diff --git a/vhdlpp/architec_emit.cc b/vhdlpp/architec_emit.cc
index 46695543e..0c72d3bd3 100644
--- a/vhdlpp/architec_emit.cc
+++ b/vhdlpp/architec_emit.cc
@@ -152,22 +152,9 @@ int CondSignalAssignment::emit(ostream&out, Entity*ent, Architecture*arc)
     int errors = 0;
 
     out << "// " << get_fileline() << endl;
-    out << "always @(";
-
+    out << "always begin" << endl;
     bool first = true;
-    for(list<const ExpName*>::const_iterator it = sens_list_.begin();
-            it != sens_list_.end(); ++it) {
-        if(first)
-            first = false;
-        else
-            out << ",";
 
-        errors += (*it)->emit(out, ent, arc);
-    }
-
-    out << ") begin" << endl;
-
-    first = true;
     for(list<ExpConditional::case_t*>::iterator it = options_.begin();
             it != options_.end(); ++it) {
         ExpConditional::case_t*cas = *it;
@@ -192,6 +179,21 @@ int CondSignalAssignment::emit(ostream&out, Entity*ent, Architecture*arc)
         out << ";" << endl;
     }
 
+    // Sensitivity list
+    first = true;
+    out << "@(";
+
+    for(list<const ExpName*>::const_iterator it = sens_list_.begin();
+            it != sens_list_.end(); ++it) {
+        if(first)
+            first = false;
+        else
+            out << ",";
+
+        errors += (*it)->emit(out, ent, arc);
+    }
+
+    out << ");" << endl;
     out << "end" << endl;
 
     return errors;
diff --git a/vhdlpp/debug.cc b/vhdlpp/debug.cc
index af4fd7a32..717687d68 100644
--- a/vhdlpp/debug.cc
+++ b/vhdlpp/debug.cc
@@ -436,29 +436,6 @@ void ExpRelation::dump(ostream&out, int indent) const
       dump_operands(out, indent+4);
 }
 
-void ExpString::dump(ostream&out, int indent) const
-{
-    out << setw(indent) << "" << "String \"" << value_;
-    out << "\"" << " at " << get_fileline() << endl;
-}
-
-void ExpUAbs::dump(ostream&out, int indent) const
-{
-      out << setw(indent) << "" << "abs() at " << get_fileline() << endl;
-      dump_operand1(out, indent+4);
-}
-
-void ExpUnary::dump_operand1(ostream&out, int indent) const
-{
-      operand1_->dump(out, indent);
-}
-
-void ExpUNot::dump(ostream&out, int indent) const
-{
-      out << setw(indent) << "" << "not() at " << get_fileline() << endl;
-      dump_operand1(out, indent+4);
-}
-
 void named_expr_t::dump(ostream&out, int indent) const
 {
     out << setw(indent) << "" << name_ << "=>";
diff --git a/vhdlpp/expression.cc b/vhdlpp/expression.cc
index 9efe60931..b9dff1b91 100644
--- a/vhdlpp/expression.cc
+++ b/vhdlpp/expression.cc
@@ -24,6 +24,7 @@
 # include  "subprogram.h"
 # include  "parse_types.h"
 # include  "scope.h"
+# include  "library.h"
 # include  <iostream>
 # include  <typeinfo>
 # include  <cstring>
@@ -569,6 +570,32 @@ const VType* ExpFunc::func_ret_type() const
     return def_ ? def_->peek_return_type() : NULL;
 }
 
+SubprogramHeader*ExpFunc::match_signature(Entity*ent, ScopeBase*scope) const
+{
+    SubprogramHeader*prog = NULL;
+    list<const VType*> arg_types;
+
+      // Create a list of argument types to find a matching subprogram
+    for(vector<Expression*>::const_iterator it = argv_.begin();
+            it != argv_.end(); ++it) {
+        arg_types.push_back((*it)->probe_type(ent, scope));
+    }
+
+    prog = scope->match_subprogram(name_, &arg_types);
+
+    if(!prog)
+        prog = library_match_subprogram(name_, &arg_types);
+
+    if(!prog) {
+        cerr << get_fileline() << ": sorry: could not find function ";
+        emit_subprogram_sig(cerr, name_, arg_types);
+        cerr << endl;
+        ivl_assert(*this, false);
+    }
+
+    return prog;
+}
+
 ExpInteger::ExpInteger(int64_t val)
 : value_(val)
 {
@@ -818,6 +845,15 @@ ExpUNot::~ExpUNot()
 {
 }
 
+ExpUMinus::ExpUMinus(Expression*op1)
+: ExpUnary(op1)
+{
+}
+
+ExpUMinus::~ExpUMinus()
+{
+}
+
 ExpCast::ExpCast(Expression*base, const VType*type) :
     base_(base), type_(type)
 {
diff --git a/vhdlpp/expression.h b/vhdlpp/expression.h
index 65e1934bd..d31955a89 100644
--- a/vhdlpp/expression.h
+++ b/vhdlpp/expression.h
@@ -620,12 +620,15 @@ class ExpFunc : public Expression {
       void write_to_stream(std::ostream&fd) const;
       int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
       void dump(ostream&out, int indent = 0) const;
-      void visit(ExprVisitor& func); // NOTE: does not handle expressions in subprogram
+      void visit(ExprVisitor& func); // NOTE: does not handle expressions in subprogram body
+
+      // Returns a subprogram header that matches the function call
+      SubprogramHeader*match_signature(Entity*ent, ScopeBase*scope) const;
 
     private:
       perm_string name_;
       std::vector<Expression*> argv_;
-      SubprogramHeader*def_;
+      mutable SubprogramHeader*def_;
 };
 
 class ExpInteger : public Expression {
@@ -948,6 +951,19 @@ class ExpUNot : public ExpUnary {
       void dump(ostream&out, int indent = 0) const;
 };
 
+class ExpUMinus : public ExpUnary {
+
+    public:
+      explicit ExpUMinus(Expression*op1);
+      ~ExpUMinus();
+
+      Expression*clone() const { return new ExpUMinus(peek_operand()->clone()); }
+
+      void write_to_stream(std::ostream&fd) const;
+      int emit(ostream&out, Entity*ent, ScopeBase*scope) const;
+      void dump(ostream&out, int indent = 0) const;
+};
+
 /*
  * Class that wraps other expressions to cast them to other types.
  */
diff --git a/vhdlpp/expression_debug.cc b/vhdlpp/expression_debug.cc
index feaaf9510..cf6a46902 100644
--- a/vhdlpp/expression_debug.cc
+++ b/vhdlpp/expression_debug.cc
@@ -119,6 +119,35 @@ void ExpShift::dump(ostream&out, int indent) const
       dump_operands(out, indent+4);
 }
 
+void ExpString::dump(ostream&out, int indent) const
+{
+    out << setw(indent) << "" << "String \"" << value_;
+    out << "\"" << " at " << get_fileline() << endl;
+}
+
+void ExpUAbs::dump(ostream&out, int indent) const
+{
+      out << setw(indent) << "" << "abs() at " << get_fileline() << endl;
+      dump_operand1(out, indent+4);
+}
+
+void ExpUnary::dump_operand1(ostream&out, int indent) const
+{
+      operand1_->dump(out, indent);
+}
+
+void ExpUNot::dump(ostream&out, int indent) const
+{
+      out << setw(indent) << "" << "not() at " << get_fileline() << endl;
+      dump_operand1(out, indent+4);
+}
+
+void ExpUMinus::dump(ostream&out, int indent) const
+{
+      out << setw(indent) << "" << "unary_minus() at " << get_fileline() << endl;
+      dump_operand1(out, indent+4);
+}
+
 void ExpTime::dump(ostream&out, int indent) const
 {
       out << setw(indent) << "" << "Time ";
diff --git a/vhdlpp/expression_elaborate.cc b/vhdlpp/expression_elaborate.cc
index 7888f162a..97405ca0b 100644
--- a/vhdlpp/expression_elaborate.cc
+++ b/vhdlpp/expression_elaborate.cc
@@ -26,7 +26,6 @@
 # include  "entity.h"
 # include  "vsignal.h"
 # include  "subprogram.h"
-# include  "library.h"
 # include  "std_types.h"
 # include  <iostream>
 # include  <typeinfo>
@@ -74,14 +73,13 @@ const VType*ExpName::elaborate_adjust_type_with_range_(Entity*ent, ScopeBase*sco
 		    // If the name is an array, then a part select is
 		    // also an array, but with different bounds.
 		  int64_t use_msb, use_lsb;
-		  bool flag;
+		  bool flag = true;
 
-		  flag = range->msb()->evaluate(ent, scope, use_msb);
-		  ivl_assert(*this, flag);
-		  flag = range->lsb()->evaluate(ent, scope, use_lsb);
-		  ivl_assert(*this, flag);
+		  flag &= range->msb()->evaluate(ent, scope, use_msb);
+		  flag &= range->lsb()->evaluate(ent, scope, use_lsb);
 
-		  type = new VTypeArray(array->element_type(), use_msb, use_lsb);
+                  if(flag)
+                    type = new VTypeArray(array->element_type(), use_msb, use_lsb);
 	    }
 	    else if(idx) {
 		    // If the name is an array or a vector, then an
@@ -419,7 +417,7 @@ const VType*ExpAggregate::fit_type(Entity*, ScopeBase*, const VTypeArray*host) c
       Expression*use_msb = prange->msb();
       Expression*use_lsb = prange->lsb();
 
-      ivl_assert(*this, host->dimensions() == 1);
+      ivl_assert(*this, host->dimensions().size() == 1);
       vector<VTypeArray::range_t> range (1);
 
       range[0] = VTypeArray::range_t(use_msb, use_lsb);
@@ -580,6 +578,7 @@ int ExpArithmetic::elaborate_expr(Entity*ent, ScopeBase*scope, const VType*ltype
 
 const VType* ExpArithmetic::resolve_operand_types_(const VType*t1, const VType*t2) const
 {
+    // Ranges
       while (const VTypeRange*tmp = dynamic_cast<const VTypeRange*> (t1))
 	    t1 = tmp->base_type();
       while (const VTypeRange*tmp = dynamic_cast<const VTypeRange*> (t2))
@@ -588,7 +587,58 @@ const VType* ExpArithmetic::resolve_operand_types_(const VType*t1, const VType*t
       if (t1->type_match(t2))
 	    return t1;
 
-      return 0;
+    // Signed & unsigned (resized to the widest argument)
+    const VTypeArray*t1_arr = dynamic_cast<const VTypeArray*>(t1);
+    const VTypeArray*t2_arr = dynamic_cast<const VTypeArray*>(t2);
+
+    if(t1_arr && t2_arr) {
+        const VTypeArray*t1_parent = t1_arr->get_parent_type();
+        const VTypeArray*t2_parent = t2_arr->get_parent_type();
+
+        if(t1_parent == t2_parent
+                && (t1_parent == &primitive_SIGNED || t1_parent == &primitive_UNSIGNED)) {
+            int t1_size = t1_arr->get_width(NULL);
+            int t2_size = t2_arr->get_width(NULL);
+
+            // Easy, the same sizes, so we do not need to resize
+            if(t1_size == t2_size && t1_size > 0)
+                return t1;  // == t2
+
+            VTypeArray*resolved = new VTypeArray(t1_parent->element_type(),
+                    std::max(t1_size, t2_size) - 1, 0, t1_parent->signed_vector());
+            resolved->set_parent_type(t1_parent);
+
+            return resolved;
+        }
+
+    } else if(t1_arr) {
+        if(const VTypePrimitive*prim = dynamic_cast<const VTypePrimitive*>(t2)) {
+            const VTypeArray*t1_parent = t1_arr->get_parent_type();
+            VTypePrimitive::type_t t2_type = prim->type();
+
+            if((t2_type == VTypePrimitive::NATURAL || t2_type == VTypePrimitive::INTEGER)
+                    && t1_parent == &primitive_SIGNED)
+                return t1;
+
+            if((t2_type == VTypePrimitive::NATURAL) && t1_parent == &primitive_UNSIGNED)
+                return t1;
+        }
+
+    } else if(t2_arr) {
+        if(const VTypePrimitive*prim = dynamic_cast<const VTypePrimitive*>(t1)) {
+            const VTypeArray*t2_parent = t2_arr->get_parent_type();
+            VTypePrimitive::type_t t1_type = prim->type();
+
+            if((t1_type == VTypePrimitive::NATURAL || t1_type == VTypePrimitive::INTEGER)
+                    && t2_parent == &primitive_SIGNED)
+                return t2;
+
+            if((t1_type == VTypePrimitive::NATURAL) && t2_parent == &primitive_UNSIGNED)
+                return t2;
+        }
+    }
+
+    return 0;
 }
 
 int ExpAttribute::elaborate_args(Entity*ent, ScopeBase*scope, const VType*ltype)
@@ -678,7 +728,7 @@ const VType*ExpConcat::fit_type(Entity*ent, ScopeBase*scope, const VTypeArray*at
 
 	    if(const VTypeArray*arr = dynamic_cast<const VTypeArray*>(types[i])) {
 		types[i] = arr->element_type();
-		ivl_assert(*this, arr->dimensions() == 1);
+		ivl_assert(*this, arr->dimensions().size() == 1);
 		const VTypeArray::range_t&dim = arr->dimension(0);
 		sizes[i] = new ExpArithmetic(ExpArithmetic::MINUS, dim.msb(), dim.lsb());
 	    } else {
@@ -733,7 +783,7 @@ int ExpConcat::elaborate_expr_array_(Entity*ent, ScopeBase*scope, const VTypeArr
       int errors = 0;
 
 	// For now, only support single-dimension arrays here.
-      ivl_assert(*this, atype->dimensions() == 1);
+      ivl_assert(*this, atype->dimensions().size() == 1);
 
       const VType*type1 = operand1_->fit_type(ent, scope, atype);
       ivl_assert(*this, type1);
@@ -791,55 +841,23 @@ int ExpConditional::case_t::elaborate_expr(Entity*ent, ScopeBase*scope, const VT
 
 const VType*ExpFunc::probe_type(Entity*ent, ScopeBase*scope) const
 {
-      SubprogramHeader*prog = def_;
+      if(!def_)
+          def_ = match_signature(ent, scope);
 
-      if(!prog) {
-          list<const VType*> arg_types;
-
-          for(vector<Expression*>::const_iterator it = argv_.begin();
-                  it != argv_.end(); ++it) {
-              arg_types.push_back((*it)->probe_type(ent, scope));
-          }
-
-          prog = scope->match_subprogram(name_, &arg_types);
-
-          if(!prog)
-              prog = library_match_subprogram(name_, &arg_types);
-
-          if(!prog) {
-              cerr << get_fileline() << ": sorry: could not find function ";
-              emit_subprogram_sig(cerr, name_, arg_types);
-              cerr << endl;
-              ivl_assert(*this, false);
-          }
-      }
-
-      return prog->peek_return_type();
+      return def_ ? def_->exact_return_type(argv_, ent, scope) : NULL;
 }
 
 int ExpFunc::elaborate_expr(Entity*ent, ScopeBase*scope, const VType*)
 {
       int errors = 0;
 
-      ivl_assert(*this, def_ == 0);   // do not elaborate twice
+      if(def_)
+          return 0;
 
-      // Create a list of argument types to find a matching subprogram
-      list<const VType*> arg_types;
-      for(vector<Expression*>::iterator it = argv_.begin();
-              it != argv_.end(); ++it)
-          arg_types.push_back((*it)->probe_type(ent, scope));
-
-      def_ = scope->match_subprogram(name_, &arg_types);
+      def_ = match_signature(ent, scope);
 
       if(!def_)
-            def_ = library_match_subprogram(name_, &arg_types);
-
-      if(!def_) {
-            cerr << get_fileline() << ": error: could not find function ";
-            emit_subprogram_sig(cerr, name_, arg_types);
-            cerr << endl;
-            return 1;
-      }
+          return 1;
 
 	// Elaborate arguments
       for (size_t idx = 0; idx < argv_.size(); ++idx) {
@@ -859,7 +877,7 @@ int ExpFunc::elaborate_expr(Entity*ent, ScopeBase*scope, const VType*)
 
 const VType* ExpFunc::fit_type(Entity*ent, ScopeBase*scope, const VTypeArray*) const
 {
-      return probe_type(ent, scope);
+    return probe_type(ent, scope);
 }
 
 const VType* ExpInteger::probe_type(Entity*, ScopeBase*) const
diff --git a/vhdlpp/expression_emit.cc b/vhdlpp/expression_emit.cc
index f490cf4dd..a3d6e77e0 100644
--- a/vhdlpp/expression_emit.cc
+++ b/vhdlpp/expression_emit.cc
@@ -140,7 +140,7 @@ int ExpAggregate::emit_array_(ostream&out, Entity*ent, ScopeBase*scope, const VT
 
 	// Special case: The aggregate is a single "others" item.
       if (aggregate_.size() == 1 && aggregate_[0].choice->others()) {
-	    assert(atype->dimensions() == 1);
+	    assert(atype->dimensions().size() == 1);
 
 	    const VTypeArray::range_t&rang = atype->dimension(0);
 	    assert(! rang.is_box());
@@ -978,7 +978,7 @@ int ExpString::emit(ostream& out, Entity*ent, ScopeBase*scope) const
 int ExpString::emit_as_array_(ostream& out, Entity*, ScopeBase*, const VTypeArray*arr) const
 {
       int errors = 0;
-      assert(arr->dimensions() == 1);
+      assert(arr->dimensions().size() == 1);
 
       const VTypePrimitive*etype = dynamic_cast<const VTypePrimitive*> (arr->basic_type());
       assert(etype);
@@ -1048,6 +1048,15 @@ int ExpUNot::emit(ostream&out, Entity*ent, ScopeBase*scope) const
       return errors;
 }
 
+int ExpUMinus::emit(ostream&out, Entity*ent, ScopeBase*scope) const
+{
+      int errors = 0;
+      out << "-(";
+      errors += emit_operand1(out, ent, scope);
+      out << ")";
+      return errors;
+}
+
 int ExpCast::emit(ostream&out, Entity*ent, ScopeBase*scope) const
 {
       int errors = 0;
diff --git a/vhdlpp/expression_evaluate.cc b/vhdlpp/expression_evaluate.cc
index 97a1e4470..56b2b7eec 100644
--- a/vhdlpp/expression_evaluate.cc
+++ b/vhdlpp/expression_evaluate.cc
@@ -85,7 +85,7 @@ bool ExpAttribute::test_array_type(const VType*type) const
           return false;
       }
 
-      if (arr->dimensions() > 1) {
+      if (arr->dimensions().size() > 1) {
           cerr << endl << get_fileline() << ": error: "
               << "Cannot apply the '" << name_
               << " attribute to multidimensional arrays" << endl;
@@ -144,19 +144,6 @@ bool ExpName::evaluate(Entity*ent, ScopeBase*scope, int64_t&val) const
           return false;
       }
 
-      if (ent) {
-          const InterfacePort*gen = ent->find_generic(name_);
-          if (gen) {
-              // Evaluate the default expression and use that.
-              if (gen->expr && gen->expr->evaluate(ent, scope, val))
-                  return true;
-
-              cerr << get_fileline() << ": sorry: I could not evaluate "
-                   << "generic override." << endl;
-              return false;
-          }
-      }
-
       if (scope) {
           const VType*type;
           Expression*exp;
diff --git a/vhdlpp/expression_stream.cc b/vhdlpp/expression_stream.cc
index 43756922a..f9f6f40e5 100644
--- a/vhdlpp/expression_stream.cc
+++ b/vhdlpp/expression_stream.cc
@@ -327,6 +327,13 @@ void ExpUNot::write_to_stream(ostream&fd) const
       write_to_stream_operand1(fd);
 }
 
+void ExpUMinus::write_to_stream(ostream&fd) const
+{
+      fd << "-(";
+      write_to_stream_operand1(fd);
+      fd << ")";
+}
+
 void ExpCast::write_to_stream(ostream&fd) const
 {
       // Type casting is introduced only for a few specific cases in
diff --git a/vhdlpp/library.cc b/vhdlpp/library.cc
index fb015feab..5dd06d58b 100644
--- a/vhdlpp/library.cc
+++ b/vhdlpp/library.cc
@@ -25,6 +25,7 @@
 # include  "compiler.h"
 # include  "package.h"
 # include  "std_types.h"
+# include  "std_funcs.h"
 # include  <fstream>
 # include  <list>
 # include  <map>
@@ -110,7 +111,7 @@ static string make_library_package_path(perm_string lib_name, perm_string name)
 }
 
 static void import_ieee(void);
-static void import_ieee_use(ActiveScope*res, perm_string package, perm_string name);
+static void import_ieee_use(const YYLTYPE&loc, ActiveScope*res, perm_string package, perm_string name);
 static void import_std_use(const YYLTYPE&loc, ActiveScope*res, perm_string package, perm_string name);
 
 static void dump_library_package(ostream&file, perm_string lname, perm_string pname, Package*pack)
@@ -242,7 +243,7 @@ void library_use(const YYLTYPE&loc, ActiveScope*res,
 
 	// Special case handling for the IEEE library.
       if (use_library == "ieee") {
-	    import_ieee_use(res, use_package, use_name);
+	    import_ieee_use(loc, res, use_package, use_name);
 	    return;
       }
 	// Special case handling for the STD library.
@@ -312,8 +313,30 @@ static void import_ieee_use_std_logic_1164(ActiveScope*res, perm_string name)
       }
 }
 
-static void import_ieee_use_std_logic_arith(ActiveScope*, perm_string)
+static void import_ieee_use_std_logic_misc(ActiveScope*, perm_string name)
 {
+      bool all_flag = name=="all";
+      list<InterfacePort*>*args;
+
+      if (all_flag || name == "or_reduce") {
+            /* function or_reduce(arg : std_logic_vector) return std_logic;
+            */
+            args = new list<InterfacePort*>();
+            args->push_back(new InterfacePort(&primitive_STDLOGIC_VECTOR));
+            register_std_subprogram(new SubprogramBuiltin(perm_string::literal("or_reduce"),
+                                                perm_string::literal("|"),
+                                                args, &primitive_STDLOGIC));
+      }
+
+      if (all_flag || name == "and_reduce") {
+            /* function and_reduce(arg : std_logic_vector) return std_logic;
+            */
+            args = new list<InterfacePort*>();
+            args->push_back(new InterfacePort(&primitive_STDLOGIC_VECTOR));
+            register_std_subprogram(new SubprogramBuiltin(perm_string::literal("and_reduce"),
+                                                perm_string::literal("&"),
+                                                args, &primitive_STDLOGIC));
+      }
 }
 
 static void import_ieee_use_numeric_bit(ActiveScope*res, perm_string name)
@@ -340,7 +363,7 @@ static void import_ieee_use_numeric_std(ActiveScope*res, perm_string name)
       }
 }
 
-static void import_ieee_use(ActiveScope*res, perm_string package, perm_string name)
+static void import_ieee_use(const YYLTYPE&loc, ActiveScope*res, perm_string package, perm_string name)
 {
       if (package == "std_logic_1164") {
 	    import_ieee_use_std_logic_1164(res, name);
@@ -348,10 +371,20 @@ static void import_ieee_use(ActiveScope*res, perm_string package, perm_string na
       }
 
       if (package == "std_logic_arith") {
-	    import_ieee_use_std_logic_arith(res, name);
+            // arithmetic operators for std_logic_vector
 	    return;
       }
 
+      if (package == "std_logic_misc") {
+            import_ieee_use_std_logic_misc(res, name);
+            return;
+      }
+
+      if (package == "std_logic_unsigned") {
+            // arithmetic operators for std_logic_vector
+            return;
+      }
+
       if (package == "numeric_bit") {
 	    import_ieee_use_numeric_bit(res, name);
 	    return;
@@ -361,9 +394,11 @@ static void import_ieee_use(ActiveScope*res, perm_string package, perm_string na
 	    import_ieee_use_numeric_std(res, name);
 	    return;
       }
+
+      cerr << "Warning: Package ieee." << package.str() <<" is not yet supported" << endl;
 }
 
-static void import_std_use(const YYLTYPE&loc, ActiveScope*res, perm_string package, perm_string name)
+static void import_std_use(const YYLTYPE&loc, ActiveScope*res, perm_string package, perm_string /*name*/)
 {
       if (package == "standard") {
 	    // do nothing
@@ -375,7 +410,7 @@ static void import_std_use(const YYLTYPE&loc, ActiveScope*res, perm_string packa
             res->use_name(type_FILE_OPEN_STATUS.peek_name(),  &type_FILE_OPEN_STATUS);
 	    return;
       } else {
-	    sorrymsg(loc, "package %s of library %s not yet supported", package.str(), name.str());
+            cerr << "Warning: Package std." << package.str() <<" is not yet supported" << endl;
 	    return;
       }
 }
diff --git a/vhdlpp/parse.y b/vhdlpp/parse.y
index 82ccde7e3..6b4c13e5d 100644
--- a/vhdlpp/parse.y
+++ b/vhdlpp/parse.y
@@ -2484,11 +2484,6 @@ shift_expression
       }
   ;
 
-sign
-  : '+'
-  | '-'
-  ;
-
 signal_declaration_assign_opt
   : VASSIGN expression { $$ = $2; }
   |                    { $$ = 0;  }
@@ -2514,10 +2509,10 @@ signal_declaration_assign_opt
  * list fixes up the associations.
  */
 simple_expression
-  : sign simple_expression_2
-      { sorrymsg(@1, "Unary expression +- not supported.\n");
-	$$ = $2;
-      }
+  : '-' simple_expression_2
+      { $$ = new ExpUMinus($2); }
+  | '+' simple_expression_2
+      { $$ = $2; }
   | simple_expression_2
       { $$ = $1; }
   ;
diff --git a/vhdlpp/parse_misc.cc b/vhdlpp/parse_misc.cc
index a26eac818..f1d86184d 100644
--- a/vhdlpp/parse_misc.cc
+++ b/vhdlpp/parse_misc.cc
@@ -77,7 +77,7 @@ static const VType* calculate_subtype_array(const YYLTYPE&loc, const char*base_n
       const VType*base_type = parse_type_by_name(lex_strings.make(base_name));
 
       if (base_type == 0) {
-	    errormsg(loc, "Unable to find base type %s of array.\n", base_name);
+	    errormsg(loc, "Unable to find array base type '%s'.\n", base_name);
 	    return 0;
       }
 
@@ -97,7 +97,7 @@ static const VType* calculate_subtype_array(const YYLTYPE&loc, const char*base_n
 	    vector<VTypeArray::range_t> range (base_array->dimensions());
 
 	      // For now, I only know how to handle 1 dimension
-	    assert(base_array->dimensions() == 1);
+	    assert(base_array->dimensions().size() == 1);
 
 	    range[0] = VTypeArray::range_t(array_left, array_right, downto);
 
@@ -141,7 +141,7 @@ const VType* calculate_subtype_range(const YYLTYPE&loc, const char*base_name,
       const VType*base_type = parse_type_by_name(lex_strings.make(base_name));
 
       if (base_type == 0) {
-	    errormsg(loc, "Unable to find base type %s of range.\n", base_name);
+	    errormsg(loc, "Unable to find range base type '%s'.\n", base_name);
 	    return 0;
       }
 
diff --git a/vhdlpp/std_funcs.cc b/vhdlpp/std_funcs.cc
index fa417904e..e08e0c669 100644
--- a/vhdlpp/std_funcs.cc
+++ b/vhdlpp/std_funcs.cc
@@ -24,7 +24,7 @@
 
 static std::map<perm_string,SubHeaderList> std_subprograms;
 
-static inline void register_std_subprogram(SubprogramHeader*header)
+void register_std_subprogram(SubprogramHeader*header)
 {
     std_subprograms[header->name()].push_back(header);
 }
@@ -68,28 +68,51 @@ class SubprogramSizeCast : public SubprogramStdHeader {
           : SubprogramStdHeader(nam, NULL, target) {
           ports_ = new list<InterfacePort*>();
           ports_->push_back(new InterfacePort(base));
-          ports_->push_back(new InterfacePort(&primitive_INTEGER));
+          ports_->push_back(new InterfacePort(&primitive_NATURAL));
       }
 
-      int emit_name(const std::vector<Expression*>&argv,
-                    std::ostream&out, Entity*ent, ScopeBase*scope) const {
-          int64_t use_size;
-          bool rc = argv[1]->evaluate(ent, scope, use_size);
-
-          if(!rc) {
-              cerr << get_fileline() << ": sorry: Could not evaluate the "
-                   << "expression size. Size casting impossible." << endl;
-              return 1;
-          }
-
-          out << use_size << "'";
+      int emit_name(const std::vector<Expression*>&,
+                    std::ostream&, Entity*, ScopeBase*) const {
           return 0;
       }
 
       int emit_args(const std::vector<Expression*>&argv,
                     std::ostream&out, Entity*ent, ScopeBase*scope) const {
+          int64_t new_size, old_size;
 
-          return argv[0]->emit(out, ent, scope);
+          const VType*type = argv[0]->probe_type(ent, scope);
+
+          if(!type) {
+              cerr << get_fileline() << ": sorry: Could not determine "
+                   << "the argument type. Size casting impossible." << endl;
+              return 1;
+          }
+
+          old_size = type->get_width(scope);
+
+          if(old_size <= 0) {
+              cerr << get_fileline() << ": sorry: Could not determine "
+                   << "the argument size. Size casting impossible." << endl;
+              return 1;
+          }
+
+          if(!argv[1]->evaluate(ent, scope, new_size)) {
+              cerr << get_fileline() << ": sorry: Could not evaluate the requested"
+                   << "expression size. Size casting impossible." << endl;
+              return 1;
+          }
+
+
+          out << new_size << "'(" << old_size << "'(";
+
+          if(const VTypeArray*arr = dynamic_cast<const VTypeArray*>(type))
+                out << (arr->signed_vector() ? "$signed" : "$unsigned");
+
+          out << "(";
+          bool res = argv[0]->emit(out, ent, scope);
+          out << ")))";
+
+          return res;
       }
 };
 
@@ -187,7 +210,13 @@ void preload_std_funcs(void)
        have to do anything for that to work.
     */
     args = new list<InterfacePort*>();
-    args->push_back(new InterfacePort(&primitive_STDLOGIC_VECTOR));
+    args->push_back(new InterfacePort(&primitive_SIGNED));
+    register_std_subprogram(new SubprogramBuiltin(perm_string::literal("std_logic_vector"),
+                                           empty_perm_string,
+                                           args, &primitive_STDLOGIC_VECTOR));
+
+    args = new list<InterfacePort*>();
+    args->push_back(new InterfacePort(&primitive_UNSIGNED));
     register_std_subprogram(new SubprogramBuiltin(perm_string::literal("std_logic_vector"),
                                            empty_perm_string,
                                            args, &primitive_STDLOGIC_VECTOR));
@@ -215,6 +244,13 @@ void preload_std_funcs(void)
      * function shift_right (arg: signed; count: natural) return signed;
      */
     args = new list<InterfacePort*>();
+    args->push_back(new InterfacePort(&primitive_UNSIGNED));
+    args->push_back(new InterfacePort(&primitive_NATURAL));
+    register_std_subprogram(new SubprogramBuiltin(perm_string::literal("shift_right"),
+                                           perm_string::literal("$ivlh_shift_right"),
+                                           args, &primitive_UNSIGNED));
+
+    args = new list<InterfacePort*>();
     args->push_back(new InterfacePort(&primitive_SIGNED));
     args->push_back(new InterfacePort(&primitive_NATURAL));
     register_std_subprogram(new SubprogramBuiltin(perm_string::literal("shift_right"),
@@ -224,12 +260,16 @@ void preload_std_funcs(void)
     /* function resize
      */
     register_std_subprogram(new SubprogramSizeCast(perm_string::literal("resize"),
-                &primitive_STDLOGIC_VECTOR, &primitive_STDLOGIC_VECTOR));
+                &primitive_UNSIGNED, &primitive_UNSIGNED));
+
+    register_std_subprogram(new SubprogramSizeCast(perm_string::literal("resize"),
+                &primitive_SIGNED, &primitive_SIGNED));
 
     /* std_logic_arith library
      * function conv_std_logic_vector(arg: integer; size: integer) return std_logic_vector;
      */
-    register_std_subprogram(new SubprogramSizeCast(perm_string::literal("conv_std_logic_vector"),
+    register_std_subprogram(new SubprogramSizeCast(
+                perm_string::literal("conv_std_logic_vector"),
                 &primitive_INTEGER, &primitive_STDLOGIC_VECTOR));
 
     /* numeric_bit library
diff --git a/vhdlpp/std_funcs.h b/vhdlpp/std_funcs.h
index f3a904d44..8569b2424 100644
--- a/vhdlpp/std_funcs.h
+++ b/vhdlpp/std_funcs.h
@@ -28,6 +28,9 @@ void preload_std_funcs();
 // Destroys subprogram headers for standard VHDL library functions.
 void delete_std_funcs();
 
+// Adds a subprogram to the standard library subprogram set
+void register_std_subprogram(SubprogramHeader*header);
+
 // Returns subprogram header for a requested function or NULL if it does not exist.
 SubHeaderList find_std_subprogram(perm_string name);
 
diff --git a/vhdlpp/subprogram.cc b/vhdlpp/subprogram.cc
index bd7d832cc..d06917a31 100644
--- a/vhdlpp/subprogram.cc
+++ b/vhdlpp/subprogram.cc
@@ -172,6 +172,24 @@ const VType*SubprogramHeader::peek_param_type(int idx) const
       return NULL;
 }
 
+const VType*SubprogramHeader::exact_return_type(const std::vector<Expression*>&argv, Entity*ent, ScopeBase*scope)
+{
+    const VTypeArray*orig_ret = dynamic_cast<const VTypeArray*>(return_type_);
+
+    if(!orig_ret)
+        return return_type_;
+
+    const VTypeArray*arg = dynamic_cast<const VTypeArray*>(argv[0]->fit_type(ent, scope, orig_ret));
+
+    if(!arg)
+        return return_type_;
+
+    VTypeArray*ret = new VTypeArray(orig_ret->element_type(), arg->dimensions(), orig_ret->signed_vector());
+    ret->set_parent_type(orig_ret);
+
+    return ret;
+}
+
 bool SubprogramHeader::unbounded() const {
     if(return_type_ && return_type_->is_unbounded())
        return true;
diff --git a/vhdlpp/subprogram.h b/vhdlpp/subprogram.h
index d06f82461..a03b8da92 100644
--- a/vhdlpp/subprogram.h
+++ b/vhdlpp/subprogram.h
@@ -80,6 +80,10 @@ class SubprogramHeader : public LineInfo {
       const VType*peek_param_type(int idx) const;
       const VType*peek_return_type() const { return return_type_; }
 
+	// Computes the exact return type (e.g. std_logic_vector(7 downto 0)
+	// instead of generic std_logic_vector)
+      virtual const VType*exact_return_type(const std::vector<Expression*>&, Entity*, ScopeBase*);
+
       inline void set_package(const Package*pkg) { assert(!package_); package_ = pkg; }
       inline const Package*get_package() const { return package_; }
 
diff --git a/vhdlpp/vtype.h b/vhdlpp/vtype.h
index 7c5ec3aac..4f34c62ac 100644
--- a/vhdlpp/vtype.h
+++ b/vhdlpp/vtype.h
@@ -226,7 +226,7 @@ class VTypeArray : public VType {
       void show(std::ostream&) const;
       int get_width(ScopeBase*scope) const;
 
-      inline size_t dimensions() const { return ranges_.size(); };
+      const std::vector<range_t>&dimensions() const { return ranges_; };
       const range_t&dimension(size_t idx) const
       { return ranges_[idx]; }
 
@@ -253,6 +253,8 @@ class VTypeArray : public VType {
 	// To handle subtypes
       inline void set_parent_type(const VTypeArray*parent) { parent_ = parent; }
 
+      const VTypeArray*get_parent_type() const { return parent_; }
+
 	// Wherever it is possible, replaces range lsb & msb expressions with
 	// constant integers.
       void evaluate_ranges(ScopeBase*scope);
diff --git a/vhdlpp/vtype_emit.cc b/vhdlpp/vtype_emit.cc
index 8327af50c..81807fa4b 100644
--- a/vhdlpp/vtype_emit.cc
+++ b/vhdlpp/vtype_emit.cc
@@ -65,7 +65,7 @@ int VTypeArray::emit_def(ostream&out, perm_string name) const
       const VTypePrimitive*base = dynamic_cast<const VTypePrimitive*> (raw_base);
 
       if (base) {
-	    assert(dimensions() == 1);
+	    assert(dimensions().size() == 1);
 
 	    // If this is a string type without any boundaries specified, then
 	    // there is a direct counterpart in SV called.. 'string'
@@ -127,7 +127,7 @@ int VTypeArray::emit_with_dims_(std::ostream&out, bool packed, perm_string name)
 	        name_emitted = true;
 	    }
 
-	    for(unsigned i = 0; i < cur->dimensions(); ++i) {
+	    for(unsigned i = 0; i < cur->dimensions().size(); ++i) {
 	        if(cur->dimension(i).is_box() && !name_emitted) {
 	            emit_name(out, name);
 	            name_emitted = true;
diff --git a/vhdlpp/vtype_match.cc b/vhdlpp/vtype_match.cc
index a4a49b1b5..c99a2fd78 100644
--- a/vhdlpp/vtype_match.cc
+++ b/vhdlpp/vtype_match.cc
@@ -70,7 +70,15 @@ bool VTypeArray::type_match(const VType*that) const
 
       // Check if both arrays are of the same size
       if(const VTypeArray*arr = dynamic_cast<const VTypeArray*>(that)) {
-          if(!element_type()->type_match(arr->element_type()))
+          const VTypeArray*this_parent = this;
+          while(const VTypeArray*tmp = this_parent->get_parent_type())
+              this_parent = tmp;
+
+          const VTypeArray*that_parent = arr;
+          while(const VTypeArray*tmp = that_parent->get_parent_type())
+              that_parent = tmp;
+
+          if(this_parent != that_parent)
               return false;
 
           int this_width = get_width(NULL);