Some very interesting code. They are extremely short, yet extremely powerful.

* cps.ss - a CPS transformer

* meta-interp.ss - a meta-circular interpreter (reflection tower)

* infer.ss - a type inferencer for the lambda calculus. It can infer
  infinite types (such as delta, omega, and the Y-combinator)

* bottom-up-typing.ss - a bottom-up type inference algorithm for
  Hindley-Milner system

* mk-c.ss - a modified miniKanren implementation with a negation
  operator

* interp-call-by-need.ss - a lazy interpreter

* lazy-ski.ss - a compiler from lambda calculus to "lazy combinators"

* interp-delim.ss - a simple interpreter with delimited continuation
  operators (shift/reset/shift0/reset0)

* encoding.scm - encodings of various things in the lambda calculus

* pmatch.scm - supporting macro for pattern matching