diff --git a/lib/puppet/pops/validation/checker4_0.rb b/lib/puppet/pops/validation/checker4_0.rb
index 8ea140f1f..698b95645 100644
--- a/lib/puppet/pops/validation/checker4_0.rb
+++ b/lib/puppet/pops/validation/checker4_0.rb
@@ -1,555 +1,546 @@
 # A Validator validates a model.
 #
 # Validation is performed on each model element in isolation. Each method should validate the model element's state
 # but not validate its referenced/contained elements except to check their validity in their respective role.
 # The intent is to drive the validation with a tree iterator that visits all elements in a model.
 #
 #
 # TODO: Add validation of multiplicities - this is a general validation that can be checked for all
 #       Model objects via their metamodel. (I.e an extra call to multiplicity check in polymorph check).
 #       This is however mostly valuable when validating model to model transformations, and is therefore T.B.D
 #
 class Puppet::Pops::Validation::Checker4_0
   Issues = Puppet::Pops::Issues
   Model = Puppet::Pops::Model
 
   attr_reader :acceptor
   # Initializes the validator with a diagnostics producer. This object must respond to
   # `:will_accept?` and `:accept`.
   #
   def initialize(diagnostics_producer)
     @@check_visitor       ||= Puppet::Pops::Visitor.new(nil, "check", 0, 0)
     @@rvalue_visitor      ||= Puppet::Pops::Visitor.new(nil, "rvalue", 0, 0)
     @@hostname_visitor    ||= Puppet::Pops::Visitor.new(nil, "hostname", 1, 2)
     @@assignment_visitor  ||= Puppet::Pops::Visitor.new(nil, "assign", 0, 1)
     @@query_visitor       ||= Puppet::Pops::Visitor.new(nil, "query", 0, 0)
     @@top_visitor         ||= Puppet::Pops::Visitor.new(nil, "top", 1, 1)
     @@relation_visitor    ||= Puppet::Pops::Visitor.new(nil, "relation", 1, 1)
 
     @acceptor = diagnostics_producer
   end
 
   # Validates the entire model by visiting each model element and calling `check`.
   # The result is collected (or acted on immediately) by the configured diagnostic provider/acceptor
   # given when creating this Checker.
   #
   def validate(model)
     # tree iterate the model, and call check for each element
     check(model)
     model.eAllContents.each {|m| check(m) }
   end
 
   # Performs regular validity check
   def check(o)
     @@check_visitor.visit_this_0(self, o)
   end
 
   # Performs check if this is a vaid hostname expression
   # @param single_feature_name [String, nil] the name of a single valued hostname feature of the value's container. e.g. 'parent'
   def hostname(o, semantic, single_feature_name = nil)
     @@hostname_visitor.visit_this_2(self, o, semantic, single_feature_name)
   end
 
   # Performs check if this is valid as a query
   def query(o)
     @@query_visitor.visit_this_0(self, o)
   end
 
   # Performs check if this is valid as a relationship side
   def relation(o, container)
     @@relation_visitor.visit_this_1(self, o, container)
   end
 
   # Performs check if this is valid as a rvalue
   def rvalue(o)
     @@rvalue_visitor.visit_this_0(self, o)
   end
 
   # Performs check if this is valid as a container of a definition (class, define, node)
   def top(o, definition)
     @@top_visitor.visit_this_1(self, o, definition)
   end
 
   # Checks the LHS of an assignment (is it assignable?).
   # If args[0] is true, assignment via index is checked.
   #
   def assign(o, via_index = false)
     @@assignment_visitor.visit_this_1(self, o, via_index)
   end
 
   #---ASSIGNMENT CHECKS
 
   def assign_VariableExpression(o, via_index)
     varname_string = varname_to_s(o.expr)
     if varname_string =~ /^[0-9]+$/
       acceptor.accept(Issues::ILLEGAL_NUMERIC_ASSIGNMENT, o, :varname => varname_string)
     end
     # Can not assign to something in another namespace (i.e. a '::' in the name is not legal)
     if acceptor.will_accept? Issues::CROSS_SCOPE_ASSIGNMENT
       if varname_string =~ /::/
         acceptor.accept(Issues::CROSS_SCOPE_ASSIGNMENT, o, :name => varname_string)
       end
     end
     # TODO: Could scan for reassignment of the same variable if done earlier in the same container
     #       Or if assigning to a parameter (more work).
     # TODO: Investigate if there are invalid cases for += assignment
   end
 
   def assign_AccessExpression(o, via_index)
     # Are indexed assignments allowed at all ? $x[x] = '...'
     if acceptor.will_accept? Issues::ILLEGAL_INDEXED_ASSIGNMENT
       acceptor.accept(Issues::ILLEGAL_INDEXED_ASSIGNMENT, o)
     else
       # Then the left expression must be assignable-via-index
       assign(o.left_expr, true)
     end
   end
 
   def assign_Object(o, via_index)
     # Can not assign to anything else (differentiate if this is via index or not)
     # i.e. 10 = 'hello' vs. 10['x'] = 'hello' (the root is reported as being in error in both cases)
     #
     acceptor.accept(via_index ? Issues::ILLEGAL_ASSIGNMENT_VIA_INDEX : Issues::ILLEGAL_ASSIGNMENT, o)
   end
 
   #---CHECKS
 
   def check_Object(o)
   end
 
   def check_Factory(o)
     check(o.current)
   end
 
   def check_AccessExpression(o)
-    # Check multiplicity of keys
-    case o.left_expr
-    when Model::QualifiedName
-      # allows many keys, but the name should really be a QualifiedReference
-      # acceptor.accept(Issues::DEPRECATED_NAME_AS_TYPE, o, :name => o.value)
-      # OK in 4.x since a name evaluates to a String, and String[] is supported
-      # Also allows many
-    when Model::QualifiedReference
-      # ok, allows many - this is a type / resource reference
-
-    else
-      # i.e. for any other expression that may produce an array or hash
-#      if o.keys.size > 1
-#        acceptor.accept(Issues::UNSUPPORTED_RANGE, o, :count => o.keys.size)
-#      end
-      # Range is ok, multiple keys supported by many LHS types (checked at runtime)
-      # TODO: can statically check key size for some types Name & String 1-2, Array 1,2, Hash 1-many, etc
-      # (but is captured as RT error)
-      if o.keys.size < 1
-        acceptor.accept(Issues::MISSING_INDEX, o)
-      end
+    # Only min range is checked, all other checks are RT checks as they depend on the resulting type
+    # of the LHS.
+    if o.keys.size < 1
+      acceptor.accept(Issues::MISSING_INDEX, o)
     end
   end
 
   def check_AssignmentExpression(o)
     acceptor.accept(Issues::UNSUPPORTED_OPERATOR, o, {:operator => o.operator}) unless [:'=', :'+=', :'-='].include? o.operator
     assign(o.left_expr)
     rvalue(o.right_expr)
   end
 
   # Checks that operation with :+> is contained in a ResourceOverride or Collector.
   #
   # Parent of an AttributeOperation can be one of:
   # * CollectExpression
   # * ResourceOverride
   # * ResourceBody (ILLEGAL this is a regular resource expression)
   # * ResourceDefaults (ILLEGAL)
   #
   def check_AttributeOperation(o)
     if o.operator == :'+>'
       # Append operator use is constrained
       parent = o.eContainer
       unless parent.is_a?(Model::CollectExpression) || parent.is_a?(Model::ResourceOverrideExpression)
         acceptor.accept(Issues::ILLEGAL_ATTRIBUTE_APPEND, o, {:name=>o.attribute_name, :parent=>parent})
       end
     end
     rvalue(o.value_expr)
   end
 
   def check_BinaryExpression(o)
     rvalue(o.left_expr)
     rvalue(o.right_expr)
   end
 
   def check_CallNamedFunctionExpression(o)
     unless o.functor_expr.is_a? Model::QualifiedName
       acceptor.accept(Issues::ILLEGAL_EXPRESSION, o.functor_expr, :feature => 'function name', :container => o)
     end
   end
 
   def check_MethodCallExpression(o)
     unless o.functor_expr.is_a? Model::QualifiedName
       acceptor.accept(Issues::ILLEGAL_EXPRESSION, o.functor_expr, :feature => 'function name', :container => o)
     end
   end
 
   def check_CaseExpression(o)
     rvalue(o.test)
     # There should only be one LiteralDefault case option value
     # TODO: Implement this check
   end
 
   def check_CaseOption(o)
     o.values.each { |v| rvalue(v) }
   end
 
   def check_CollectExpression(o)
     unless o.type_expr.is_a? Model::QualifiedReference
       acceptor.accept(Issues::ILLEGAL_EXPRESSION, o.type_expr, :feature=> 'type name', :container => o)
     end
 
     # If a collect expression tries to collect exported resources and storeconfigs is not on
     # then it will not work... This was checked in the parser previously. This is a runtime checking
     # thing as opposed to a language thing.
     if acceptor.will_accept?(Issues::RT_NO_STORECONFIGS) && o.query.is_a?(Model::ExportedQuery)
       acceptor.accept(Issues::RT_NO_STORECONFIGS, o)
     end
   end
 
   # Only used for function names, grammar should not be able to produce something faulty, but
   # check anyway if model is created programatically (it will fail in transformation to AST for sure).
   def check_NamedAccessExpression(o)
     name = o.right_expr
     unless name.is_a? Model::QualifiedName
       acceptor.accept(Issues::ILLEGAL_EXPRESSION, name, :feature=> 'function name', :container => o.eContainer)
     end
   end
 
   # for 'class' and 'define'
   def check_NamedDefinition(o)
     top(o.eContainer, o)
     if (acceptor.will_accept? Issues::NAME_WITH_HYPHEN) && o.name.include?('-')
       acceptor.accept(Issues::NAME_WITH_HYPHEN, o, {:name => o.name})
     end
   end
 
+  def check_IfExpression(o)
+    rvalue(o.test)
+  end
+
   def check_ImportExpression(o)
     o.files.each do |f|
       unless f.is_a? Model::LiteralString
         acceptor.accept(Issues::ILLEGAL_EXPRESSION, f, :feature => 'file name', :container => o)
       end
     end
   end
 
   def check_KeyedEntry(o)
     rvalue(o.key)
     rvalue(o.value)
     # In case there are additional things to forbid than non-rvalues
     # acceptor.accept(Issues::ILLEGAL_EXPRESSION, o.key, :feature => 'hash key', :container => o.eContainer)
   end
 
-  # A Lambda is a Definition, but it may appear in other scopes that top scope (Which check_Definition asserts).
+  # A Lambda is a Definition, but it may appear in other scopes than top scope (Which check_Definition asserts).
   #
   def check_LambdaExpression(o)
   end
 
+  def check_LiteralList(o)
+    o.values.each {|v| rvalue(v) }
+  end
+
   def check_NodeDefinition(o)
-    # Check that hostnames are valid hostnames (or regular expressons)
+    # Check that hostnames are valid hostnames (or regular expressions)
     hostname(o.host_matches, o)
     hostname(o.parent, o, 'parent') unless o.parent.nil?
     top(o.eContainer, o)
   end
 
   # Asserts that value is a valid QualifiedName. No additional checking is made, objects that use
   # a QualifiedName as a name should check the validity - this since a QualifiedName is used as a BARE WORD
   # and then additional chars may be valid (like a hyphen).
   #
   def check_QualifiedName(o)
     # Is this a valid qualified name?
     if o.value !~ Puppet::Pops::Patterns::NAME
       acceptor.accept(Issues::ILLEGAL_NAME, o, {:name=>o.value})
     end
   end
 
   # Checks that the value is a valid UpperCaseWord (a CLASSREF), and optionally if it contains a hypen.
   # DOH: QualifiedReferences are created with LOWER CASE NAMES at parse time
   def check_QualifiedReference(o)
     # Is this a valid qualified name?
     if o.value !~ Puppet::Pops::Patterns::CLASSREF
       acceptor.accept(Issues::ILLEGAL_CLASSREF, o, {:name=>o.value})
     elsif (acceptor.will_accept? Issues::NAME_WITH_HYPHEN) && o.value.include?('-')
       acceptor.accept(Issues::NAME_WITH_HYPHEN, o, {:name => o.value})
     end
   end
 
   def check_QueryExpression(o)
     query(o.expr) if o.expr  # is optional
   end
 
   def relation_Object(o, rel_expr)
     acceptor.accept(Issues::ILLEGAL_EXPRESSION, o, {:feature => o.eContainingFeature, :container => rel_expr})
   end
 
   def relation_AccessExpression(o, rel_expr); end
 
   def relation_CollectExpression(o, rel_expr); end
 
   def relation_VariableExpression(o, rel_expr); end
 
   def relation_LiteralString(o, rel_expr); end
 
   def relation_ConcatenatedStringExpression(o, rel_expr); end
 
   def relation_SelectorExpression(o, rel_expr); end
 
   def relation_CaseExpression(o, rel_expr); end
 
   def relation_ResourceExpression(o, rel_expr); end
 
   def relation_RelationshipExpression(o, rel_expr); end
 
   def check_Parameter(o)
     if o.name =~ /^[0-9]+$/
       acceptor.accept(Issues::ILLEGAL_NUMERIC_PARAMETER, o, :name => o.name)
     end
   end
 
   #relationship_side: resource
   #  | resourceref
   #  | collection
   #  | variable
   #  | quotedtext
   #  | selector
   #  | casestatement
   #  | hasharrayaccesses
 
   def check_RelationshipExpression(o)
     relation(o.left_expr, o)
     relation(o.right_expr, o)
   end
 
   def check_ResourceExpression(o)
     # A resource expression must have a lower case NAME as its type e.g. 'file { ... }'
     unless o.type_name.is_a? Model::QualifiedName
       acceptor.accept(Issues::ILLEGAL_EXPRESSION, o.type_name, :feature => 'resource type', :container => o)
     end
 
     # This is a runtime check - the model is valid, but will have runtime issues when evaluated
     # and storeconfigs is not set.
     if acceptor.will_accept?(Issues::RT_NO_STORECONFIGS) && o.exported
       acceptor.accept(Issues::RT_NO_STORECONFIGS_EXPORT, o)
     end
   end
 
   def check_ResourceDefaultsExpression(o)
     if o.form && o.form != :regular
       acceptor.accept(Issues::NOT_VIRTUALIZEABLE, o)
     end
   end
 
   # Transformation of SelectorExpression is limited to certain types of expressions.
   # This is probably due to constraints in the old grammar rather than any real concerns.
   def select_SelectorExpression(o)
     case o.left_expr
     when Model::CallNamedFunctionExpression
     when Model::AccessExpression
     when Model::VariableExpression
     when Model::ConcatenatedString
     else
       acceptor.accept(Issues::ILLEGAL_EXPRESSION, o.left_expr, :feature => 'left operand', :container => o)
     end
   end
 
   def check_UnaryExpression(o)
     rvalue(o.expr)
   end
 
   def check_UnlessExpression(o)
-    # TODO: Unless may not have an elsif
-    # TODO: 3.x unless may not have an else
+    rvalue(o.test)
+    # TODO: Unless may not have an else part that is an IfExpression (grammar denies this though)
   end
 
   def check_VariableExpression(o)
     # The expression must be a qualified name
     if !o.expr.is_a? Model::QualifiedName
       acceptor.accept(Issues::ILLEGAL_EXPRESSION, o, :feature => 'name', :container => o)
     else
       # Note, that if it later becomes illegal with hyphen in any name, this special check
       # can be skipped in favor of the check in QualifiedName, which is now not done if contained in
       # a VariableExpression
       name = o.expr.value
       if (acceptor.will_accept? Issues::VAR_WITH_HYPHEN) && name.include?('-')
         acceptor.accept(Issues::VAR_WITH_HYPHEN, o, {:name => name})
       end
     end
   end
 
   #--- HOSTNAME CHECKS
 
   # Transforms Array of host matching expressions into a (Ruby) array of AST::HostName
   def hostname_Array(o, semantic, single_feature_name)
     if single_feature_name
       acceptor.accept(Issues::ILLEGAL_EXPRESSION, o, {:feature=>single_feature_name, :container=>semantic})
     end
     o.each {|x| hostname(x, semantic, false) }
   end
 
   def hostname_String(o, semantic, single_feature_name)
     # The 3.x checker only checks for illegal characters - if matching /[^-\w.]/ the name is invalid,
     # but this allows pathological names like "a..b......c", "----"
     # TODO: Investigate if more illegal hostnames should be flagged.
     #
     if o =~ Puppet::Pops::Patterns::ILLEGAL_HOSTNAME_CHARS
       acceptor.accept(Issues::ILLEGAL_HOSTNAME_CHARS, semantic, :hostname => o)
     end
   end
 
   def hostname_LiteralValue(o, semantic, single_feature_name)
     hostname_String(o.value.to_s, o, single_feature_name)
   end
 
   def hostname_ConcatenatedString(o, semantic, single_feature_name)
     # Puppet 3.1. only accepts a concatenated string without interpolated expressions
     if the_expr = o.segments.index {|s| s.is_a?(Model::TextExpression) }
       acceptor.accept(Issues::ILLEGAL_HOSTNAME_INTERPOLATION, o.segments[the_expr].expr)
     elsif o.segments.size() != 1
       # corner case, bad model, concatenation of several plain strings
       acceptor.accept(Issues::ILLEGAL_HOSTNAME_INTERPOLATION, o)
     else
       # corner case, may be ok, but lexer may have replaced with plain string, this is
       # here if it does not
       hostname_String(o.segments[0], o.segments[0], false)
     end
   end
 
   def hostname_QualifiedName(o, semantic, single_feature_name)
     hostname_String(o.value.to_s, o, single_feature_name)
   end
 
   def hostname_QualifiedReference(o, semantic, single_feature_name)
     hostname_String(o.value.to_s, o, single_feature_name)
   end
 
   def hostname_LiteralNumber(o, semantic, single_feature_name)
     # always ok
   end
 
   def hostname_LiteralDefault(o, semantic, single_feature_name)
     # always ok
   end
 
   def hostname_LiteralRegularExpression(o, semantic, single_feature_name)
     # always ok
   end
 
   def hostname_Object(o, semantic, single_feature_name)
     acceptor.accept(Issues::ILLEGAL_EXPRESSION, o, {:feature=> single_feature_name || 'hostname', :container=>semantic})
   end
 
   #---QUERY CHECKS
 
   # Anything not explicitly allowed is flagged as error.
   def query_Object(o)
     acceptor.accept(Issues::ILLEGAL_QUERY_EXPRESSION, o)
   end
 
   # Puppet AST only allows == and !=
   #
   def query_ComparisonExpression(o)
     acceptor.accept(Issues::ILLEGAL_QUERY_EXPRESSION, o) unless [:'==', :'!='].include? o.operator
   end
 
   # Allows AND, OR, and checks if left/right are allowed in query.
   def query_BooleanExpression(o)
     query o.left_expr
     query o.right_expr
   end
 
   def query_ParenthesizedExpression(o)
     query(o.expr)
   end
 
   def query_VariableExpression(o); end
 
   def query_QualifiedName(o); end
 
   def query_LiteralNumber(o); end
 
   def query_LiteralString(o); end
 
   def query_LiteralBoolean(o); end
 
   #---RVALUE CHECKS
 
   # By default, all expressions are reported as being rvalues
   # Implement specific rvalue checks for those that are not.
   #
   def rvalue_Expression(o); end
 
   def rvalue_ImportExpression(o)          ; acceptor.accept(Issues::NOT_RVALUE, o) ; end
 
   def rvalue_BlockExpression(o)           ; acceptor.accept(Issues::NOT_RVALUE, o) ; end
 
 #  def rvalue_CaseExpression(o)            ; acceptor.accept(Issues::NOT_RVALUE, o) ; end
 
 #  def rvalue_IfExpression(o)              ; acceptor.accept(Issues::NOT_RVALUE, o) ; end
 
 #  def rvalue_UnlessExpression(o)          ; acceptor.accept(Issues::NOT_RVALUE, o) ; end
 
   def rvalue_ResourceExpression(o)        ; acceptor.accept(Issues::NOT_RVALUE, o) ; end
 
   def rvalue_ResourceDefaultsExpression(o); acceptor.accept(Issues::NOT_RVALUE, o) ; end
 
   def rvalue_ResourceOverrideExpression(o); acceptor.accept(Issues::NOT_RVALUE, o) ; end
 
   def rvalue_CollectExpression(o)         ; acceptor.accept(Issues::NOT_RVALUE, o) ; end
 
   def rvalue_Definition(o)                ; acceptor.accept(Issues::NOT_RVALUE, o) ; end
 
   def rvalue_NodeDefinition(o)            ; acceptor.accept(Issues::NOT_RVALUE, o) ; end
 
   def rvalue_UnaryExpression(o)           ; rvalue o.expr                 ; end
 
   #---TOP CHECK
 
   def top_NilClass(o, definition)
     # ok, reached the top, no more parents
   end
 
   def top_Object(o, definition)
     # fail, reached a container that is not top level
     acceptor.accept(Issues::NOT_TOP_LEVEL, definition)
   end
 
   def top_BlockExpression(o, definition)
     # ok, if this is a block representing the body of a class, or is top level
     top o.eContainer, definition
   end
 
   def top_HostClassDefinition(o, definition)
     # ok, stop scanning parents
   end
 
   def top_Program(o, definition)
     # ok
   end
 
   # A LambdaExpression is a BlockExpression, and this method is needed to prevent the polymorph method for BlockExpression
   # to accept a lambda.
   # A lambda can not iteratively create classes, nodes or defines as the lambda does not have a closure.
   #
   def top_LambdaExpression(o, definition)
     # fail, stop scanning parents
     acceptor.accept(Issues::NOT_TOP_LEVEL, definition)
   end
 
   #--- NON POLYMORPH, NON CHECKING CODE
 
   # Produces string part of something named, or nil if not a QualifiedName or QualifiedReference
   #
   def varname_to_s(o)
     case o
     when Model::QualifiedName
       o.value
     when Model::QualifiedReference
       o.value
     else
       nil
     end
   end
 end