Errett Bishop (1928–1983) was responsible for reviving interest in constructive mathematics as a branch of mathematics. Before this, he had a career in areas of classical (i.e., non-constructive) analysis, including approximation theory?, several complex variables, function algebras, and other fields.
See Bishop's constructive mathematics for a detailed discussion of the system he developed. Bishop's important works in constructive mathematics include:
Foundations of Constructive Analysis (1967), the work which made him famous in the foundations of mathematics circles;
“Schizophrenia in contemporary mathematics” (1973), a philosophical attack on nonconstructive mathematics;
see also: “The crisis in contemporary mathematics”, Historia Mathematica Volume 2, Issue 4, November 1975, Pages 507-517 (doi.org/10.1016/0315-0860(75)90113-590113-5))
Constructive Measure Theory (1972, with Henry Cheng?), featuring a better measure theory than in FCA;
Constructive Analysis (1985, with Douglas Bridges), a revised version of FCA, incorporating the measure theory of CMT.