A workshop on monads with C++14

Eh, when you're doing writing rather than coding, sometimes it's hard to be more descriptive than "added more text." I have a few repositories where I don't care much about the "logic" of the history, but I just want things versioned. (e.g. a folder full of text files with random ideas jotted down.) My commit commands tend to look like,

    git commit -m "`date`"

Re: A workshop on monads with C++14

#5

Post by rsp1984 » Sat, Jan 17, 2015, 10:41 PM UTC

  // must be overloaded
  template class M,typename T,typename F>
  auto operator>>=(const M& m, F f)->decltype(f(std::declval()));

Could someone please point out to me why exactly this is useful and why I would want to code like this? Does it help me solve specific types of problems?

Re: A workshop on monads with C++14

#6

Post by patrick73 » Sat, Jan 17, 2015, 11:13 PM UTC

rsp1984 wrote: post #5

// must be overloaded template class M,typename T,typename F> auto operator>>=(const M & m, F f)->decltype(f(std::declval ())); Could someone please point out to me why exactly this is useful and why I would want to code like this? Does it help me solve specific types of problems?

I think this is worth enough for intellectual practice, but honestly, I can't see how this can solve a specific type of problem.

Re: A workshop on monads with C++14

#7

Post by dkarapetyan » Sat, Jan 17, 2015, 11:59 PM UTC

rsp1984 wrote: post #5

// must be overloaded template class M,typename T,typename F> auto operator>>=(const M & m, F f)->decltype(f(std::declval ())); Could someone please point out to me why exactly this is useful and why I would want to code like this? Does it help me solve specific types of problems?

Monads are originally a solution to giving semantics to i/o, exceptions, and other things that fall under the generic headline of side-effecting computations. I'm not sure what value you get out of it when your language isn't Haskell. Here's the paper that started it all: http://www.cs.cmu.edu/afs/cs/user/crary/www/819-f09/Moggi91.....

Re: A workshop on monads with C++14

#8

Post by TheOtherHobbes » Sun, Jan 18, 2015, 12:16 AM UTC

dkarapetyan wrote: post #2

Template template templates. I didn't know that was thing.

C++ repeats itself, first as tragedy, then as farce.

Re: A workshop on monads with C++14

#9

Post by whoopdedo » Sun, Jan 18, 2015, 2:05 AM UTC

rsp1984 wrote: post #5

// must be overloaded template class M,typename T,typename F> auto operator>>=(const M & m, F f)->decltype(f(std::declval ())); Could someone please point out to me why exactly this is useful and why I would want to code like this? Does it help me solve specific types of problems?

It looks like he's using template metaprogramming so he can write C++ as if it were Haskell.

So why not just use Haskell?