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I thought that, besides the JVM itself, the advantages of Clojure would be its concurrency model - as CL standard doesn't define anything related to this - and

I thought that, besides the JVM itself, the advantages of Clojure would be its concurrency model - as CL standard doesn't define anything related to this - and its stronger functional approach. I don't fully grasp the advantages of being a Lisp-1 or Lisp-2 :)

pjmlp 14y ago
> I don't fully grasp the advantages of being a Lisp-1 or Lisp-2 :) It has to do with variable scoping. Lisp-1 only accepts lexical scoping, while Lisp-2 also allows for dynamic scoping. http://www.nhplace.com/kent/Papers/Technical-Issues.html http://www.nhplace.com/kent/Papers/Technical-Issues.html
- mahmud 14y ago
  Good grief. No. Lisp-N has to do with the number of name spaces in the language. Lisp-1s only have ONE environment; the variables range over all values of the language, integers, functions, vectors, symbols, strings. In Lisp-N, there are N namespaces for each "kind" of value. Common Lisp is called a "Lisp-2" because it separates functions from other values. (it's closer to Lisp-5 or even Lisp-7, forgot which, because it allows that many kinds of "names" without collission. Also above you said Clojure "probably" has better data structures than Common Lisp. That is unsubstantiated.
  - yoklov 14y ago
    For what it's worth, Clojure has implementations of Phil Bagwell's HAMT-based hash-maps, vectors, and sets. These are absolutely amazing data structures, and offer functional updates, a list-like API (O(log_32(n)) for most operations, which ends up being less than seven operations in practice, which is similar enough to O(1) for most programmers). I'm not much of a common lisp programmer (mostly sticking with scheme/racket and Clojure), but I don't think they've been ported to Common Lisp (yet), so the claim that Clojure has better data structures than Common Lisp, while somewhat a matter of preference, isn't entirely unsubstantiated.
    - mahmud 14y ago
      Common Lisp has hash-tables, vectors, and sets .. had it, in an ANSI-specified document since 1984. The implementation details of these is, well, implementation dependent, be they HAMT or whatever. The language provides a wealth of tools out of the box, but it's the job of the programmer to choose more appropriate tools for the problems at hand. The following is the Common Lisp specification. 12+ implementations, half of them industrial strength, more than half commercial vendors, and everyone of them has to adhere to this spec: http://www.franz.com/support/documentation/8.2/ansicl/ansicl.htm http://www.franz.com/support/documentation/8.2/ansicl/ansicl...
      - jules 14y ago
        Note that CL's data structures are mutable, whereas Clojure's are persistent.
        swah 14y ago
        Google search saver: immutable = persistent
      - swannodette 14y ago
        But does Common Lisp allow multiple implementations of those data structures to exist in the same program actually allowing programmers to utilize the best tool for the job?
        mahmud 14y ago
        Are you seriously asking me if a programming language allows for the implementation of data-structures? If you mean can users extend the core CL data-types, no, but you have a wealth of tools to do that yourself; use generic functions to implement whatever interface you wish, then provide for specific implementations.
        swannodette 14y ago
        but you have a wealth of tools to do that yourself That's the problem. With Clojure you don't have to invent interfaces and then convince other libraries to use them. All the data structures are built upon well considered language level protocols that anyone can implement preventing pointless API proliferation.
  - postfuturist 14y ago
    yoklov, for some reason I can't reply directly. There are a few common lisp libraries of persistent, immutable data structures that perform well. This one is implemented most closely to Clojure's: https://github.com/ks/X.FDATATYPES https://github.com/ks/X.FDATATYPES . This one has been around for a long time and is quite stable: http://common-lisp.net/project/fset/Site/index.html http://common-lisp.net/project/fset/Site/index.html .
  - pjmlp 14y ago
    > Also above you said Clojure "probably" has better data structures than Common Lisp. That is unsubstantiated. It is my understanding that Common Lisp lacks the vector and hash maps that Clojure has. Sorry if I got it wrong. I am more a ML guy than Lisp.
    - mahmud 14y ago
      Your understanding continues to be wrong.
    - aidenn0 14y ago
      http://www.lispworks.com/documentation/HyperSpec/Body/t_vector.htm http://www.lispworks.com/documentation/HyperSpec/Body/t_vect... http://www.lispworks.com/documentation/HyperSpec/Body/t_hash_t.htm http://www.lispworks.com/documentation/HyperSpec/Body/t_hash...
      - pjmlp 14y ago
        I was wrong it seems. From the documentation I have not seen the simplified syntax Clojure uses for vectors, hashes and sets. I imagine that the syntax is Clojure specific.
- spacemanaki 14y ago
  edited bc mahmud said it better, but Also, Clojure supports (optional) dynamically scoped variables.

pjmlp 14y ago

> I don't fully grasp the advantages of being a Lisp-1 or Lisp-2 :) It has to do with variable scoping. Lisp-1 only accepts lexical scoping, while Lisp-2 also allows for dynamic scoping. http://www.nhplace.com/kent/Papers/Technical-Issues.html http://www.nhplace.com/kent/Papers/Technical-Issues.html

mahmud 14y ago
Good grief. No. Lisp-N has to do with the number of name spaces in the language. Lisp-1s only have ONE environment; the variables range over all values of the language, integers, functions, vectors, symbols, strings. In Lisp-N, there are N namespaces for each "kind" of value. Common Lisp is called a "Lisp-2" because it separates functions from other values. (it's closer to Lisp-5 or even Lisp-7, forgot which, because it allows that many kinds of "names" without collission. Also above you said Clojure "probably" has better data structures than Common Lisp. That is unsubstantiated.
- yoklov 14y ago
  For what it's worth, Clojure has implementations of Phil Bagwell's HAMT-based hash-maps, vectors, and sets. These are absolutely amazing data structures, and offer functional updates, a list-like API (O(log_32(n)) for most operations, which ends up being less than seven operations in practice, which is similar enough to O(1) for most programmers). I'm not much of a common lisp programmer (mostly sticking with scheme/racket and Clojure), but I don't think they've been ported to Common Lisp (yet), so the claim that Clojure has better data structures than Common Lisp, while somewhat a matter of preference, isn't entirely unsubstantiated.
  - mahmud 14y ago
    Common Lisp has hash-tables, vectors, and sets .. had it, in an ANSI-specified document since 1984. The implementation details of these is, well, implementation dependent, be they HAMT or whatever. The language provides a wealth of tools out of the box, but it's the job of the programmer to choose more appropriate tools for the problems at hand. The following is the Common Lisp specification. 12+ implementations, half of them industrial strength, more than half commercial vendors, and everyone of them has to adhere to this spec: http://www.franz.com/support/documentation/8.2/ansicl/ansicl.htm http://www.franz.com/support/documentation/8.2/ansicl/ansicl...
    - jules 14y ago
      Note that CL's data structures are mutable, whereas Clojure's are persistent.
      - swah 14y ago
        Google search saver: immutable = persistent
    - swannodette 14y ago
      But does Common Lisp allow multiple implementations of those data structures to exist in the same program actually allowing programmers to utilize the best tool for the job?
      - mahmud 14y ago
        Are you seriously asking me if a programming language allows for the implementation of data-structures? If you mean can users extend the core CL data-types, no, but you have a wealth of tools to do that yourself; use generic functions to implement whatever interface you wish, then provide for specific implementations.
        swannodette 14y ago
        but you have a wealth of tools to do that yourself That's the problem. With Clojure you don't have to invent interfaces and then convince other libraries to use them. All the data structures are built upon well considered language level protocols that anyone can implement preventing pointless API proliferation.
- postfuturist 14y ago
  yoklov, for some reason I can't reply directly. There are a few common lisp libraries of persistent, immutable data structures that perform well. This one is implemented most closely to Clojure's: https://github.com/ks/X.FDATATYPES https://github.com/ks/X.FDATATYPES . This one has been around for a long time and is quite stable: http://common-lisp.net/project/fset/Site/index.html http://common-lisp.net/project/fset/Site/index.html .
- pjmlp 14y ago
  > Also above you said Clojure "probably" has better data structures than Common Lisp. That is unsubstantiated. It is my understanding that Common Lisp lacks the vector and hash maps that Clojure has. Sorry if I got it wrong. I am more a ML guy than Lisp.
  - mahmud 14y ago
    Your understanding continues to be wrong.
  - aidenn0 14y ago
    http://www.lispworks.com/documentation/HyperSpec/Body/t_vector.htm http://www.lispworks.com/documentation/HyperSpec/Body/t_vect... http://www.lispworks.com/documentation/HyperSpec/Body/t_hash_t.htm http://www.lispworks.com/documentation/HyperSpec/Body/t_hash...
    - pjmlp 14y ago
      I was wrong it seems. From the documentation I have not seen the simplified syntax Clojure uses for vectors, hashes and sets. I imagine that the syntax is Clojure specific.
spacemanaki 14y ago
edited bc mahmud said it better, but Also, Clojure supports (optional) dynamically scoped variables.