This directory contains a few example Racket extensions. Most
examples are implemented directly in C. A few examples listed at the
end use the mzc `c-lambda', etc. forms.
* hello.c - returns the string "Hello, World!". Demonstrates creating
a Scheme value.
* fmod.c - defines the `fmod' procedure, which calculates modulo on
floating-point numbers. Demonstrates creating Scheme procedures
from C and adding top-level definitions. (Manually instrumented for
3m, so do not use `mzc --xform'.)
* curses.c - links Racket to the curses library. Demonstrates more
procedures and definitions, a little more type dispatching, and
returning multiple values. (Manually instrumented for 3m, so do not
use `mzc --xform'.)
* makeadder.c - defines `make-adder', which takes a number and
returns a procedure that takes another number to add to
it. Demonstrates closure creation in C, getting Scheme global
values, and calling Scheme procedures from C.
makeadder3m.c - the same, but manually instrumented 3m (so do not
use `mzc --xform'). Making the code work with 3m requires several
changes, but `mzc --xform' works on "makeadder.c" without changes.
* catch.c - defined `eval-string/catch-error', which catches
exceptions while evaluating a string. Demonstrates how to catch
exceptions from C code.
* bitmatrix.c - implements two-dimensional bit matrixes with some
operations. Demonstrates defining a new Scheme data type, data
allocation, fancy integer type checking, general exception raising,
and registering static variables. Also demonstrates supplying
traversal functions for 3m (but still needs `mzc --xform'
preprocessing to build for 3m).
* idmodule.c - Declares the module named `idmodule' that provides an
`identity' function. Demonstrates implementing a primitive module
in C.
* helloprint.c - prints "Hello, World!" directly to the current
output port rather than relying on the read-eval-print-loop.
Demonstrates using built-in Scheme parameter values from C.
* tree.cxx, tree-finish.ss - shows how to inject a C++ class into
MzLib's class.ss world. (Does not work with 3m.)
* fmod-ez.ss - same as fmod.c, but with 10% of the code. Demonstrates
`c-lambda'.
* cfile.ss - simple (and unsafe) glue to the fopen(), fread(),
fwrite(), and fclose() C library functions. Demonstrates the use of
`(pointer ...)' types. Technically, this example is broken for 3m,
because fclose() frees the FILE* pointer, and it's possible that
the GC will later try to use the same memory.
* msgbox.ss - a Windows-only example, provides a `message-box'
procedure. Demonstrates some of the limitations of `c-lambda' and
how to work around them.
