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

Bird-Meertens Formalism
BMF
Squiggol

    (BMF) (Or "Squiggol") A calculus for
   derivation of functional programs from a specification.  It
   consists of a set of higher-order functions that operate on
   lists including map, fold, scan, filter, inits, tails,
   cross product and function composition.

   ["A Calculus of Functions for Program Derivation", R.S. Bird,
   in Res Topics in Fnl Prog, D. Turner ed, A-W 1990].

   ["The Squiggolist", ed Johan Jeuring, published irregularly by
   CWI Amsterdam].

   (1995-05-01)