Show HN: C++ runtime/compile-time detection in constexpr functions • Hacker News Board

Re: Show HN: C++ runtime/compile-time detection in constexpr functions

#11

Post by billsix » Tue, Aug 08, 2017, 11:57 PM UTC

In my libbug library, computation at Compile-Time uses the exact same language as the run-time

  {at-both-times
   {define fact
     [|n| (if (= n 0)
              [1]
              [(* n (fact (- n 1)))])]}}

  (pp {at-compile-time-expand   (fact 3)})
  (pp (fact 3))

https://github.com/billsix/bug

Re: Show HN: C++ runtime/compile-time detection in constexpr functions

#12

Post by fumigator » Wed, Aug 09, 2017, 12:51 AM UTC

Typo detected :)

"An approach for runtime dection inside a constexpr function"

https://github.com/SaadAhmad/in_constexpr

Re: Show HN: C++ runtime/compile-time detection in constexpr functions

#13

Post by CuriousThinker » Wed, Aug 09, 2017, 12:58 AM UTC

fumigator wrote: post #12

Typo detected :) "An approach for runtime dection inside a constexpr function" https://github.com/SaadAhmad/in_constexpr

Thanks!

Re: Show HN: C++ runtime/compile-time detection in constexpr functions

#14

Post by nicwilson » Wed, Aug 09, 2017, 1:34 AM UTC

As with most things in C++ that looks horribly convoluted for some very simple functionality. In D all we have to do is:

* `if ( __ctfe) { ... }` for compile time

* `if (!__ctfe) { ... }` for runtime

Re: Show HN: C++ runtime/compile-time detection in constexpr functions

#15

Post by VHRanger » Wed, Aug 09, 2017, 1:42 AM UTC

nicwilson wrote: post #14

As with most things in C++ that looks horribly convoluted for some very simple functionality. In D all we have to do is: * `if ( __ctfe) { ... }` for compile time * `if (!__ctfe) { ... }` for runtime

I don't think it's any secret D does CTFE better than any other language.

Re: Show HN: C++ runtime/compile-time detection in constexpr functions

#16

Post by logicchains » Wed, Aug 09, 2017, 4:17 AM UTC

VHRanger wrote: post #15

nicwilson wrote: post #14

As with most things in C++ that looks horribly convoluted for some very simple functionality. In D all we have to do is: * `if ( __ctfe) { ... }` for compile time * `if (!__ctfe) { ... }` for runtime

I don't think it's any secret D does CTFE better than any other language.

Better than Common Lisp?

Re: Show HN: C++ runtime/compile-time detection in constexpr functions

#17

Post by heja_bruh » Wed, Aug 09, 2017, 5:21 AM UTC

Another reason why we should not be using c++...

Re: Show HN: C++ runtime/compile-time detection in constexpr functions

#18

Post by zerr » Wed, Aug 09, 2017, 5:49 AM UTC

logicchains wrote: post #16

VHRanger wrote: post #15

Earlier quoted context omitted.

I don't think it's any secret D does CTFE better than any other language.

Better than Common Lisp?

Does better AND doesn't require the language to be AST :)

Re: Show HN: C++ runtime/compile-time detection in constexpr functions

#19

Post by minipci1321 » Wed, Aug 09, 2017, 6:31 AM UTC

Why to mlock() the page? And since the code is already specific to linux/gcc/clang, why not to assign the flag to a read-write section (__attribute__((section(name))) -- should allow to get rid of mprotect()?

Re: Show HN: C++ runtime/compile-time detection in constexpr functions

#20

Post by junke » Wed, Aug 09, 2017, 7:53 AM UTC

zerr wrote: post #18

logicchains wrote: post #16

Earlier quoted context omitted.

Better than Common Lisp?

Does better AND doesn't require the language to be AST :)

The joke's on you, working with an AST is a treat :)