In the 1960s, Meertens applied affix grammars to the description and composition of music, and obtained a special prize from the jury at the 1968 IFIP Congress in Edinburgh for his computer-generated string quartet, "Quartet No. 1 in C Major for 2 Violins, Viola and Violoncello" based on the first non-context-free affix grammar. The string quartet was published as Mathematical Centre Report MR 96 in 1968.
Meertens was one of the editors of the Revised ALGOL 68 Report. He was the originator and one of the designers of the ABC programming language. He was chairman of the Dutch Pacifist Socialist Party (PSP) from 1975 until 1981. He was co-designer of the Bird–Meertens formalism. He was chair of IFIP Working Group 2.1 on Algorithmic Languages and Calculi from 1999 to 2009.
His original work was at the Centrum Wiskunde & Informatica (CWI) in Amsterdam, The Netherlands (originally called the Mathematical Centre). He was later researcher at the Kestrel Institute in Palo Alto, United States. He is Professor Emeritus at Utrecht University, Utrecht, The Netherlands.
The Meertens number is named after him.
- Prof.dr. L.G.L.Th. Meertens (1944 - ) at the Catalogus Professorum Academiæ Rheno-Traiectinæ
- Cordula Rooijendijk. Alles moest nog worden uitgevonden. Atlas, 2007. (In Dutch).
- Kassler, Michael (1969), "Report from Edinburgh", Perspectives of New Music, Perspectives of New Music, Vol. 7, No. 2, 7 (2), pp. 175–177, JSTOR 832302, doi:10.2307/832302.
- Quartet no. 1 in c major for 2 violins, viola and violoncello. Score and links to mp3 sound files of a performance by the Amsterdam String Quartet (1968).