It's easy to write horrific code in any language, high or low level. From what I've seen, both the Linux kernel and git are clean and very readable. In general,

It's easy to write horrific code in any language, high or low level. From what I've seen, both the Linux kernel and git are clean and very readable. In general, I'll take well-written C over poorly-written Python (I'm not implying anything about Mercurial here) or poorly-written OCaml. Git has historically had a few bugs with some high-level commands not correctly reacting to errors in lower-level commands, but they have been largely squashed in recent releases. The low-level commands have always been pretty solid, and the git repository format has been stable for a long, long time now. So in summary, I wouldn't be too concerned about the implementation language of choice. It's always about the maker, not about the tools.