Warning: this is an htmlized version!
The original is here, and
the conversion rules are here. 
-- This file:
--   http://anggtwu.net/LEAN/README.html
--   http://anggtwu.net/LEAN/README
--          (find-angg "LEAN/README")
-- Author: Eduardo Ochs <eduardoochs@gmail.com>

The file

  http://anggtwu.net/LEAN/fplean4.pdf

is a conversion to PDF of this book, by David Thrane Christiansen:

  https://leanprover.github.io/functional_programming_in_lean/
  https://leanprover.github.io/functional_programming_in_lean/print.html