I really like that you have to use `env` in fish, since it's cross-shell - it works in bash/zsh/dash/whatever. The `A=b foo` syntax is an unnecessary appendix in the syntax that complicates matters while only saving 4 characters.
cd build && LD_LIBRARY_PATH=../lib ./foo
:/It's no dealbreaker though, I still use fish and love it :) Just a minor annoyance ;)