The Functor Pattern in C++

The Functor Pattern in C++(fpcomplete.com)

63 points by PopaL 13 years ago | 15 comments

C++ is a powerful language, but with awful syntax and semantics that can discourage experimentation. Since I started using Haskell just over a year ago, my C++ code is much improved—because I can figure things out quickly in Haskell, then translate them to (somewhat write-only) C++. That I think is a large part of what people mean when they say “Haskell makes me a better programmer”. Not only is it a good language in its own right, but it also helps you prototype software that you need to implement in another language for reasons other than language power.

kombine 13 years ago | |

"C++ is a powerful language, but with awful syntax and semantics that can discourage experimentation."

Then you should try out D. Bartosz Milewski in fact has been involved in D development for a long time. It certainly makes it easier to apply a lot of the FP techniques.

evincarofautumn 13 years ago | | |

I have experimented a little bit with D, and really like some of the things in the standard library, but Haskell is already serving as my replacement for C++. D is a viable alternative to C++ for most purposes, though.

I’m actually working on a compiler for a high-performance functional language, to serve in those cases when I would want to go back to C++…

Oxryly 13 years ago | |

You had me until "somewhat write-only." Sounds like you are poisoning your code-base with square functional pegs in round C++ holes...

evincarofautumn 13 years ago | | |

Hardly. Given a choice between complex imperative code and complex functional code, I’ll take the latter. It’s just that the resultant C++ is somewhat brittle and not as thoroughly verified as the Haskell version. I would say the same thing if I wrote something in Coq, proved it correct, then ported it to Haskell.

16s 13 years ago |

std::function is really nice. I've started using it everywhere.

evincarofautumn 13 years ago | |

If only it didn’t use dynamic allocation…ah well. The value is worth the cost.

keveman 13 years ago | | |

I don't think std::function does any dynamic allocation when you initialize it with simple functions. When you initialize it with function objects or lambda expression, most, if not all implementations use the small object optimization to avoid dynamic allocation when possible.

repsilat 13 years ago | |

In this case it's probably unnecessary. It's probably better to template these higher-order functions on their function arguments and just return the lambda itself instead of returning it in a function wrapper.

rosejn 13 years ago |

...or why types and the lack of anonymous functions combine to make a language painful, ugly, and annoying.

systems 13 years ago | |

C++11 does have anonymous functions

http://www.cprogramming.com/c++11/c++11-lambda-closures.html http://stackoverflow.com/questions/7627098/what-is-a-lambda-...

kombine 13 years ago | |

Types certainly don't.