TeX is written in the programming language WEB; WEB
is a tool to implement the concept of “literate programming”.
Knuth's original implementation will be in any respectable
distribution of TeX, but the sources of the two tools
weave), together with a manual
outlining the programming techniques, may be had from CTAN.
CWEB, by Silvio Levy, is a WEB for C programs.
FWEB, by John Krommes, is a version for Fortran,
Ratfor,C, C++, working with LaTeX; it was derived
Spidery WEB, by Norman Ramsey, supports many
languages including Ada,
awk, and C
and, while not in the public domain, is usable without charge. It is
now superseded by
noweb (also by Norman Ramsay) which
incorporates the lessons learned in implementing spidery WEB,
and which is a simpler, equally powerful, tool.
SchemeWEB, by John Ramsdell, is a Unix filter that
translates SchemeWEB into LaTeX source or Scheme source.
APLWEB is a version of WEB for APL.
FunnelWeb is a version of WEB that is language independent.
Other language independent versions of WEB are
is written in ANSI C).
Tweb is a WEB for Plain TeX macro files, using