In functional languages “explicit” also means “…and don’t have my functions depend on external state if it can be at all helped, please”. Obviously when you work with files, console I/O, network etc. then it’s unavoidable. But “explicit” in the context of this thread carries the extra context of “functions should be idempotent and self-sufficient”.
Which also has its limits. As I mentioned in a previous comment, you wouldn’t want to specify your DB credentials on every call; in such cases having implicit state (the DB credentials, adapter, pooling options etc.) which is persisted and loaded from a non-obvious agent is still convenient. And as long as the programmers in the team don’t forget about these special cases – and keep them to a minimum – then a good balance between minimum WTFs/minute and convenience is achieved.
