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With Scala you feel smart having just got something to work in a beautiful way but when you look around the room to tell your clojure colleague how clever you a

With Scala you feel smart having just got something to work in a beautiful way but when you look around the room to tell your clojure colleague how clever you are, you notice he left 3 hours ago and there is a post-it saying use a Map So he was making reference to Clojure here. That's fine, but you don't have to make things complicated in Scala if you don't want to. I love the semantics of Clojure, but until you get some optional typing and possibly another syntax baked in forget about it for a whole class of devs.

lkrubner 13y ago
About this: "until you get some optional typing" There is work being done on an optional type system: https://github.com/clojure/core.typed https://github.com/clojure/core.typed There are also some interesting experiments in enforcing specific data structures: https://github.com/prismatic/schema https://github.com/prismatic/schema Much effort has been made to make contract programming easy in Clojure: https://github.com/clojure/core.contracts https://github.com/clojure/core.contracts And if you would feel the urge to respond with something like "why is such important functionality in a library", I'll point out enforcing pre and post conditions (on a function) has a nice syntax that is part of the language: http://blog.fogus.me/2009/12/21/clojures-pre-and-post/ http://blog.fogus.me/2009/12/21/clojures-pre-and-post/ I find that every time I read an article about Scala I am left wondering "Why don't these people just use Clojure?"
- michaelochurch 13y ago
  This is why I'm really happy with the Clojure community. People in Clojure get that types are useful and important. You don't have the "I don't understand that, so I'm going to call it unimportant" attitude. Instead, you have people using Clojure as a lens to explore and, one hopes, solve the problem-- even when it seems so difficult as to be almost infeasible (such as static typing on a Lisp). Clojure is a dynamically typed, JVM language-- now. (However, ClojureScript is also pretty far along.) It might not always be that way. It will evolve according to the needs of computer science over the next 20+ years.
  - nickik 13y ago
    > even when it seems so difficult as to be almost infeasible That is quite fun. Lisp had experiments with static types for a long long time. Look at things like Qi and there history.
- kasey_junk 13y ago
  Having made the choice between Clojure and Scala many times, always in favor of Scala, here are the 3 main reasons I keep going back to Scala (even though I don't particularly like it): 1. I like type systems. I want strong typing, I'd prefer stronger typing in Scala (ie purity constraints as type information etc). I don't want optional typing (if I need dynamic interop, I can make a case for opt-out typing, but I've never needed). 2. Performance. I spend a lot of time dealing with performance issues, specifically latency & throughput. I often have to back off of idiomatic Scala to achieve these goals (especially when it comes to GC pressure). Scala makes that easy & painless. Clojure doesn't. 3. Style (purely subjective). I don't like LISP style languages. My very first experience in programming is in Scheme, so it's not that, I just don't like how they look. It's fine for other folks to like them, different strokes and all that, but I don't like it. There are a ton of things I don't like about Scala, but for me and my projects, right now, if I'm targeting the JVM it is the best choice and Clojure isn't even second.
  - nickik 13y ago
    > 1. I like type systems. I believe with schema you can get much of the same benefit and even more on top of that. I think schema will still evolve and work together with core.typed (witch will also evolve) will be a awesome combo. I generally prefer not having to right the types but putting down some automatically enforced documentation is nice once in a while. > 2. Performance. I spend a lot of time dealing with performance issues, specifically latency & throughput. I cant really say on this issue. But I know that the story here really changed and keeps changing. Because of macros we get library's that are where fast but feel easy and simple to use. Some teams like prismatic, runa and relevance did some pretty performant APIs and used Clojure.
  - Aqueous 13y ago
    "I often have to back off of idiomatic Scala to achieve these goals (especially when it comes to GC pressure). " Can you give an example of when you had to do this? I often wonder about the performance costs of chaining together several collection API calls.
    - 13y ago
nickik 13y ago
> but until you get some optional typing The schema library form the prismatic guys should be what you want, its pretty powerful. https://github.com/prismatic/schema https://github.com/prismatic/schema Aria Haghighi - Prismatic's Schema for Server and Client-Side Data Shape Declaration and Validation (http://www.youtube.com/watch?v=o_jtwIs2Ot8&list=PLZdCLR02grLpFFB54kq3FU5A0_C94l2WF&index=15 http://www.youtube.com/watch?v=o_jtwIs2Ot8&list=PLZdCLR02grL...) For static type checking: https://github.com/clojure/core.typed https://github.com/clojure/core.typed > possibly another syntax baked in Not needed in my mind. I would rather have less devs then C syntax. Not trying to be elitist but clojure will never not be a lisp, and if somebody can move from a(b) to (a b) then let him do python.
pkinsky 13y ago
>With Scala you feel smart having just got something to work in a beautiful way but when you look around the room to tell your clojure colleague how clever you are, you notice he left 3 hours ago and there is a post-it saying use a Map I don't get this. Scala has a great collections library, including a Map type. What, exactly, is the author complaining about?
- nickik 13y ago
  His point is that Scala and the Scala community dont just use maps, they always want everything in types and that is why every library does it that way. Its bad practice just to use a map. In Clojure land its the other way around even if we put something in a type (deftype) we right interface to make it look like its not (defrecord). Its not what is possible, but what is. And the fact is that all the Clojure web framework and library's use the same data structure even if the underlying implementation is different. See how ring uses much of the same thing as the pedestal service.
  - yummyfajitas 13y ago
    Yes, and there is a good reason why Scalaland uses types. Consider a Spray-like API using only maps: val cookies = Map("sessionid" -> "1234567") val headers = Map("Content-Type" -> "application/javascript") setCookies(headers) { setHeaders(headers) { complete { obj } } } With Scala's "make everything a different type" approach, that's a compile error - setCookies will expect a List[Cookie], not a List[HttpHeader]. Those of us living in Scalaland are not as smart as the Clojure guys. We make mistakes sometimes and find it handy when the compiler yells at us.
    - kasey_junk 13y ago
      This is actually a good example of something I don't like in Scala. They don't make this sort of differentiation easy enough. Adding a Haskell style newtype would be really, really useful.
      - 13y ago

lkrubner 13y ago

About this: "until you get some optional typing" There is work being done on an optional type system: https://github.com/clojure/core.typed https://github.com/clojure/core.typed There are also some interesting experiments in enforcing specific data structures: https://github.com/prismatic/schema https://github.com/prismatic/schema Much effort has been made to make contract programming easy in Clojure: https://github.com/clojure/core.contracts https://github.com/clojure/core.contracts And if you would feel the urge to respond with something like "why is such important functionality in a library", I'll point out enforcing pre and post conditions (on a function) has a nice syntax that is part of the language: http://blog.fogus.me/2009/12/21/clojures-pre-and-post/ http://blog.fogus.me/2009/12/21/clojures-pre-and-post/ I find that every time I read an article about Scala I am left wondering "Why don't these people just use Clojure?"

michaelochurch 13y ago
This is why I'm really happy with the Clojure community. People in Clojure get that types are useful and important. You don't have the "I don't understand that, so I'm going to call it unimportant" attitude. Instead, you have people using Clojure as a lens to explore and, one hopes, solve the problem-- even when it seems so difficult as to be almost infeasible (such as static typing on a Lisp). Clojure is a dynamically typed, JVM language-- now. (However, ClojureScript is also pretty far along.) It might not always be that way. It will evolve according to the needs of computer science over the next 20+ years.
- nickik 13y ago
  > even when it seems so difficult as to be almost infeasible That is quite fun. Lisp had experiments with static types for a long long time. Look at things like Qi and there history.
kasey_junk 13y ago
Having made the choice between Clojure and Scala many times, always in favor of Scala, here are the 3 main reasons I keep going back to Scala (even though I don't particularly like it): 1. I like type systems. I want strong typing, I'd prefer stronger typing in Scala (ie purity constraints as type information etc). I don't want optional typing (if I need dynamic interop, I can make a case for opt-out typing, but I've never needed). 2. Performance. I spend a lot of time dealing with performance issues, specifically latency & throughput. I often have to back off of idiomatic Scala to achieve these goals (especially when it comes to GC pressure). Scala makes that easy & painless. Clojure doesn't. 3. Style (purely subjective). I don't like LISP style languages. My very first experience in programming is in Scheme, so it's not that, I just don't like how they look. It's fine for other folks to like them, different strokes and all that, but I don't like it. There are a ton of things I don't like about Scala, but for me and my projects, right now, if I'm targeting the JVM it is the best choice and Clojure isn't even second.
- nickik 13y ago
  > 1. I like type systems. I believe with schema you can get much of the same benefit and even more on top of that. I think schema will still evolve and work together with core.typed (witch will also evolve) will be a awesome combo. I generally prefer not having to right the types but putting down some automatically enforced documentation is nice once in a while. > 2. Performance. I spend a lot of time dealing with performance issues, specifically latency & throughput. I cant really say on this issue. But I know that the story here really changed and keeps changing. Because of macros we get library's that are where fast but feel easy and simple to use. Some teams like prismatic, runa and relevance did some pretty performant APIs and used Clojure.
- Aqueous 13y ago
  "I often have to back off of idiomatic Scala to achieve these goals (especially when it comes to GC pressure). " Can you give an example of when you had to do this? I often wonder about the performance costs of chaining together several collection API calls.
  - 13y ago

nickik 13y ago

> but until you get some optional typing The schema library form the prismatic guys should be what you want, its pretty powerful. https://github.com/prismatic/schema https://github.com/prismatic/schema Aria Haghighi - Prismatic's Schema for Server and Client-Side Data Shape Declaration and Validation (http://www.youtube.com/watch?v=o_jtwIs2Ot8&list=PLZdCLR02grLpFFB54kq3FU5A0_C94l2WF&index=15 http://www.youtube.com/watch?v=o_jtwIs2Ot8&list=PLZdCLR02grL...) For static type checking: https://github.com/clojure/core.typed https://github.com/clojure/core.typed > possibly another syntax baked in Not needed in my mind. I would rather have less devs then C syntax. Not trying to be elitist but clojure will never not be a lisp, and if somebody can move from a(b) to (a b) then let him do python.

pkinsky 13y ago

>With Scala you feel smart having just got something to work in a beautiful way but when you look around the room to tell your clojure colleague how clever you are, you notice he left 3 hours ago and there is a post-it saying use a Map I don't get this. Scala has a great collections library, including a Map type. What, exactly, is the author complaining about?

nickik 13y ago
His point is that Scala and the Scala community dont just use maps, they always want everything in types and that is why every library does it that way. Its bad practice just to use a map. In Clojure land its the other way around even if we put something in a type (deftype) we right interface to make it look like its not (defrecord). Its not what is possible, but what is. And the fact is that all the Clojure web framework and library's use the same data structure even if the underlying implementation is different. See how ring uses much of the same thing as the pedestal service.
- yummyfajitas 13y ago
  Yes, and there is a good reason why Scalaland uses types. Consider a Spray-like API using only maps: val cookies = Map("sessionid" -> "1234567") val headers = Map("Content-Type" -> "application/javascript") setCookies(headers) { setHeaders(headers) { complete { obj } } } With Scala's "make everything a different type" approach, that's a compile error - setCookies will expect a List[Cookie], not a List[HttpHeader]. Those of us living in Scalaland are not as smart as the Clojure guys. We make mistakes sometimes and find it handy when the compiler yells at us.
  - kasey_junk 13y ago
    This is actually a good example of something I don't like in Scala. They don't make this sort of differentiation easy enough. Adding a Haskell style newtype would be really, really useful.
    - 13y ago