Comment by mistrial9

Pascal interfaces and direct 68k ASM for the first years of Macintosh. C language bindings were third party and discouraged by Apple. There were good reasons for that in those days IMHO, since C came with a lot of Unix software libraries and people would demand that the science libs run. Apple said "no" but third parties built the compilers anyway. Many developers were attracted to Michael Kahl's brilliant ThinkC system, later to MetroWerks. MPW built a more *nix-like environment eventually, also.

source: C language developers for the Macintosh OS