===== Conversion rules =====

==== nul to:====

  * ATOM
    * ‘’
  * INTEGER
    * 0
  * FLOAT
    * 0.0
  * VECTOR
    * | 0.0 0.0 0.0 0.0 |
  * REFERENCE
    * ‘’#0 (nul)
  * INSTANCE
    * nul
  * list
    * {}
  * function parameter
    * default value

==== ATOM to: ====

  * INTEGER
    * ‘’ converts to 0
    * all other values convert to 1
  * FLOAT
    * ‘’ converts to 0.0
    * all other values convert to 1.0
  * VECTOR
    * ‘’ converts to | 0.0 0.0 0.0 0.0 |
    * all other values convert to | 1.0 1.0 1.0 1.0 |
  * REFERENCE
    * ‘’ converts to nul
    * all other values convert to <atom>#0. If <atom>#0 does not exist, it is created.
  * INSTANCE
    * converts to nul
  * list
    * converts to a single item list.
    * type of the list defines the conversion rule for the single item.
  * ARRAY
    * converts to a single item array
    * item[1] contains the pointer to the input token

==== INTEGER to: ====

  * FLOAT
    * common conversion
  * VECTOR
    * converts to | value value value value |
  * ATOM
    * 0 converts to ‘’
    * all other values convert to ‘true’
  * REFERENCE
    * converts to nul
  * INSTANCE
    * converts to nul
  * list
    * converts to a single item list.
    * type of the list defines the conversion rule for the single item.
  * ARRAY
    * converts to a single item array
    * item[1] contains the pointer to the input token

==== FLOAT to:====

  * INTEGER
    * common conversion
  * VECTOR
    * converts to | value value value value |
  * ATOM
    * 0.0 converts to ‘’
    * all other values convert to ‘true’
  * REFERENCE
    * converts to nul
  * INSTANCE
    * converts to nul
  * list
    * converts to a single item list.
    * type of the list defines the conversion rule for the single item.
  * ARRAY
    * converts to a single item array
    * item[1] contains the pointer to the input token

==== VECTOR to:====

  * INTEGER
    * x component is used
  * FLOAT
    * x component is used
  * ATOM
    * x component 0.0 converts to ‘’
    * all other values for x component convert to ‘true’
  * REFERENCE
    * converts to nul
  * INSTANCE
    * converts to nul
  * list
    * converts to a single item list.
    * type of the list defines the conversion rule for the single item.
  * ARRAY
    * converts to a single item array
    * item[1] contains the pointer to the input token

==== REFERENCE to:====

  * INTEGER
    * nul converts to 0
    * all valid references convert to 1
  * FLOAT
    * nul converts to 0.0
    * all valid references convert to 1.0
  * VECTOR
    * nul converts to | 0.0 0.0 0.0 0.0 |
    * all valid references convert to | 1.0 1.0 1.0 1.0 |
  * ATOM
    * converts to template name of the OBJECT
  * INSTANCE
    * converts to nul (todo: converts to owned engine object)
  * list
    * converts to a single item list.
    * type of the list defines the conversion rule for the single item.
  * ARRAY
    * converts to a single item array item[1]
    * contains the pointer to the input token

==== INSTANCE to:====

  * INTEGER
    * nul converts to 0
    * all valid references convert to 1
  * FLOAT
    * nul converts to 0.0
    * all valid references convert to 1.0
  * VECTOR
    * nul converts to | 0.0 0.0 0.0 0.0 |
    * all valid references convert to | 1.0 1.0 1.0 1.0 |
  * ATOM
    * converts to nul (todo: INSTANCE name)
  * REFERENCE
    * converts to nul (todo: converts to owner database object)
  * list
    * converts to a single item list.
    * type of the list defines the conversion rule for the single item.
  * ARRAY
    * converts to a single item array item[1]
    * contains the pointer to the input token   

==== list to:====

  * single token data type
    * empty list converts to nul
    * otherwise, list[1] is converted
  * different type of list
    * a new list is generated and each item is converted
  * ARRAY
    * an array of pointers to each item in the list is generated

==== ARRAY to:====
  * single token data type
    * empty list converts to nul
    * otherwise, list[1] is converted
  * list
    * a new list is generated and each item is converted.