git clone 'https://github.com/dsorokin/trivial-lazy.git'
TRIVIAL-LAZY – Trivial lazy macros and functions for Common Lisp
It was implemented many times and by many people. It has turned out that I needed a separate and complete library that would implement trivial lazy macros and functions DELAY, FORCE and MEMO described in SICP. Only my implementation has an optional support of multi-threading.