SBCL TODO ========= "There's nothing an agnostic can't do as long as he doesn't know whether he believes in anything or not." -- Monty Python. "God grant me serenity to accept the code I cannot change, courage to change the code I can, and wisdom to know the difference." -- Erik Naggum "Accumulation of half-understood design decisions eventually chokes a program as a water weed chokes a canal. By refactoring you can ensure that your full understanding of how the program should be designed is always reflected in the program. As a water weed quickly spreads its tendrils, partially understood design decisions quickly spread their effects throughout your program. No one or two or even ten individual actions will be enough to eradicate the problem." -- Martin Fowler, in _Refactoring: Improving the Design of Existing Code_, p. 360 "I wish I didn't know now what I didn't know then." -- Bob Seger This files is maintained as part of the SBCL distribution, and describes flying pies and moons on sticks that SBCL developers dream about. The items are in no particular order. The omission of an item is no guarantee that no-one would like it, just like the inclusion of an item is no guarantee that someone is actively working on it. In addition to this file, there is the BUGS file, and there are also hundreds of FIXME notes in the sources. (Things marked as KLUDGE are in general things which are ugly or confusing, but that, for whatever reason, may stay that way indefinitely.) THREADING INTERFACE SB-THREAD has some problems: recursivity of a mutex should probably be a feature of the mutex, and not of the lexical location. Thread local variables are needed. Sessions and sharing the terminal need to be thought about. PEEPHOLE OPTIMIZER Have you ever read SBCL disassembly? DEFGLOBAL Global lexical variables. Esp. since with threads special variable accesses is no speed daemon. FINISHING EXTERNAL FORMATS Byte order marks. Newline conventions. A way to specify an external format without needing to duplicate code. Fixing the inefficiencies. TIMEOUTS Asyncronous unwinds suck horribly, but to implement reliable systems one simply needs timeouts. These should probably be local, since otherwise they effectively become asynchronous unwinds. Basically, for any potentially blocking operation there should be a :TIMEOUT arguent (or a version of the operation that accepts the argument). ADVICE/FWRAP SBCL has an internal function encapsulation mechanism, and is able to install breakpoint to function start/end -- this is used to implement the instrumentation based profiler and tracing. It would be good to have this as an exported interface, and it would be good if the SYMBOL-FUNCTION / FDEFINITION confusion was fixed: currently the latter returns the underlying definition, whereas the first returns the encapsulation. GENERIC FUNCTION TRACING This sucks currently. It would also be good to be able to trace individual methods. POLICY MADNESS The interactions between various optimization policies are far from obvious. Someone should figure out how to make this better, and fix it. One option would be to have just a few (eg. DEBUG, SMALL, FAST-SAFE, FAST-UNSAFE) "dominant" policies, and expose the rest as separately declarable optimization toggles. MAYBE-INLINE is also nice, but it would be good if someone could figure out how to get rid of it while retaining the semantics it provides. Inlining recursive functions is also something to think about. INHIBIT-WARNINGS really needs to go away. WINDOWS Needs love. DARWIN Needs love, particularly threads and exceptions/signals. slam.sh is also broken there. FUNCTION NAMES We'd like to be able to (SETF %FUNCTION-NAME) on a closure. UNDEFINED FUNCTION / VARIABLE RESTARTS You know, like Allegro is reputed to have. MISC CLEANUPS These need to be taken a good look at -- it might be that some of them are already done, or otherwise no longer relevant.) * EVAL/EVAL-WHEN/%COMPILE/DEFUN/DEFSTRUCT cleanups: ** make %COMPILE understand magicality of DEFUN FOO w.r.t. e.g. preexisting inlineness of FOO ** use %COMPILE where COMPILE-TOP-LEVEL used to be used ** remove redundant COMPILE-TOP-LEVEL and FUNCTIONAL-KIND=:TOP-LEVEL stuff from the compiler * outstanding embarrassments ** :IGNORE-ERRORS-P cruft in stems-and-flags.lisp-expr. (It's reasonable to support this as a crutch when initially bootstrapping from balky xc hosts with their own idiosyncratic ideas of what merits FAILURE-P, but it's embarrassing to have to use it when bootstrapping under SBCL!), * miscellaneous simple refactoring * belated renaming: ** rename %PRIMITIVE to %VOP ** A few hundred things named FN should be named FUN * These days ANSI C has inline functions, so.. ** redo many cpp macros as inline functions: HeaderValue, Pointerp, CEILING, ALIGNED_SIZE, GET_FREE_POINTER, SET_FREE_POINTER, GET_GC_TRIGGER, SET_GC_TRIGGER, GetBSP, SetBSP, os_trunc_foo(), os_round_up_foo() ** remove various avoid-evaluating-C-macro-arg-twice cruft * Some work on conditions emitted by the system ** eliminate COMPILER-WARN and COMPILER-STYLE-WARN, which were simply limited versions of WARN and STYLE-WARN. ** eliminate use of INHIBIT-WARNINGS by code emitted by the system from user code. ** cause use of INHIBIT-WARNINGS to signal a STYLE-WARNING. ** eliminate use of INHIBIT-WARNINGS within the system ** deprecate INHIBIT-WARNINGS, causing its use to signal a full WARNING. ** begin work on developing a class hierarchy of conditions along semantic lines. PCL INTEGRATION AKA CLOS in cold init. HIGH LEVEL SOCKET INTERFACE Something slightly above the level of BSD sockets would be nice. RPC INTERFACE For talking with other processes. CROSS PLATFORM GUI Since this is a high priority we're waiting for PHP coders to offer their help to build a website about this. BLOCK COMPILATION You know, like CMUCL does. (MOSTLY) PARALLEL GC Several algorithms exist, even one would be nice. INCREMENTAL GC For those who need it.