问题
They say that use exclamation marks when naming impure functions.
But I don't exactly understand the "impure" functions. Are they
- functions change state of their arguments (via reset!, alter, java-object-methods, ...)
- functions occur side-effect (for example, print, spit, ...)
- or both?
Obviously, official clojure apis don't have bang!s on every case above. I wonder when should I put them and need your help to make my code saner.
回答1:
I would say you don't need to put ! on every impure function. Community Clojure Style Guide recommends:
The names of functions/macros that are not safe in STM transactions should end with an exclamation mark.
So, basically, end with ! functions that change state for atoms, metadata, vars, transients, agents and io as well.
Thanks to @noisesmith for update.
来源：https://stackoverflow.com/questions/20606249/when-to-use-exclamation-mark-in-clojure-or-lisp