Implement :main (see ticket #662) Patch from Volker Stolz, minor mods by me When matching commands, we now look for (a) an exact match, and (b) the first prefix match we find in the list. This is so that :module can still be abbreviated by :m, to avoid surprise. Docs still to do.
Improve the GC behaviour of IORefs (see Ticket #650). This is a small change to the way IORefs interact with the GC, which should improve GC performance for programs with plenty of IORefs. Previously we had a single closure type for mutable variables, MUT_VAR. Mutable variables were *always* on the mutable list in older generations, and always traversed on every GC. Now, we have two closure types: MUT_VAR_CLEAN and MUT_VAR_DIRTY. The latter is on the mutable list, but the former is not. (NB. this differs from MUT_ARR_PTRS_CLEAN and MUT_ARR_PTRS_DIRTY, both of which are on the mutable list). writeMutVar# now implements a write barrier, by calling dirty_MUT_VAR() in the runtime, that does the necessary modification of MUT_VAR_CLEAN into MUT_VAR_DIRY, and adding to the mutable list if necessary. This results in some pretty dramatic speedups for GHC itself. I've just measureed a 30% overall speedup compiling a 31-module program (anna) with the default heap settings :-D
Improve the GC behaviour of IOArrays/STArrays See Ticket #650 This is a small change to the way mutable arrays interact with the GC, that can have a dramatic effect on performance, and make tricks with unsafeThaw/unsafeFreeze redundant. Data.HashTable should be faster now (I haven't measured it yet). We now have two mutable array closure types, MUT_ARR_PTRS_CLEAN and MUT_ARR_PTRS_DIRTY. Both are on the mutable list if the array is in an old generation. writeArray# sets the type to MUT_ARR_PTRS_DIRTY. The garbage collector can set the type to MUT_ARR_PTRS_CLEAN if it finds that no element of the array points into a younger generation (discovering this required a small addition to evacuate(), but rough tests indicate that it doesn't measurably affect performance). NOTE: none of this affects unboxed arrays (IOUArray/STUArray), only boxed arrays (IOArray/STArray). We could go further and extend the DIRTY bit to be per-block rather than for the whole array, but for now this is an easy improvement.
The ./darcs-all script at the top level is an easier way to do darcs pull/push/get on the whole tree (it should probably allow more commands; I'll fix that later). libraries/default-packages is a list of darcs repositories with which to populate the libraries tree.
GHC.runStmt: run the statement in a new thread to insulate the environment from bad things that the user code might do, such as fork a thread to send an exception back at a later time. In order to do this, we had to keep track of which thread the ^C exception should go to in a global variable. Also, bullet-proof the top-level exception handler in GHCi a bit; there was a small window where an exception could get through, so if you lean on ^C for a while then press enter you could cause GHCi to exit.