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Show HN: I built a poker site with Haskell

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Re: Show HN: I built a poker site with Haskell

#21

Post by chowells »

daenz wrote: post #8
w0utert wrote: post #2

So, I know literally nothing about Haskell, and I would rate my knowledge of functional programming theory as 'beginner' at best, but I still get baffled every time when reading Haskell code that implements anything other than something trivial like a fibonacci sequence. The poker server code looks extremely tidy and well engineered, so that can't be the problem, but to me it's utterly incomprehensible. It seems like…

Haskell is dense. I'm picking it up now[0], so this project was very useful for me to see how some "real world" Haskell is written. But yes, take for example this function getSocketAPIPort :: Int -> IO Int getSocketAPIPort defaultPort = do maybeEnvPort return defaultPort Just port -> maybe (return defaultPort) return (readMaybe port) It gets a port from an environment variable, if it can, otherwise a default port. Co…

Ouch. That function is actually written in a pretty convoluted and redundant way.

    getSocketAPIPort :: Int -> IO Int
    getSocketAPIPort defaultPort = do
        maybeEnvPort >= readMaybe
That's starting to border on over-terse, so you could expand the bind operator into do notation if you wanted to spread it out a bit further. On the other hand, it's also starting to feel over-verbose, using do notation for only a single IO action. Maybe...

    getSocketAPIPort :: Int -> IO Int
    getSocketAPIPort defaultPort = fromMaybe defaultPort . (readMaybe = lookupEnv "socketPort"
That might be going too far. But maybe it's what I'd write. Just depends on how much I expect to make this more complicated in the future. This form has the simplest flow to read. I mean... it's dense. Really dense. But it has the fewest total things going on, and it neatly divides into three interesting parts, easily understood in isolation, plumbed together with two common combinators. But it's also pretty rigid in structure. If you ever want to add other sources for finding the port or change the priorities of them, that form would need to be totally rewritten, and probably would end up back in do notation.

But in every case, all the various return calls should be combined into one (or none, if you use fmap or ), and the fallback to the default should only be written once.

Re: Show HN: I built a poker site with Haskell

#22

Post by jakear »

chucky_z wrote: post #16
anchpop wrote: post #5

Earlier quoted context omitted.

I think part of the problem is that Haskell code can be very terse. When reading Python I expect to be able to easily understand what's going on in a 5 line function because the pythonic style limits what you can do in 5 lines. But in haskell a 5 line function can be pretty sophisticated.

Careful about sweeping generalizations... The internet has shown what is possible in "one line" of python, and I've seen this in the real world scarily enough!

What you can accomplish in 5 lines of “ready for production, maintainable, easily understandable by coworkers” python is vastly less than what you can accomplish in 5 lines of similarly constrained Haskell.

Re: Show HN: I built a poker site with Haskell

#23

Post by mrkeen »

daenz wrote: post #8
w0utert wrote: post #2

So, I know literally nothing about Haskell, and I would rate my knowledge of functional programming theory as 'beginner' at best, but I still get baffled every time when reading Haskell code that implements anything other than something trivial like a fibonacci sequence. The poker server code looks extremely tidy and well engineered, so that can't be the problem, but to me it's utterly incomprehensible. It seems like…

Haskell is dense. I'm picking it up now[0], so this project was very useful for me to see how some "real world" Haskell is written. But yes, take for example this function getSocketAPIPort :: Int -> IO Int getSocketAPIPort defaultPort = do maybeEnvPort return defaultPort Just port -> maybe (return defaultPort) return (readMaybe port) It gets a port from an environment variable, if it can, otherwise a default port. Co…

If you've wandered in from another language and are wondering what it might look like in a less terse language, here's an attempt:

    static IO getSocketApiPort(@NotNull final Integer defaultPort) {
      return lookupEnv("socketPort")
        .flatMap((Optional maybeEnvPort) -> {
          if(!maybeEnvPort.isPresent()) {
            return IO.of(defaultPort);
          } else {
            String strEnvPort = maybeEnvPort.get();
            Optional envPort = readMaybe(strEnvPort);
            return IO.of(envPort.orElse(defaultPort));
          }
        });
    }

Re: Show HN: I built a poker site with Haskell

#24

Post by dbelford »

InvOfSmallC wrote: post #12

What would be the best IDE/editor for Haskell?

I'm curious about this too.

Every once in a while I try going through the editor setups in this chart - https://github.com/rainbyte/haskell-ide-chart. But I run into lots of friction in any one I try. Between using the REPL, getting harmony in the project libraries and the IDE engine libraries, and learning a new editor, I run out of energy to also learn the language ecosystem (libraries, concepts, idioms, package managers).

An IDE that that surfaced everything the language encodes seems like it would lower the learning curve of Haskell. And every year it seems a little closer. Is there anything close to a jetbrains/visual studio/xcode yet?

It seems like all the type safety would be valuable enough that companies would pay for/invest in the ecosystem. Learning the ecosystem has been more challenging than learning the language at this point for me.

Re: Show HN: I built a poker site with Haskell

#25

Post by c3534l »

_hao wrote: post #14

Trying to read Haskell code without any knowledge of it is interesting to say the least. I like how compact it looks, but I'm guessing a lot of the simple looking statements (at least at first glance) do a lot under the hood. Is that a characteristic of Haskell itself or just the developer has a good style?

Haskell tends to be terse because a number of features and very general built in functions. The author is also good at Haskell and lacks a lot of ugly optimizations making it look even cleaner.

Re: Show HN: I built a poker site with Haskell

#27

Post by [deleted] »

daenz wrote: post #8
w0utert wrote: post #2

So, I know literally nothing about Haskell, and I would rate my knowledge of functional programming theory as 'beginner' at best, but I still get baffled every time when reading Haskell code that implements anything other than something trivial like a fibonacci sequence. The poker server code looks extremely tidy and well engineered, so that can't be the problem, but to me it's utterly incomprehensible. It seems like…

Haskell is dense. I'm picking it up now[0], so this project was very useful for me to see how some "real world" Haskell is written. But yes, take for example this function getSocketAPIPort :: Int -> IO Int getSocketAPIPort defaultPort = do maybeEnvPort return defaultPort Just port -> maybe (return defaultPort) return (readMaybe port) It gets a port from an environment variable, if it can, otherwise a default port. Co…

[deleted]

Re: Show HN: I built a poker site with Haskell

#28

Post by thedufer »

jakear wrote: post #22
chucky_z wrote: post #16

Earlier quoted context omitted.

Careful about sweeping generalizations... The internet has shown what is possible in "one line" of python, and I've seen this in the real world scarily enough!

What you can accomplish in 5 lines of “ready for production, maintainable, easily understandable by coworkers” python is vastly less than what you can accomplish in 5 lines of similarly constrained Haskell.

Unfortunately, a lot of work there is done by the Haskell community having utterly absurd standards for those things. I work in a different functional programming language, and you would not believe the amount of time I spend convincing new hires with Haskell backgrounds to spend the extra few characters to expand out the unreadable point-free/single-character-names style that Haskell folks prefer.

Re: Show HN: I built a poker site with Haskell

#30

Post by llimllib »

chowells wrote: post #21
daenz wrote: post #8

Earlier quoted context omitted.

Haskell is dense. I'm picking it up now[0], so this project was very useful for me to see how some "real world" Haskell is written. But yes, take for example this function getSocketAPIPort :: Int -> IO Int getSocketAPIPort defaultPort = do maybeEnvPort return defaultPort Just port -> maybe (return defaultPort) return (readMaybe port) It gets a port from an environment variable, if it can, otherwise a default port. Co…

Ouch. That function is actually written in a pretty convoluted and redundant way. getSocketAPIPort :: Int -> IO Int getSocketAPIPort defaultPort = do maybeEnvPort >= readMaybe That's starting to border on over-terse, so you could expand the bind operator into do notation if you wanted to spread it out a bit further. On the other hand, it's also starting to feel over-verbose, using do notation for only a single IO act…

tbf, I (as a person with some very basic haskell understanding) can more or less read the parent's code, but can't make heads or tails out of yours.

"Convoluted and redundant" is in the eye of the beholder I guess

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