From The Free On-line Dictionary of Computing (19 January 2023):
Bird-Meertens Formalism BMF Squiggol
<theory, programming> (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)