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I disagree with that. Haskell is category theory as a language. The Scala community got invaded by Haskellites trying to turn Scala into Haskell, but there’s a

by jowiar 8y ago

I disagree with that. Haskell is category theory as a language. The Scala community got invaded by Haskellites trying to turn Scala into Haskell, but there’s a particular style of OOP/FP hybrid that requires a language like Scala to use/teach/explore. The problem is that in creating the tool to enable that, we ended up with a language that was too big to have a coherent style, which led to an incredibly fractured community.

nextos 8y ago
Designing good multi-paradigm languages is very hard. I'm a big fan of Mozart-Oz and Common Lisp, and I think Odersky did a really good job with Scala. In fact, given that Common Lisp is languishing and Mozart was never a serious real world contender, Scala fills in a niche where there are not many competitors. C++, just for some use cases, Julia for others, and .NET. The fact that many organizations working on massive datasets have embraced Scala proves there are not many alternatives around, sadly.
- auvi 8y ago
  > Common Lisp is languishing can you elaborate more on that?
  - nextos 8y ago
    I don't think CL is attracting a lot of new developers or there's a lot of new libraries getting developed. But I would be glad to be proven wrong. Perhaps Racket will eventually become a CL replacement, now it's adopting a lot of Chez low-level stuff and it's multiparadigm efforts keep growing.
    - joshlemer 8y ago
      Do you have any ideas why Racket has not had the commercial success of Clojure for example?
      - didibus 8y ago
        My guess would be the JVM. Racket is an academic language, designed for academia. At least it markets itself as such. Made to explore the design space of programming languages. Clojure was designed and marketed for the enterprise. Builds on the JVM, full Java interop, emphasis on pragmatism.
YorkshireSeason 8y ago
Haskell is category theory as a language. I disagree with this. Haskell's creation [1, 2] predates the realisation (by the FP community at large) of the close connection between parts of category theory and parts of pure functional programming, which happened in the 1990s, perhaps driven by Moggi's realisation that monads are a fundamental abstraction in computation that can reconcile effects with pure functional computation. More importantly, there is no category "Hask" of Haskell programs, and there isn't even a candidate category that's even close. One of Odersky's motives in creating Scala was bringing the power of Haskell into the JVM world, although this is not the only motive (tight integration of OO and FP being another). Haskell's key innovation over its predecessors (Miranda and ML) was the addition of higher-kinded types, which in turn made ad-hoc polymorphism digestable in a typed world (in the form of type-classes). The combination of HKTs and type-classes enables the monadic abstractions that contemporary Haskell programming is widely known for today. Note that Scala has HKTs and type classes (via implicits), so Haskell programs can typically transliterated into idiomatic Scala without major complications. [1] P. Hudak, J. Hughes, S. Peyton Jones, P. Wadler, A History of Haskell: Being Lazy With Class. http://haskell.cs.yale.edu/wp-content/uploads/2011/02/history.pdf http://haskell.cs.yale.edu/wp-content/uploads/2011/02/histor... [2] Interview with Simon Peyton-Jones. http://www.cs.cmu.edu/~popl-interviews/peytonjones.html http://www.cs.cmu.edu/~popl-interviews/peytonjones.html [3] E. Moggi, Notions of Computation and Monads. https://core.ac.uk/download/pdf/21173011.pdf https://core.ac.uk/download/pdf/21173011.pdf
- jowiar 8y ago
  Would love to see a citation re: Odersky (or if he'd chime in here). My general assumption is that if Scala was intended to be category theory, implemented, something along the lines of scalaz or cats would have been built into the language -- the philosophy of the language does not include a JS-esque philosophy of small stdlib, big library ecosystem.
  - yawaramin 8y ago
    See this talk https://youtu.be/P8jrvyxHodU https://youtu.be/P8jrvyxHodU He mentions module systems fairly early on.
tathougies 8y ago
> I disagree with that. Haskell is category theory as a language No it is really not. Haskell only really has one category of any import, typically denoted 'Hask'. There is no builtin way to embed or express arbitrary categories in Haskell. It's not even clear what this would mean, given that Haskell only has one conception of arrow (the function type '->'). In fact, Haskell is so far removed from true category theory that we have to use a compiler plugin (CCC by Conal Elliot) to get anything approaching compilation to arbitrary categories. Haskell is based on the polymorphically typed lambda calculus. Some decades after its design, some people realized they could use some abstract algebra concepts to help structure programs. You can use these concepts in any language with a sufficiently expressive type system. It is not specific to Haskell

by jowiar 8y ago

nextos 8y ago

Designing good multi-paradigm languages is very hard. I'm a big fan of Mozart-Oz and Common Lisp, and I think Odersky did a really good job with Scala. In fact, given that Common Lisp is languishing and Mozart was never a serious real world contender, Scala fills in a niche where there are not many competitors. C++, just for some use cases, Julia for others, and .NET. The fact that many organizations working on massive datasets have embraced Scala proves there are not many alternatives around, sadly.

auvi 8y ago
> Common Lisp is languishing can you elaborate more on that?
- nextos 8y ago
  I don't think CL is attracting a lot of new developers or there's a lot of new libraries getting developed. But I would be glad to be proven wrong. Perhaps Racket will eventually become a CL replacement, now it's adopting a lot of Chez low-level stuff and it's multiparadigm efforts keep growing.
  - joshlemer 8y ago
    Do you have any ideas why Racket has not had the commercial success of Clojure for example?
    - didibus 8y ago
      My guess would be the JVM. Racket is an academic language, designed for academia. At least it markets itself as such. Made to explore the design space of programming languages. Clojure was designed and marketed for the enterprise. Builds on the JVM, full Java interop, emphasis on pragmatism.

YorkshireSeason 8y ago

Haskell is category theory as a language. I disagree with this. Haskell's creation [1, 2] predates the realisation (by the FP community at large) of the close connection between parts of category theory and parts of pure functional programming, which happened in the 1990s, perhaps driven by Moggi's realisation that monads are a fundamental abstraction in computation that can reconcile effects with pure functional computation. More importantly, there is no category "Hask" of Haskell programs, and there isn't even a candidate category that's even close. One of Odersky's motives in creating Scala was bringing the power of Haskell into the JVM world, although this is not the only motive (tight integration of OO and FP being another). Haskell's key innovation over its predecessors (Miranda and ML) was the addition of higher-kinded types, which in turn made ad-hoc polymorphism digestable in a typed world (in the form of type-classes). The combination of HKTs and type-classes enables the monadic abstractions that contemporary Haskell programming is widely known for today. Note that Scala has HKTs and type classes (via implicits), so Haskell programs can typically transliterated into idiomatic Scala without major complications. [1] P. Hudak, J. Hughes, S. Peyton Jones, P. Wadler, A History of Haskell: Being Lazy With Class. http://haskell.cs.yale.edu/wp-content/uploads/2011/02/history.pdf http://haskell.cs.yale.edu/wp-content/uploads/2011/02/histor... [2] Interview with Simon Peyton-Jones. http://www.cs.cmu.edu/~popl-interviews/peytonjones.html http://www.cs.cmu.edu/~popl-interviews/peytonjones.html [3] E. Moggi, Notions of Computation and Monads. https://core.ac.uk/download/pdf/21173011.pdf https://core.ac.uk/download/pdf/21173011.pdf

jowiar 8y ago
Would love to see a citation re: Odersky (or if he'd chime in here). My general assumption is that if Scala was intended to be category theory, implemented, something along the lines of scalaz or cats would have been built into the language -- the philosophy of the language does not include a JS-esque philosophy of small stdlib, big library ecosystem.
- yawaramin 8y ago
  See this talk https://youtu.be/P8jrvyxHodU https://youtu.be/P8jrvyxHodU He mentions module systems fairly early on.

tathougies 8y ago

> I disagree with that. Haskell is category theory as a language No it is really not. Haskell only really has one category of any import, typically denoted 'Hask'. There is no builtin way to embed or express arbitrary categories in Haskell. It's not even clear what this would mean, given that Haskell only has one conception of arrow (the function type '->'). In fact, Haskell is so far removed from true category theory that we have to use a compiler plugin (CCC by Conal Elliot) to get anything approaching compilation to arbitrary categories. Haskell is based on the polymorphically typed lambda calculus. Some decades after its design, some people realized they could use some abstract algebra concepts to help structure programs. You can use these concepts in any language with a sufficiently expressive type system. It is not specific to Haskell