5 ms·

Lisp will always be a special case. It's too powerful to give other languages a running. It's not quite the same when the language makes it ridiculously easy to

by jwdunne 10y ago

Lisp will always be a special case. It's too powerful to give other languages a running. It's not quite the same when the language makes it ridiculously easy to build new languages. What makes this impressive is the medium of expression, like when an artist blows you away with a Biro drawing. If someone wrote this in assembly in 500 lines or less (if that's even possible), it would be incredible.

dalke 10y ago
I have a different observation. This VM is meant to match Python semantics, including support for keyword arguments with defaults, lexical scope, and exceptions. Neither the original McCarthy Lisp description which qwertyuiop924 praised, nor first Lisp implementation by Russell, supported those features. The latter two features came with Lisp 1.5, whose implementations are much larger than 500 lines. http://www.softwarepreservation.org/projects/LISP http://www.softwarepreservation.org/projects/LISP . And that's okay - a language doesn't require those features. And a language without them, like Forth, can be much more compact as a result.
- nickpsecurity 10y ago
  I was curious so looked up McCarthy's paper. Appendix B has code and pseudo code for minimal interpreter. Takes one page. Primitives are easy to code, too. It would surpise me if that took much larger than 500loc to implement.
  - qwertyuiop924 10y ago
    Lexical scope, in particular, is very easy to implement. Call/cc or exceptions are a bit tougher, but it can be done. And all defaults take is a bit of extension to the lambda. In fact, defaults can be added atop the language with a macros, as can keyword arguments. Macro expanders are a bit harder to write than the functionality itself, however. Especially if you want a good one.
- qwertyuiop924 10y ago
  I wasn't intending to praise it, just show that other languages did similar things more elegantly. Also, in case you weren't reading carefully, I also pointed to Scheme's metacircular evaluator, which implements lexical scope, continuations (of which exceptions are a subset), and can implement defaults with relatively simple extension.
qwertyuiop924 10y ago
That's certainly true. It's a good point. It also means that if we're discussing the elegance with which a language can be expressed within itself, Lisp is a reasonable comparison to make, to show the maximum elegance with which this can be done.
- dalke 10y ago
  How do you judge that a Lisp implementation in Lisp is more elegant than a Forth implementation in Forth?
  - qwertyuiop924 10y ago
    I didn't say it was the only language that could implement itself elegantly. Admittedly, I've never seen seen a Forth implementation in Forth, so for all I know, it's incredibly ugly. Or so beautiful it could bring tears to the eyes of god. I don't know.
    - dalke 10y ago
      True, you didn't. But you did say it maximized elegance, which means you think a Forth in Forth cannot be more elegant. In practice, some people adore Forth. Most do not. Some people adore Prolog. Most do not. Relatively more people adore Lisp than either Forth or Prolog. Such elegance is therefore in the eye of the beholder, not some god. Forth's elegance is how it well it matches up to most hardware. The inner loop of a Forth interpreter can be as little as a few dozen lines of assembly, and its eval not much longer.
      - qwertyuiop924 10y ago
        True enough. shrug What did you expect me to do? Argue? You made some good points. :-D Although you do realize the god part was hyperbolic, showing an absurd maximal beauty. I'm not even very religious, it just seemed a fitting representation of such an absurd beauty. I thought that was pretty clear from the context...

by jwdunne 10y ago

dalke 10y ago

I have a different observation. This VM is meant to match Python semantics, including support for keyword arguments with defaults, lexical scope, and exceptions. Neither the original McCarthy Lisp description which qwertyuiop924 praised, nor first Lisp implementation by Russell, supported those features. The latter two features came with Lisp 1.5, whose implementations are much larger than 500 lines. http://www.softwarepreservation.org/projects/LISP http://www.softwarepreservation.org/projects/LISP . And that's okay - a language doesn't require those features. And a language without them, like Forth, can be much more compact as a result.

nickpsecurity 10y ago
I was curious so looked up McCarthy's paper. Appendix B has code and pseudo code for minimal interpreter. Takes one page. Primitives are easy to code, too. It would surpise me if that took much larger than 500loc to implement.
- qwertyuiop924 10y ago
  Lexical scope, in particular, is very easy to implement. Call/cc or exceptions are a bit tougher, but it can be done. And all defaults take is a bit of extension to the lambda. In fact, defaults can be added atop the language with a macros, as can keyword arguments. Macro expanders are a bit harder to write than the functionality itself, however. Especially if you want a good one.
qwertyuiop924 10y ago
I wasn't intending to praise it, just show that other languages did similar things more elegantly. Also, in case you weren't reading carefully, I also pointed to Scheme's metacircular evaluator, which implements lexical scope, continuations (of which exceptions are a subset), and can implement defaults with relatively simple extension.

qwertyuiop924 10y ago

That's certainly true. It's a good point. It also means that if we're discussing the elegance with which a language can be expressed within itself, Lisp is a reasonable comparison to make, to show the maximum elegance with which this can be done.

dalke 10y ago
How do you judge that a Lisp implementation in Lisp is more elegant than a Forth implementation in Forth?
- qwertyuiop924 10y ago
  I didn't say it was the only language that could implement itself elegantly. Admittedly, I've never seen seen a Forth implementation in Forth, so for all I know, it's incredibly ugly. Or so beautiful it could bring tears to the eyes of god. I don't know.
  - dalke 10y ago
    True, you didn't. But you did say it maximized elegance, which means you think a Forth in Forth cannot be more elegant. In practice, some people adore Forth. Most do not. Some people adore Prolog. Most do not. Relatively more people adore Lisp than either Forth or Prolog. Such elegance is therefore in the eye of the beholder, not some god. Forth's elegance is how it well it matches up to most hardware. The inner loop of a Forth interpreter can be as little as a few dozen lines of assembly, and its eval not much longer.
    - qwertyuiop924 10y ago
      True enough. shrug What did you expect me to do? Argue? You made some good points. :-D Although you do realize the god part was hyperbolic, showing an absurd maximal beauty. I'm not even very religious, it just seemed a fitting representation of such an absurd beauty. I thought that was pretty clear from the context...