[Haskell-cafe] Writing tool question (may be out of scope here)

[Saul Malesac]

Hi,

Excuse me if that is out of subject here, but does anyone know which
tool/writing framework was used to write the "Real world Haskell" book
?
I'm wondering, in particular, about the capability to
write/edit/publish it online while allowing people to leave comments,
then have a paperback/PDF version.

Thanks in advance,

-- 
Saul