.asin)
+			else if pname == "atan" then
+				return v.float_instance(args[0].to_f.atan)
+			else if pname == "sqrt" then
+				return v.float_instance(args[0].to_f.sqrt)
+			else if pname == "exp" then
+				return v.float_instance(args[0].to_f.exp)
+			else if pname == "log" then
+				return v.float_instance(args[0].to_f.log)
+			else if pname == "pow" then
+				return v.float_instance(args[0].to_f.pow(args[1].to_f))
+			else if pname == "rand" then
+				return v.float_instance(args[0].to_f.rand)
+			else if pname == "abs" then
+				return v.float_instance(args[0].to_f.abs)
+			else if pname == "hypot_with" then
+				return v.float_instance(args[0].to_f.hypot_with(args[1].to_f))
+			else if pname == "is_nan" then
+				return v.bool_instance(args[0].to_f.is_nan)
+			else if pname == "is_inf_extern" then
+				return v.bool_instance(args[0].to_f.is_inf != 0)
 			end
 		else if cname == "NativeString" then
 			var recvval = args.first.val.as(Buffer)
@@ -679,17 +800,17 @@ redef class AInternMethPropdef
 				if arg1 >= recvval.length or arg1 < 0 then
 					debug("Illegal access on {recvval} for element {arg1}/{recvval.length}")
 				end
-				return v.char_instance(recvval[arg1])
+				return v.char_instance(recvval.chars[arg1])
 			else if pname == "[]=" then
 				var arg1 = args[1].to_i
 				if arg1 >= recvval.length or arg1 < 0 then
 					debug("Illegal access on {recvval} for element {arg1}/{recvval.length}")
 				end
-				recvval[arg1] = args[2].val.as(Char)
+				recvval.chars[arg1] = args[2].val.as(Char)
 				return null
 			else if pname == "copy_to" then
 				# sig= copy_to(dest: NativeString, length: Int, from: Int, to: Int)
-				var destval = args[1].val.as(Buffer)
+				var destval = args[1].val.as(FlatBuffer)
 				var lenval = args[2].to_i
 				var fromval = args[3].to_i
 				var toval = args[4].to_i
@@ -705,10 +826,28 @@ redef class AInternMethPropdef
 				if toval + lenval >= destval.length then
 					debug("Illegal access on {destval} for element {toval}+{lenval}/{destval.length}")
 				end
-				recvval.copy(fromval, lenval, destval, toval)
+				recvval.as(FlatBuffer).copy(fromval, lenval, destval, toval)
 				return null
 			else if pname == "atoi" then
 				return v.int_instance(recvval.to_i)
+			else if pname == "file_exists" then
+				return v.bool_instance(recvval.to_s.file_exists)
+			else if pname == "file_mkdir" then
+				recvval.to_s.mkdir
+				return null
+			else if pname == "file_chdir" then
+				recvval.to_s.chdir
+				return null
+			else if pname == "file_realpath" then
+				return v.native_string_instance(recvval.to_s.realpath)
+			else if pname == "get_environ" then
+				var txt = recvval.to_s.environ
+				return v.native_string_instance(txt)
+			else if pname == "system" then
+				var res = sys.system(recvval.to_s)
+				return v.int_instance(res)
+			else if pname == "atof" then
+				return v.float_instance(recvval.to_f)
 			end
 		else if pname == "calloc_string" then
 			return v.native_string_instance("!" * args[1].to_i)
@@ -722,93 +861,54 @@ redef class AInternMethPropdef
 			else if pname == "[]=" then
 				recvval[args[1].to_i] = args[2]
 				return null
+			else if pname == "length" then
+				return v.int_instance(recvval.length)
 			else if pname == "copy_to" then
 				recvval.copy(0, args[2].to_i, args[1].val.as(Array[Instance]), 0)
 				return null
 			end
-		else if pname == "calloc_array" then
-			var recvtype = args.first.mtype.as(MClassType)
-			var mtype: MType = recvtype.supertype_to(v.mainmodule, recvtype, v.mainmodule.get_primitive_class("ArrayCapable"))
-			mtype = mtype.as(MGenericType).arguments.first
-			var val = new Array[Instance].filled_with(v.null_instance, args[1].to_i)
-			return new PrimitiveInstance[Array[Instance]](v.mainmodule.get_primitive_class("NativeArray").get_mtype([mtype]), val)
-		end
-		fatal(v, "NOT YET IMPLEMENTED intern {mpropdef}")
-		abort
-	end
-end
-
-redef class AbstractArray[E]
-	fun copy(start: Int, len: Int, dest: AbstractArray[E], new_start: Int)
-	do
-		self.copy_to(start, len, dest, new_start)
-	end
-end
-
-redef class AExternInitPropdef
-	redef fun call(v, mpropdef, args)
-	do
-		var pname = mpropdef.mproperty.name
-		var cname = mpropdef.mclassdef.mclass.name
-		if pname == "native_stdout" then
-			return new PrimitiveInstance[OStream](mpropdef.mclassdef.mclass.mclass_type, stdout)
-		else if pname == "native_stdin" then
-			return new PrimitiveInstance[IStream](mpropdef.mclassdef.mclass.mclass_type, stdin)
-		else if pname == "native_stderr" then
-			return new PrimitiveInstance[OStream](mpropdef.mclassdef.mclass.mclass_type, stderr)
-		else if pname == "io_open_read" then
-			var a1 = args[1].val.as(Buffer)
-			return new PrimitiveInstance[IStream](mpropdef.mclassdef.mclass.mclass_type, new IFStream.open(a1.to_s))
-		else if pname == "io_open_write" then
-			var a1 = args[1].val.as(Buffer)
-			return new PrimitiveInstance[OStream](mpropdef.mclassdef.mclass.mclass_type, new OFStream.open(a1.to_s))
-		end
-		fatal(v, "NOT YET IMPLEMENTED extern init {mpropdef}")
-		abort
-	end
-end
-
-redef class AExternMethPropdef
-	super TablesCapable
-	redef fun call(v, mpropdef, args)
-	do
-		var pname = mpropdef.mproperty.name
-		var cname = mpropdef.mclassdef.mclass.name
-		if cname == "Int" then
-			var recvval = args.first.val.as(Int)
-			if pname == "rand" then
-				var res = recvval.rand
-				return v.int_instance(res)
-			end
 		else if cname == "NativeFile" then
+			if pname == "native_stdout" then
+				return new PrimitiveInstance[OStream](mpropdef.mclassdef.mclass.mclass_type, stdout)
+			else if pname == "native_stdin" then
+				return new PrimitiveInstance[IStream](mpropdef.mclassdef.mclass.mclass_type, stdin)
+			else if pname == "native_stderr" then
+				return new PrimitiveInstance[OStream](mpropdef.mclassdef.mclass.mclass_type, stderr)
+			else if pname == "io_open_read" then
+				var a1 = args[1].val.as(Buffer)
+				return new PrimitiveInstance[IStream](mpropdef.mclassdef.mclass.mclass_type, new IFStream.open(a1.to_s))
+			else if pname == "io_open_write" then
+				var a1 = args[1].val.as(Buffer)
+				return new PrimitiveInstance[OStream](mpropdef.mclassdef.mclass.mclass_type, new OFStream.open(a1.to_s))
+			end
 			var recvval = args.first.val
 			if pname == "io_write" then
 				var a1 = args[1].val.as(Buffer)
-				recvval.as(OStream).write(a1.substring(0, args[2].to_i))
+				recvval.as(OStream).write(a1.substring(0, args[2].to_i).to_s)
 				return args[2]
 			else if pname == "io_read" then
 				var str = recvval.as(IStream).read(args[2].to_i)
 				var a1 = args[1].val.as(Buffer)
-				new Buffer.from(str).copy(0, str.length, a1, 0)
+				new FlatBuffer.from(str).copy(0, str.length, a1.as(FlatBuffer), 0)
 				return v.int_instance(str.length)
 			else if pname == "io_close" then
 				recvval.as(IOS).close
 				return v.int_instance(0)
+			else if pname == "address_is_null" then
+				return v.false_instance
 			end
-		else if cname == "NativeString" then
-			var recvval = args.first.val.as(Buffer)
-			if pname == "file_exists" then
-				return v.bool_instance(recvval.to_s.file_exists)
-			else if pname == "file_mkdir" then
-				recvval.to_s.mkdir
-				return null
-			else if pname == "get_environ" then
-				var txt = recvval.to_s.environ
-				return v.native_string_instance(txt)
-			else if pname == "system" then
-				var res = sys.system(recvval.to_s)
-				return v.int_instance(res)
-			end
+		else if pname == "calloc_array" then
+			var recvtype = args.first.mtype.as(MClassType)
+			var mtype: MType
+			mtype = recvtype.supertype_to(v.mainmodule, recvtype, v.mainmodule.get_primitive_class("ArrayCapable"))
+			mtype = mtype.arguments.first
+			var val = new Array[Instance].filled_with(v.null_instance, args[1].to_i)
+			return new PrimitiveInstance[Array[Instance]](v.mainmodule.get_primitive_class("NativeArray").get_mtype([mtype]), val)
+		else if pname == "native_argc" then
+			return v.int_instance(v.arguments.length)
+		else if pname == "native_argv" then
+			var txt = v.arguments[args[1].to_i]
+			return v.native_string_instance(txt)
 		else if pname == "native_argc" then
 			return v.int_instance(v.arguments.length)
 		else if pname == "native_argv" then
@@ -816,6 +916,13 @@ redef class AExternMethPropdef
 			return v.native_string_instance(txt)
 		else if pname == "get_time" then
 			return v.int_instance(get_time)
+		else if pname == "srand_from" then
+			srand_from(args[1].to_i)
+			return null
+		else if pname == "atan2" then
+			return v.float_instance(atan2(args[1].to_f, args[2].to_f))
+		else if pname == "pi" then
+			return v.float_instance(pi)
 		else if pname == "lexer_goto" then
 			return v.int_instance(lexer_goto(args[1].to_i, args[2].to_i))
 		else if pname == "lexer_accept" then
@@ -824,28 +931,50 @@ redef class AExternMethPropdef
 			return v.int_instance(parser_goto(args[1].to_i, args[2].to_i))
 		else if pname == "parser_action" then
 			return v.int_instance(parser_action(args[1].to_i, args[2].to_i))
+		else if pname == "file_getcwd" then
+			return v.native_string_instance(getcwd)
+		else if pname == "errno" then
+			return v.int_instance(sys.errno)
+		else if pname == "address_is_null" then
+			return v.false_instance
+		end
+		if mpropdef.is_intern then
+			fatal(v, "NOT YET IMPLEMENTED intern {mpropdef}")
+		else if mpropdef.is_extern then
+			fatal(v, "NOT YET IMPLEMENTED extern {mpropdef}")
+		else
+			fatal(v, "NOT YET IMPLEMENTED <wat?> {mpropdef}")
 		end
-		fatal(v, "NOT YET IMPLEMENTED extern {mpropdef}")
 		abort
 	end
 end
 
+redef class AbstractArray[E]
+	fun copy(start: Int, len: Int, dest: AbstractArray[E], new_start: Int)
+	do
+		self.copy_to(start, len, dest, new_start)
+	end
+end
+
 redef class AAttrPropdef
 	redef fun call(v, mpropdef, args)
 	do
+		var recv = args.first
+		assert recv isa MutableInstance
 		var attr = self.mpropdef.mproperty
 		if args.length == 1 then
-			return v.read_attribute(attr, args.first)
+			return v.read_attribute(attr, recv)
 		else
 			assert args.length == 2
-			args.first.attributes[attr] = args[1]
+			recv.attributes[attr] = args[1]
 			return null
 		end
 	end
 
-	# Evaluate and set the default value of the attribute in `recv'
+	# Evaluate and set the default value of the attribute in `recv`
 	private fun init_expr(v: NaiveInterpreter, recv: Instance)
 	do
+		assert recv isa MutableInstance
 		var nexpr = self.n_expr
 		if nexpr != null then
 			var f = new Frame(self, self.mpropdef.as(not null), [recv])
@@ -858,8 +987,7 @@ redef class AAttrPropdef
 			return
 		end
 		var mtype = self.mpropdef.static_mtype.as(not null)
-		# TODO The needinit info is statically computed, move it to modelbuilder or whatever
-		mtype = mtype.resolve_for(self.mpropdef.mclassdef.bound_mtype, self.mpropdef.mclassdef.bound_mtype, self.mpropdef.mclassdef.mmodule, true)
+		mtype = mtype.anchor_to(v.mainmodule, recv.mtype.as(MClassType))
 		if mtype isa MNullableType then
 			recv.attributes[self.mpropdef.mproperty] = v.null_instance
 		end
@@ -867,7 +995,7 @@ redef class AAttrPropdef
 end
 
 redef class AClassdef
-	# Execute an implicit `mpropdef' associated with the current node.
+	# Execute an implicit `mpropdef` associated with the current node.
 	private fun call(v: NaiveInterpreter, mpropdef: MMethodDef, args: Array[Instance]): nullable Instance
 	do
 		var super_inits = self.super_inits
@@ -879,6 +1007,7 @@ redef class AClassdef
 			return null
 		end
 		var recv = args.first
+		assert recv isa MutableInstance
 		var i = 1
 		# Collect undefined attributes
 		for npropdef in self.n_propdefs do
@@ -894,7 +1023,7 @@ end
 redef class AExpr
 	# Evaluate the node as a possible expression.
 	# Return a possible value
-	# NOTE: Do not call this method directly, but use `v.expr'
+	# NOTE: Do not call this method directly, but use `v.expr`
 	# This method is here to be implemented by subclasses.
 	private fun expr(v: NaiveInterpreter): nullable Instance
 	do
@@ -903,7 +1032,7 @@ redef class AExpr
 	end
 
 	# Evaluate the node as a statement.
-	# NOTE: Do not call this method directly, but use `v.stmt'
+	# NOTE: Do not call this method directly, but use `v.stmt`
 	# This method is here to be implemented by subclasses (no need to return something).
 	private fun stmt(v: NaiveInterpreter)
 	do
@@ -913,6 +1042,17 @@ redef class AExpr
 end
 
 redef class ABlockExpr
+	redef fun expr(v)
+	do
+		var last = self.n_expr.last
+		for e in self.n_expr do
+			if e == last then break
+			v.stmt(e)
+			if v.is_escaping then return null
+		end
+		return last.expr(v)
+	end
+
 	redef fun stmt(v)
 	do
 		for e in self.n_expr do
@@ -942,11 +1082,12 @@ redef class AVarExpr
 end
 
 redef class AVarAssignExpr
-	redef fun stmt(v)
+	redef fun expr(v)
 	do
 		var i = v.expr(self.n_value)
-		if i == null then return
+		if i == null then return null
 		v.frame.map[self.variable.as(not null)] = i
+		return i
 	end
 end
 
@@ -956,7 +1097,7 @@ redef class AVarReassignExpr
 		var vari = v.frame.map[self.variable.as(not null)]
 		var value = v.expr(self.n_value)
 		if value == null then return
-		var res = v.send(reassign_property.mproperty, [vari, value])
+		var res = v.callsite(reassign_callsite, [vari, value])
 		assert res != null
 		v.frame.map[self.variable.as(not null)] = res
 	end
@@ -1017,6 +1158,17 @@ redef class AAbortExpr
 end
 
 redef class AIfExpr
+	redef fun expr(v)
+	do
+		var cond = v.expr(self.n_expr)
+		if cond == null then return null
+		if cond.is_true then
+			return v.expr(self.n_then.as(not null))
+		else
+			return v.expr(self.n_else.as(not null))
+		end
+	end
+
 	redef fun stmt(v)
 	do
 		var cond = v.expr(self.n_expr)
@@ -1082,20 +1234,22 @@ redef class AForExpr
 	do
 		var col = v.expr(self.n_expr)
 		if col == null then return
+		if col.mtype isa MNullType then fatal(v, "Receiver is null")
+
 		#self.debug("col {col}")
-		var iter = v.send(v.mainmodule.force_get_primitive_method("iterator", col.mtype), [col]).as(not null)
+		var iter = v.callsite(method_iterator, [col]).as(not null)
 		#self.debug("iter {iter}")
 		loop
-			var isok = v.send(v.mainmodule.force_get_primitive_method("is_ok", iter.mtype), [iter]).as(not null)
+			var isok = v.callsite(method_is_ok, [iter]).as(not null)
 			if not isok.is_true then return
 			if self.variables.length == 1 then
-				var item = v.send(v.mainmodule.force_get_primitive_method("item", iter.mtype), [iter]).as(not null)
+				var item = v.callsite(method_item, [iter]).as(not null)
 				#self.debug("item {item}")
 				v.frame.map[self.variables.first] = item
 			else if self.variables.length == 2 then
-				var key = v.send(v.mainmodule.force_get_primitive_method("key", iter.mtype), [iter]).as(not null)
+				var key = v.callsite(method_key, [iter]).as(not null)
 				v.frame.map[self.variables[0]] = key
-				var item = v.send(v.mainmodule.force_get_primitive_method("item", iter.mtype), [iter]).as(not null)
+				var item = v.callsite(method_item, [iter]).as(not null)
 				v.frame.map[self.variables[1]] = item
 			else
 				abort
@@ -1104,7 +1258,7 @@ redef class AForExpr
 			if v.is_break(self.escapemark) then return
 			v.is_continue(self.escapemark) # Clear the break
 			if v.is_escaping then return
-			v.send(v.mainmodule.force_get_primitive_method("next", iter.mtype), [iter])
+			v.callsite(method_next, [iter])
 		end
 	end
 end
@@ -1138,6 +1292,16 @@ redef class AOrExpr
 	end
 end
 
+redef class AImpliesExpr
+	redef fun expr(v)
+	do
+		var cond = v.expr(self.n_expr)
+		if cond == null then return null
+		if not cond.is_true then return v.true_instance
+		return v.expr(self.n_expr2)
+	end
+end
+
 redef class AAndExpr
 	redef fun expr(v)
 	do
@@ -1167,17 +1331,6 @@ redef class AOrElseExpr
 	end
 end
 
-redef class AEeExpr
-	redef fun expr(v)
-	do
-		var i = v.expr(self.n_expr)
-		if i == null then return null
-		var i2 = v.expr(self.n_expr2)
-		if i2 == null then return null
-		return v.bool_instance(i.eq_is(i2))
-	end
-end
-
 redef class AIntExpr
 	redef fun expr(v)
 	do
@@ -1208,7 +1361,7 @@ redef class AArrayExpr
 			if i == null then return null
 			val.add(i)
 		end
-		var mtype = v.unanchor_type(self.mtype.as(not null)).as(MGenericType)
+		var mtype = v.unanchor_type(self.mtype.as(not null)).as(MClassType)
 		var elttype = mtype.arguments.first
 		return v.array_instance(val, elttype)
 	end
@@ -1219,10 +1372,7 @@ redef class AStringFormExpr
 	do
 		var txt = self.value.as(not null)
 		var nat = v.native_string_instance(txt)
-		var res = new Instance(v.mainmodule.get_primitive_class("String").mclass_type)
-		v.init_instance(res)
-		v.send(v.mainmodule.force_get_primitive_method("from_cstring", res.mtype), [res, nat])
-		v.check_init_instance(res)
+		var res = v.send(v.force_get_primitive_method("to_s", nat.mtype), [nat]).as(not null)
 		return res
 	end
 end
@@ -1237,7 +1387,7 @@ redef class ASuperstringExpr
 			array.add(i)
 		end
 		var i = v.array_instance(array, v.mainmodule.get_primitive_class("Object").mclass_type)
-		var res = v.send(v.mainmodule.force_get_primitive_method("to_s", i.mtype), [i])
+		var res = v.send(v.force_get_primitive_method("to_s", i.mtype), [i])
 		assert res != null
 		return res
 	end
@@ -1251,10 +1401,9 @@ redef class ACrangeExpr
 		var e2 = v.expr(self.n_expr2)
 		if e2 == null then return null
 		var mtype = v.unanchor_type(self.mtype.as(not null))
-		var res = new Instance(mtype)
+		var res = new MutableInstance(mtype)
 		v.init_instance(res)
-		v.send(v.mainmodule.force_get_primitive_method("init", mtype), [res, e1, e2])
-		v.check_init_instance(res)
+		v.callsite(init_callsite, [res, e1, e2])
 		return res
 	end
 end
@@ -1267,10 +1416,9 @@ redef class AOrangeExpr
 		var e2 = v.expr(self.n_expr2)
 		if e2 == null then return null
 		var mtype = v.unanchor_type(self.mtype.as(not null))
-		var res = new Instance(mtype)
+		var res = new MutableInstance(mtype)
 		v.init_instance(res)
-		v.send(v.mainmodule.force_get_primitive_method("without_last", mtype), [res, e1, e2])
-		v.check_init_instance(res)
+		v.callsite(init_callsite, [res, e1, e2])
 		return res
 	end
 end
@@ -1311,10 +1459,10 @@ redef class AAsCastExpr
 	do
 		var i = v.expr(self.n_expr)
 		if i == null then return null
-		var mtype = v.unanchor_type(self.mtype.as(not null))
-		if not v.is_subtype(i.mtype, mtype) then
-			#fatal(v, "Cast failed expected {mtype}, got {i}")
-			fatal(v, "Cast failed")
+		var mtype = self.mtype.as(not null)
+		var amtype = v.unanchor_type(mtype)
+		if not v.is_subtype(i.mtype, amtype) then
+			fatal(v, "Cast failed. Expected `{amtype}`, got `{i.mtype}`")
 		end
 		return i
 	end
@@ -1365,18 +1513,8 @@ redef class ASendExpr
 			if i == null then return null
 			args.add(i)
 		end
-		for c in self.n_closure_defs do
-			var mtype = c.mclosure.mtype
-			var instance = new ClosureInstance(mtype, v.frame, c)
-			args.add(instance)
-		end
-		var mproperty = self.mproperty.as(not null)
 
-		var res = v.send(mproperty, args)
-		if v.is_break(self.escapemark) then
-			res = v.escapevalue
-			v.escapevalue = null
-		end
+		var res = v.callsite(callsite, args)
 		return res
 	end
 end
@@ -1395,16 +1533,15 @@ redef class ASendReassignFormExpr
 		var value = v.expr(self.n_value)
 		if value == null then return
 
-		var mproperty = self.mproperty.as(not null)
-		var read = v.send(mproperty, args)
+		var read = v.callsite(callsite, args)
 		assert read != null
 
-		var write = v.send(self.reassign_property.mproperty, [read, value])
+		var write = v.callsite(reassign_callsite, [read, value])
 		assert write != null
 
 		args.add(write)
 
-		v.send(self.write_mproperty.as(not null), args)
+		v.callsite(write_callsite, args)
 	end
 end
 
@@ -1418,30 +1555,28 @@ redef class ASuperExpr
 			if i == null then return null
 			args.add(i)
 		end
-		if args.length == 1 then
-			args = v.frame.arguments
-		end
 
-		var mproperty = self.mproperty
-		if mproperty != null then
-			if mproperty.intro.msignature.arity == 0 then
-				args = [recv]
+		var callsite = self.callsite
+		if callsite != null then
+			# Add additionnals arguments for the super init call
+			if args.length == 1 then
+				for i in [0..callsite.mproperty.intro.msignature.arity[ do
+					args.add(v.frame.arguments[i+1])
+				end
 			end
 			# Super init call
-			var res = v.send(mproperty, args)
+			var res = v.callsite(callsite, args)
 			return res
 		end
 
-		# stantard call-next-method
-		var mpropdef = v.frame.mpropdef
-		# FIXME: we do not want an ugly static call!
-		var mpropdefs = mpropdef.mproperty.lookup_super_definitions(mpropdef.mclassdef.mmodule, mpropdef.mclassdef.bound_mtype)
-		if mpropdefs.length != 1 then
-			debug("Warning: NOT YET IMPLEMENTED: multiple MPRODFEFS for super {mpropdef} for {recv}: {mpropdefs.join(", ")}")
+		if args.length == 1 then
+			args = v.frame.arguments
 		end
-		mpropdef = mpropdefs.first
-		assert mpropdef isa MMethodDef
-		var res = v.call(mpropdef, args)
+
+		# stantard call-next-method
+		var mpropdef = self.mpropdef
+		mpropdef = mpropdef.lookup_next_definition(v.mainmodule, recv.mtype)
+		var res = v.call_without_varargs(mpropdef, args)
 		return res
 	end
 end
@@ -1450,7 +1585,7 @@ redef class ANewExpr
 	redef fun expr(v)
 	do
 		var mtype = v.unanchor_type(self.mtype.as(not null))
-		var recv = new Instance(mtype)
+		var recv: Instance = new MutableInstance(mtype)
 		v.init_instance(recv)
 		var args = [recv]
 		for a in self.n_args.n_exprs do
@@ -1458,13 +1593,11 @@ redef class ANewExpr
 			if i == null then return null
 			args.add(i)
 		end
-		var mproperty = self.mproperty.as(not null)
-		var res2 = v.send(mproperty, args)
+		var res2 = v.callsite(callsite, args)
 		if res2 != null then
 			#self.debug("got {res2} from {mproperty}. drop {recv}")
 			return res2
 		end
-		v.check_init_instance(recv)
 		return recv
 	end
 end
@@ -1474,6 +1607,7 @@ 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")
 		var mproperty = self.mproperty.as(not null)
 		return v.read_attribute(mproperty, recv)
 	end
@@ -1484,9 +1618,11 @@ 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")
 		var i = v.expr(self.n_value)
 		if i == null then return
 		var mproperty = self.mproperty.as(not null)
+		assert recv isa MutableInstance
 		recv.attributes[mproperty] = i
 	end
 end
@@ -1496,12 +1632,14 @@ 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")
 		var value = v.expr(self.n_value)
 		if value == null then return
 		var mproperty = self.mproperty.as(not null)
 		var attr = v.read_attribute(mproperty, recv)
-		var res = v.send(reassign_property.mproperty, [attr, value])
+		var res = v.callsite(reassign_callsite, [attr, value])
 		assert res != null
+		assert recv isa MutableInstance
 		recv.attributes[mproperty] = res
 	end
 end
@@ -1511,27 +1649,13 @@ 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")
 		var mproperty = self.mproperty.as(not null)
+		assert recv isa MutableInstance
 		return v.bool_instance(recv.attributes.has_key(mproperty))
 	end
 end
 
-redef class AClosureCallExpr
-	redef fun expr(v)
-	do
-		var args = new Array[Instance]
-		for a in self.n_args.n_exprs do
-			var i = v.expr(a)
-			if i == null then return null
-			args.add(i)
-		end
-		var i = v.frame.map[self.variable.as(not null)]
-		assert i isa ClosureInstance
-		var res = v.call_closure(i, args)
-		return res
-	end
-end
-
 redef class ADebugTypeExpr
 	redef fun stmt(v)
 	do