Britney - A simple untyped Lambda Calculus interpreter

See the file "LICENSE" for copyright information and the
terms and conditions for copying, distribution and
modification of Britney.


Compiling Britney from the source package can be done
simply by running 'ant' in the base directory. SableCC
generated files are already present, so no need for
SableCC on your machine.


It is recommended to run Britney from the precompiled
executable jar. A wrapper shell script can be found
in 'bin' (make sure to set the absolute path to the
jar file and make the script executable):

$ path-to-britney/bin/britney


Add the Britney 'bin' directory to your PATH or create
a link to 'bin/britney' from a directory already in
your PATH for easy access to Britney.


To use the definition files 'prelude' and 'hanoi':

$ britney prelude.britney hanoi.britney


To view general or licensing information:

$ britney -info
or
$ britney -license


Available commands and a short description:

use
  Enter a lambda term to use as the current term.
  All actions will always be applied to the current term.

store
  Enter a name to store the current term.
  A possible term stored with the same name will be lost.

print
  Pretty-print the current term.

structure
  Pretty-print the current term with all parentheses.

tree
  Print the abstract syntax tree for the current term.

reduce
  Try to apply one Beta-reduction step to the current term.
  The resulting term will be the new current term.

normalize
  Apply Beta-reduction steps as long as possible.
  Maximum number of reductions is " MAX_TRIES_NORMALIZE .
  The resulting term will be the new current term.

stored
  List all names of stored terms.

match
  The current term will be matched to all stored terms modulo
  Alpha-conversion.

-- [comment]
  Anything on the line will be ignored.
  Usefull to include comments in definition files.

exit
  Exit Britney.

info
  Print some information on Britney (version, credits, etc).

All command line arguments, if present, will be interpreted as
file names for definition files. All commands in these files
will be executed on startup.

Example usage:

  > use
  Term: \x.x
  Current term: \x.x
  > store
  Name: I
  > use
  Term: (\y.y y) I
  Current term: (\y.y y) \x.x
  > normalize
  Number of reductions: 2
  Current term: \x.x