3 ms·

can someone expound on what this does exactly and how it works? Will the compiler try to statically verify that it is actually pure and error if it can't? Does

• nepeckman 8y ago
  Yes and yes. From the manual: > If none of its parameters have the type var T or ref T or ptr T this means no locations are modified. It is a static error to mark a proc/iterator to have no side effect if the compiler cannot verify this. I'm not sure how many compiler optimizations are possible, but I do know that procs marked with no side effect are automatically considered thread safe.
  • e12e 8y ago
    What if your func iamsafe calls the proc imodifyglobals? More generally, can a "func" call a proc and remain a func?
    • nepeckman 8y ago
      I'm not really a Nim expert, but I did a quick test on the scenario you laid out with these results: iamsafe could not call imodifyglobals, but could call a proc with no side effects. I'd guess that a func can call out to any proc that the compiler knows is side effect free, with the compiler erring on the side of caution.
      • dom96 8y ago
        Yep, AFAIK the compiler will do its best to infer the effects and most of the time it does a pretty good job.
    • PMunch 8y ago
      Nope, it can only call other side-effect free things. Note however if you call a procedure from a function the function will try to see if the proc is actually side effect free, just not marked as such. So you can still call a proc, but only if it could've been a func.