This is a lambda calculus parser and evaluator written in F#.
It is actually pretty much the same parser and evaluator twice: once as a set of modules with Lambda.fs as the entry point, and once as a script file (Lambda.fsx)
You can build the project using the build script.
On Windows, do roughly this:
.paket/paket.exe install
build.cmd
build/Lambda.exe
On Mac OS X and maybe Linux, do roughly this:
mono .paket/paket.exe install
./build.sh
mono build/Lambda.exe
Now you can type lambda expressions into the REPL, say:
(λn.λf.λx.f (n f x)) (λf.λx.x)
Which should give you this back:
λf.λx.f x