CHICKEN Scheme’s included
Symbol property lists are a long-standing Lisp feature
(see History of LISP)
which attaches a empty list to each (exisiting or defined) symbol.
This list is similar to an associative array, in that data can be stored in conjunction with a naming property;
Clojure’s metadata functionality is related in concept.
Practically, this allows to attach named (meta-)data to unique identifiers.
CHICKEN, property lists are provided via the included
(chicken plist) module.
Internally, these property lists are realized, not as a list of pairs,
but a list alternating between property and value for all property-value pairs.
The two central functions from this module are:
(put! sym prop val)- Returns value argument, which is added a under property argument to the property list of argument symbol.
(get sym prop)- Returns value of property argument in property list of symbol argument, or false if symbol or property does not exist.
matrico, property lists are used to emulate Docstrings.
This is achieved by using the
define* macro from the
which assigns a string to a symbol (
put!) with the name of the binding used in the associated
matrico function is provided to retrieve the docstring (
get) for a given function name passed as a symbol and display it.
Next, in a multi-part series, the user-facing functions of
matrico are detailed.