[r6rs-discuss] ANN: Larceny v0.95 "First Safety"
William D Clinger
will at ccs.neu.edu
Thu Nov 8 15:01:02 EST 2007
Larceny v0.95, "First Safety", is now available
for download at http://larceny.ccs.neu.edu/
Larceny v0.95 is the first public release of a
multiplatform implementation that supports all
four de facto standards for Scheme: IEEE/ANSI,
R5RS, ERR5RS, and the R6RS [1,2,3,4]. Larceny
v0.95 is also the first complete implementation
of an R6RS-compatible system.
Larceny makes ERR5RS and R6RS libraries available
to all ERR5RS programs, R6RS top-level programs,
and Scheme scripts. Larceny's ERR5RS mode offers
an interactive read/eval/print loop that allows
programmers to define and to import libraries,
and to load libraries and code from files, while
remaining almost fully compatible with the R5RS
and interoperable with both R5RS and R6RS code.
In Larceny's R6RS-compatible modes, libraries may
be defined within the file that contains the R6RS
top-level program or Scheme script; we urge all
other implementors of the R6RS to support this
vitally important extension of that standard.
Larceny's R6RS-compatible modes are not fully
R6RS-conforming, but most deviations merely
omit one of the punitive portability checks
mandated by the R6RS. These omissions do not
affect the execution of production code, and
do not compromise Larceny's traditional safety.
Some of First Safety's new features are of beta
quality; its evocative version name reminds you
it's not quite fair to condemn a whole program
because of a single slip-up. We will improve
compatibility, performance, and debugging of
ERR5RS and R6RS modes in future releases.
We are grateful to Andre van Tonder for letting
us use his portable implementation of libraries,
syntax-case, and the ERR5RS-compatible top level.
We acknowledge the contributions by Harold Ancell,
David Rush, and other SchemePunks who worked on
the design of ERR5RS. We appreciate Microsoft's
support for projects that will use Common Larceny
William D Clinger
Felix S. Klock II
 IEEE Standard for the Scheme Programming
Language. IEEE Std 1178-1990.
 Richard Kelsey, William Clinger, and Jonathan
Rees [editors]. Revised^5 Report on the Algorithmic
Language Scheme. Higher-Order and Symbolic
Computation, Volume 11, Issue 1, August 1998, pages
7-105. Online at
 In the v0.95 release, native Larceny and Petit
Larceny support ERR5RS, R6RS, and Snow but Common
Larceny does not. Future releases of Common Larceny
are likely to support ERR5RS and the R6RS but not
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