An ascii Christmas tree turing tarpit language.
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Cameron Swords
Rebecca Swords

Load "tannenbaum.scm" and call (run [filename]).
This was all written in Petite Chez Scheme 8.4, but I do
not have any reason to believe any R6RS-compatible
Scheme implementation won't run it.

The syntax of this language is described in the top of
the main file, but is reproduced here:

$ -> (lexical-var 0)
$ $ -> (lexical-var 1)
( -> lambda
) -> close lambda
@ -> application
% -> spacing
0 -> 'this line'
* -> start program
| -> end program
+ -> line reference to line 1
+ + -> line reference to line 2

Any program starts with a * (every Christmas tree has a
star on top) and ends with a | (every tree has a trunk).

Each line is a single lambda expression, and the code in
parens makes up the body of that lambda (and each lambda
is implicity single-argument); multiple arguments are
'possible' through currying in the usual fashion.

Any argument may be looked up in the environment using a
number of $s equivalent to its lexical address.

Functions may be called using a number of +s equal to
their line number, or a 0 to reference the lambda whose
body your are currently in (so 0 provides recursive
abilities). Functions may also be passed in this way.

The two examples included are omega.tbm, which contains
((lambda (x) (x x)) (lambda (x) (x x))), and ski.tbm, in
which line 1 is the I combinator, line 2-3 are the K
combinator, and lines 4-7 are the S combinator.

The very last line of any input is itself a lambda, but
its body is run as the 'main', so asking for arguments
in it may not be wise.

Since this language is provides the entire lambda
calculus, it is necessarily Turing complete. However,
good luck doing anything other than making pretty trees
with it.