Besides keys, each data type in Pop-11 has a collection of associated procedures, some for constructing new instances of that type (e.g. consstring, consvector, consword, conspair) some for accessing or updating components of structures (e.g. subscrs, subscrv, subscrw, front, back), and some for recognizing instances (e.g. isstring, isvector, isword, ispair).
There are also some "generic" procedures that are applicable to a wide range of data-structures, including the following:
o the equality and identity test procedures "=" and "==",
o pr, the maihn printing procedure
o explode which puts all components of a structure onto the Pop-11
stack,
o datalist, which makes a list of components,
o length and datalength which return the number of fields in
a structure.
o appdata which applies a procedure to all the components,
o mapdata which takes a structure and a mapping procedure and
produces a copy of the structure with the components mapped
o copy, which copies a structure at top level, occasionally with
results that surprise users, e.g. when applied to pairs.
o copydata, which copies recursively
o fill, which transfers items from the stack into the fields of
a datastructure.
o datakey, which returns the key associated with an object's type
o dataword, which returns the word that names the object's type
o allbutfirst, a procedure for creating a copy of a list or other
structure minus the first N elements.
o allbutlast, a procedure for creating a copy of a list or other
structure minus the last N elements.
o <> the concatenator procedure <>, which can join or "compose"
lists, strings, words, vectors or even two procedures, to form
a new more complex object of the same type as its inputs.
o >< the "string concatenator" which takes any two printable objects
and produces a string which combines their printing forms.
A generic feature of records, vector type objects and lists in Pop-11 is
that if an object O of one of these types is applied to a positive
integer N that is smaller than the length of O, then O is treated as if
it were a function and the result of O(N) is the Nth component of O.
Similarly the form can be used to update the N'th component, as in:
-> O(N);The behaviour of a structure applied to an object can be re-defined for user data types using the class_apply facility, to specify how an object should behave if treated as a procedure. (See HELP CLASSES, REF KEYS)
Other generic facilities are defined in the following online Poplog documentation files:
REF DATA, REF DEFSTRUCT, REF RECORDS, REF VECTORS, REF KEYS
Yet more generic procedures can be defined by the user via the Objectclass library described briefly in Chapter 8, below.
The file REF NUMBERS describes generic mathematical operations that can be applied to all types of numbers represented in Poplog, integers, bigintegers, rationals, decimals, ddecimals and various kinds of complex numbers. E.g. "+", "-", "*", "/", and "sqrt" are generic in this sense.