Here's the code for it https://github.com/coreutils/coreutils/blob/master/src/yes.c https://github.com/coreutils/coreutils/blob/master/src/yes.c The core is a

Here's the code for it https://github.com/coreutils/coreutils/blob/master/src/yes.c https://github.com/coreutils/coreutils/blob/master/src/yes.c The core is about 70 lines. As for over-optimising it, I think chesterton's fence needs mentioning https://fs.blog/2020/03/chestertons-fence/ https://fs.blog/2020/03/chestertons-fence/ I don't think this is a useful avenue of debate for me.