Module pl.Set

A Set class.

> Set = require 'pl.Set'
> = Set{'one','two'} == Set{'two','one'}
true
> fruit = Set{'apple','banana','orange'}
> = fruit['banana']
true
> = fruit['hazelnut']
nil
> colours = Set{'red','orange','green','blue'}
> = fruit,colours
[apple,orange,banana]   [blue,green,orange,red]
> = fruit+colours
[blue,green,apple,red,orange,banana]
[orange]
> more_fruits = fruit + 'apricot'
> = fruit*colours
=  more_fruits, fruit
banana,apricot,apple,orange]    [banana,apple,orange]

Dependencies: pl.utils, pl.tablex, pl.class, pl.Map, (pl.List if __tostring is used)

Functions

 Set (t) create a set. values (self) get a list of the values in a set. map (self, fn, ...) map a function over the values of a set. union (self, set) union of two sets (also +). intersection (self, set) intersection of two sets (also *). difference (self, set) new set with elements in the set that are not in the other (also -). issubset (self, set) is the first set a subset of the second (also <)?. isempty (self) is the set empty?. isdisjoint (s1, s2) are the sets disjoint? len (s) size of this set (also # for 5.2).

metamethods

 __tostring () string representation of a set. __add () union of sets. __mul () intersection of sets. __sub () difference of sets. __pow () symmetric difference of sets. __lt () first set subset of second? __len () cardinality of set (5.2). __eq (s1, s2) equality between sets.

Functions

Set (t)
create a set.

Parameters:

• t may be a Set, Map or list-like table.
values (self)
get a list of the values in a set.

• self a Set

Returns:

a list
map (self, fn, ...)
map a function over the values of a set.

Parameters:

• self a Set
• fn a function
• ... extra arguments to pass to the function.

Returns:

a new set
union (self, set)
union of two sets (also +).

Parameters:

• self a Set
• set another set

Returns:

a new set
intersection (self, set)
intersection of two sets (also *).

Parameters:

• self a Set
• set another set

a new set

Usage:

> s = Set{10,20,30}
> t = Set{20,30,40}
> = t
[20,30,40]
> = Set.intersection(s,t)
[30,20]
> = s*t
[30,20]
difference (self, set)
new set with elements in the set that are not in the other (also -).

Parameters:

• self a Set
• set another set

Returns:

a new set
issubset (self, set)
is the first set a subset of the second (also <)?.

Parameters:

• self a Set
• set another set

Returns:

true or false
isempty (self)
is the set empty?.

• self a Set

Returns:

true or false
isdisjoint (s1, s2)
are the sets disjoint? (no elements in common). Uses naive definition, i.e. that intersection is empty

Parameters:

• s1 a Set
• s2 another set

Returns:

true or false
len (s)
size of this set (also # for 5.2).

• s a Set

size

metamethods

__tostring ()
string representation of a set.
union of sets.
__mul ()
intersection of sets.
__sub ()
difference of sets.
__pow ()
symmetric difference of sets.
__lt ()
first set subset of second?
__len ()
cardinality of set (5.2).
__eq (s1, s2)
equality between sets.

Parameters:

• s1
• s2
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