But writing a program is all about expressing your intent in a programming language, step by step. It's about "communicating" with the machine (and your users).
And your coworkers, and 'you a year from now'. For the love of god have some compassion with 'you a year from now' and save him a day of debugging.
The linked page shows "Fachidiot" is also used as a German loanword in English (although maybe not that often; I've never seen it used in the wild)