Prehistory
----------

We designed the Mercury execution algorithm in October 1993. We started
working on a Mercury compiler in December 1993. Semantic analysis
started working around May 1994. We started generating code around
August 1994; we started work on optimizations very soon after. The
compiler successfully compiled itself on 24 February 1995.


Mercury 0.1, April 8 1995
-------------------------
Initial beta-test release. 
Very resource-hungry, not very well documented.


Mercury 0.2, April 18 1995
--------------------------
Much better error messages for determinism errors, much
faster compilation, much lower memory requirements for bootstrapping.
The C compilation is much faster and requires much less memory since we
now by default compile to one C function per procedure, but we also
improved the speed of the Mercury compiler itself by nearly 40% by
implementing some library predicates much more efficiently.


Mercury 0.2.5, 1 June 1995
--------------------------
Much better syntax error messages.
Better documentation, now including a library reference manual.
Added a GNU autoconf configuration script.
Ported to IRIX 5.
Added `multidet'.  
Enabled the use of tag bits in combination with conservative garbage
collection (this improved the speed of the compiler by about 20%).
Compile directly to C rather than via the old .mod files, which were
post-processed by a Perl script (improves compilation speed, reduces
disk space requirements, removes dependency on Perl).
Lots of bug fixes.


Mercury 0.3, 18 July 1995
-------------------------
The first public release.
Better type error messages.
Better determinism error messages.
Only recompiles <module>_init.c after `mmake depend', rather than after
anything changes.
Ported to ULTRIX (N.B. - ULTRIX's /bin/sh sucks).
Avoid saving variables on the stack before negated contexts.
Don't embed label names as strings in the executable.
A few other efficiency improvements.
Lots of bug fixes.
Made the rule for `mmake clean' less reckless (don't do `rm -f *.c').
Rationalized the options to `mc'.  Implemented a couple of new ones.
Added a symbol demangler to improve linker error messages.
Made very significant improvements to the documentation.
Added a "Prolog to Mercury transition guide".
