The Free On-line Dictionary of Computing (30 December 2018):

Tree Transformation Language
TXL

    (TXL) A hybrid functional language and
   rule-based language developed by J.R. Cordy
    et al of Queen's University, Canada in
   1988.  TXL is suitable for performing source to source analysis
   and transformation and for rapid prototyping of new languages
   and language processors.  It uses structural transformation
   based on term rewriting.

   TXL has been particularly successful in software engineering
   tasks such as design recovery, refactoring, and
   reengineering.  Most recently it has been applied to
   artificial intelligence tasks such as recognition of
   hand-written mathematics, and to transformation of structured
   documents in XML.

   TXL takes as input an arbitrary context-free grammar in
   extended BNF-like notation, and a set of show-by-example
   transformation rules to be applied to inputs parsed using
   the grammar.  TXL supports the notion of agile parsing, the
   ability to tailor the grammar to each particular task using
   "grammar overrides".

   TXL Home (http://txl.ca/).

   ["TXL: A Rapid Prototyping System for Programming Language
   Dialects", J.R. Cordy, C.D.; Halpern and D. Promislow,
   Computer Languages, Vol. 16, No. 1, January 1991, pp 97-107]

   ["Source Transformation in Software Engineering using the TXL
   Transformation System", J.R. Cordy, T.R. Dean, A.J. Malton and
   K.A. Schneider, Journal of Information and Software
   Technology, Vol. 44, No. 13, October 2002, pp 827-837]

   ["Recognizing Mathematical Expressions Using Tree
   Transformation", R. Zanibbi, D. Blostein and J.R. Cordy, IEEE
   Transactions on Pattern Analysis & Machine Intelligence,
   Vol. 24, No. 11, November 2002, pp 1455-1467]

   ["Agile Parsing in TXL", T.R. Dean, J.R. Cordy, A.J. Malton
   and K.A. Schneider, Journal of Automated Software Engineering,
   Vol. 10, No. 4, October 2003, pp 311-336]

   (2003-11-04)