About Symbols

This note is called: [SYMBOLS]
The notations used in this note is described in [NOTATION]
Under development

The [data-type] [symbol] is usually found in non-LISP like programming language (Ruby has a type called Symbol but its behavior and rational are different the LISP-like symbols). [symbol]s are useful because they have PARTS that are immutable (like their 'name') and parts that are mutable (like 'value' and 'plist'). [symbl]s are created from [string]s using the operator 'intern'. In its simplest form 'intern' takes a [string] and returns a [symbol].

  (intern [string]) ==> [symbol]                                 constructor

Unlike many constructors of things with mutable parts 'inter is functional. That is

  (implies (equal s1 s2) (equal (inter s1) (intern s2))

Aside
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The [plist} ( < [alsit]) of a [symbol] may have different [representation]s

The usual [representation] foe [plist]s used by IBUKI it the default
[representation] for [alist]s 

  [plist] == |Empty-List|  OR
             ( (,[attribute] . ,[value]) . ,[plist])


but in Allegro lisp

  [plist] == |Empty-List|  OR
             ( ,[attribute] ,[value] . ,[plist])


that is, a list of even length where [attributes are just followed by its
value. This representation saves both some space and time.
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The existence of both immutable and mutable attributes of [symbol]s is their secret sause.