Burke_et_al-NIL_Reference_Manual_0286-1984

Random Internal Types 8 NIL Manual
2.8 Random Internal Types
Here are some of the internal1y used types in NIL . While they should generally not be seen,
they may pop up on occasion either themselves or as a result of errors.
2.8.1 l\1inisubrs
lbe minisubr type is somewhat gratuitous: it win be flushed as a separate type someday. and
its type bits reused by something more uscthl. A millisubr is a special rOlltine within the 1'11.
k~rnel: Stich routines arc caned with the VAX JSB instn.ctioll. However. they tend to have
various assuned
2.8.2 Modules
A module. as a type. is the structure used by Nil. to contain a collection of compiled
functions and the constants and jat~lstructures they ·reference. When the cumpiler compiles a file.
it produces a module. When the garbagecollcctor (haha) relocates things. it rehlC,ttcs the module
as a hlnck. The use of the name module for this primilhe dalHstnlcture is it bit pretentious .. so it
will probably be called something like compiled-code-modufe in the future.
2.8.3 Internal Markers
The type si:internal-marker is used for variolls things in 1Ioi1L. none of which should
ordinarily be visible to (or touched by) the user. Objects of this type are meant to be checked
for by things like the debugger and garbage-collector (to. for instance. parse stack frames). and
manipulating them out of context wiUconfusc tllese programs.
These objects print out as #!
#fAFM-31
#fPC"MARKI
#!DOUBLE-FLOAT-MARK!
#!NULL-ARGI
followed by the name followed by!. For instance,
; Stack marker for 3-arg function
; call frame
; Next slot on stack is a PC
: Next two stack entries are the
; representation of a double-float
; Stack slot is for an argument which
has not yet been computed,in a
: function caU frame.
MC:Nll.MAN:TYPES 36