NAME
Muldis::D::Ext::Bag - Muldis D extension for Bag specific operators
VERSION
This document is Muldis::D::Ext::Bag version 0.98.0.
PREFACE
This document is part of the Muldis D language specification, whose root document is Muldis::D; you should read that root document before you read this one, which provides subservient details.
DESCRIPTION
Muldis D has a mandatory core set of system-defined (eternally available) entities, which is referred to as the Muldis D core or the core; they are the minimal entities that all Muldis D implementations need to provide; they are mutually self-describing and are used to bootstrap the language; any entities outside the core, called Muldis D extensions, are non-mandatory and are defined in terms of the core or each other, but the reverse isn't true.
This current Bag document describes the system-defined Muldis D Bag Extension, which consists of generic operators that are specific to the Bag parameterized relation type, and said operators are short-hands for generic relational operators in the language core.
This current document does not describe the polymorphic operators that all types, or some types including core types, have defined over them; said operators are defined once for all types in Muldis::D::Core.
This documentation is pending.
SYSTEM-DEFINED BAG-CONCERNING FUNCTIONS
sys.std.Bag.cardinality
function sys.std.Bag.cardinality (NNInt <-- $topic : Bag)
This function is like sys.std.Core.Relation.cardinality but that it accounts for the greater-than-one multiplicity of values in its argument; it results in the sum of the count attribute of its argument. Note that this operation is also known as M#.
sys.std.Bag.has_member
function sys.std.Bag.has_member (Bool <-- $bag : Bag, $value : Universal)
This function is the same as sys.std.Set.has_member, including that matching of value is done against the value attribute, except that it works with a Bag rather than a Set. Note that this operation is also known as B∋.
sys.std.Bag.has_not_member
function sys.std.Bag.has_not_member (Bool <-- $bag : Bag, $value : Universal)
This function is exactly the same as sys.std.Bag.has_member except that it results in the opposite boolean value when given the same arguments. Note that this operation is also known as B∌.
sys.std.Bag.value_is_member
function sys.std.Bag.value_is_member (Bool <-- $value : Universal, $bag : Bag)
This function is an alias for sys.std.Bag.has_member. This function is the same as sys.std.Set.value_is_member, including that matching of value is done against the value attribute, except that it works with a Bag rather than a Set. Note that this operation is also known as B∈.
sys.std.Bag.value_is_not_member
function sys.std.Bag.value_is_not_member (Bool <-- $value : Universal, $bag : Bag)
This function is an alias for sys.std.Bag.has_not_member. This function is exactly the same as sys.std.Bag.value_is_member except that it results in the opposite boolean value when given the same arguments. Note that this operation is also known as B¬in;.
sys.std.Bag.count
function sys.std.Bag.count (NNInt <-- $bag : Bag, $value : Universal)
This function results in the multiplicity / count of occurrances of value in bag; if a tuple exists in bag whose value attribute is value, then the result is its count attribute; otherwise the result is zero.
sys.std.Bag.insertion
function sys.std.Bag.insertion (Bag <-- $bag : Bag, $value : Universal)
This function is the same as sys.std.Set.insertion as per has_member but that its result differs depending on whether value already exists in bag; if it does, then no new tuple is added, but the count attribute for the matching tuple is incremented by 1; if it does not, then a new tuple is added where its value is value and its count is 1. Actually this function differs in another way, such that it is semantically the single-tuple case of sys.std.Bag.union_sum, and is not the single-tuple case of sys.std.Bag.union (which is the direct analogy to set union).
sys.std.Bag.deletion
function sys.std.Bag.deletion (Bag <-- $bag : Bag, $value : Universal)
This function is the same as sys.std.Set.deletion as per has_member but that its result differs depending on what the count for any tuple matching value that already exists in bag is; if the count is greater than 1, then it is decremented by 1; if it is equal to 1, then the tuple whose value attribute is value is deleted.
sys.std.Bag.reduction
function sys.std.Bag.reduction (Universal <-- $topic : Bag, $func : ValRedFuncRef, $identity : Universal)
This function is the same as sys.std.Set.reduction, including that input values for the reduction come from the value attribute of topic, except that it works with a Bag rather than a Set; func is invoked extra times, where both its v1 and v2 arguments might be different instances of the same value having >= 2 multiplicity.
sys.std.Bag.maybe_reduction
function sys.std.Bag.maybe_reduction (Maybe <-- $topic : Bag, $func : ValRedFuncRef)
This function is to sys.std.Set.maybe_reduction as sys.std.Bag.reduction is to sys.std.Set.reduction.
sys.std.Bag.Set_from_Bag
function sys.std.Bag.Set_from_Bag (Set <-- $topic : Bag)
This function results in the Set that is the projection of the value attribute of its Bag argument.
sys.std.Bag.Bag_from_Set
function sys.std.Bag.Bag_from_Set (Bag <-- $topic : Set)
This function results in the Bag that is the extension of its Set argument with a new count attribute whose value for every tuple is 1.
sys.std.Bag.Bag_from_wrap
function sys.std.Bag.Bag_from_wrap (bag_of.Tuple <-- $topic : Relation)
This function results in a Bag whose value attribute is tuple-typed and that attribute's values are all the tuples of topic; it is a short-hand for a relational wrap of all attributes of topic such that the new tuple-valued attribute is named value, and then that result is extended with a count attribute whose value for every tuple is 1.
sys.std.Bag.Bag_from_cmpl_group
function sys.std.Bag.Bag_from_cmpl_group (bag_of.Tuple <-- $topic : Relation, $group_per : set_of.Name)
This function is like sys.std.Core.Relation.cardinality_per_group but that the count_attr_name is count and all the other attributes that would have been in the result are wrapped in a single tuple-valued attribute named value. This function is to cardinality_per_group what sys.std.Array.Array_from_wrap is to sys.std.Relation.rank.
sys.std.Bag.Bag_from_attr
function sys.std.Bag.Bag_from_attr (Bag <-- $topic : Relation, $name : Name)
This function results in a Bag consisting of all the values of the attribute of topic named by name. It is a short-hand for first doing a relational group on all attributes of topic besides name to produce a new relation-typed attribute, and then extending the result of the group with a new positive integer attribute whose values are the cardinality of the relation-valued attribute's values, and then doing a binary projection of the named attribute and the new integer attribute plus their renaming to value and count respectively.
sys.std.Bag.is_subset
function sys.std.Bag.is_subset (Bool <-- $topic : Bag, $other : Bag)
This function is like sys.std.Core.Relation.is_subset but that it accounts for the greater-than-one multiplicity of values in its arguments; this function returns Bool:true iff the multiplicity of each topic value is less than or equal to the multiplicity of its counterpart other value.
sys.std.Bag.is_not_subset
function sys.std.Bag.is_not_subset (Bool <-- $topic : Bag, $other : Bag)
This function is like sys.std.Core.Relation.is_not_subset as per is_subset.
sys.std.Bag.is_superset
function sys.std.Bag.is_superset (Bool <-- $topic : Bag, $other : Bag)
This function is an alias for sys.std.Bag.is_subset except that it transposes the topic and other arguments. This function is like sys.std.Core.Relation.is_superset but that it accounts for the greater-than-one multiplicity of values in its arguments; this function returns Bool:true iff the multiplicity of each topic value is greater than or equal to the multiplicity of its counterpart other value.
sys.std.Bag.is_not_superset
function sys.std.Bag.is_not_superset (Bool <-- $topic : Bag, $other : Bag)
This function is an alias for sys.std.Bag.is_not_subset except that it transposes the topic and other arguments. This function is like sys.std.Core.Relation.is_not_superset as per is_superset.
sys.std.Bag.is_proper_subset
function sys.std.Bag.is_proper_subset (Bool <-- $topic : Bag, $other : Bag)
This function is like sys.std.Relation.is_proper_subset as per is_subset. TODO: What is its definition?
sys.std.Bag.is_not_proper_subset
function sys.std.Bag.is_not_proper_subset (Bool <-- $topic : Bag, $other : Bag)
This function is like sys.std.Relation.is_not_proper_subset as per is_subset. TODO: What is its definition?
sys.std.Bag.is_proper_superset
function sys.std.Bag.is_proper_superset (Bool <-- $topic : Bag, $other : Bag)
This function is an alias for sys.std.Bag.is_proper_subset except that it transposes the topic and other arguments. This function is like sys.std.Relation.is_proper_superset as per is_superset.
sys.std.Bag.is_not_proper_superset
function sys.std.Bag.is_not_proper_superset (Bool <-- $topic : Bag, $other : Bag)
This function is an alias for sys.std.Bag.is_not_proper_subset except that it transposes the topic and other arguments. This function is like sys.std.Relation.is_not_proper_superset as per is_superset.
sys.std.Bag.union
function sys.std.Bag.union (Bag <-- $topic : set_of.Bag)
This function is like sys.std.Core.Relation.union but that it just looks at the value attribute of its argument elements when determining what element tuples correspond; then for each tuple in the result, its count attribute value is the maximum of the count attribute values of its corresponding input element tuples.
sys.std.Bag.union_sum
function sys.std.Bag.union_sum (Bag <-- $topic : bag_of.Bag)
This function is like sys.std.Bag.union but that for each pair of argument elements being unioned, the output count value is the sum of the input count values rather than being the maximum of the inputs.
sys.std.Bag.intersection
function sys.std.Bag.intersection (Bag <-- $topic : set_of.Bag)
This function is like sys.std.Core.Relation.intersection as union is like sys.std.Core.Relation.union; the minimum of count attribute values is used rather than the maximum.
sys.std.Bag.diff
function sys.std.Bag.diff (Bag <-- $source : Bag, $filter : Bag)
This function is like sys.std.Core.Relation.diff as union is like sys.std.Core.Relation.union; for corresponding input tuples, the result only has a tuple with the same value if the count of the source tuple is greater than the count of the filter tuple, and the count of the result tuple is the difference of those two.
SEE ALSO
Go to Muldis::D for the majority of distribution-internal references, and Muldis::D::SeeAlso for the majority of distribution-external references.
AUTHOR
Darren Duncan (perl@DarrenDuncan.net)
LICENSE AND COPYRIGHT
This file is part of the formal specification of the Muldis D language.
Muldis D is Copyright © 2002-2009, Muldis Data Systems, Inc.
See the LICENSE AND COPYRIGHT of Muldis::D for details.
TRADEMARK POLICY
The TRADEMARK POLICY in Muldis::D applies to this file too.
ACKNOWLEDGEMENTS
The ACKNOWLEDGEMENTS in Muldis::D apply to this file too.