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years ago someone posted http://norvig.com/lispy.html http://norvig.com/lispy.html here on HN I wrote a lisp in C# based on that, it was only a 100+ ish lines

years ago someone posted http://norvig.com/lispy.html http://norvig.com/lispy.html here on HN I wrote a lisp in C# based on that, it was only a 100+ ish lines of code. It was a great way to get into Lisp.

codr7 2y ago
Yes, I am aware. I started out designing Forth interpreters, actually calculators and template engines, but Forth was a natural progression. My design differs a lot from idiomatic Lisp implementations (likewise Forth), and I do sometimes wonder what it would look like if you started in that end and worked your way towards supporting all the features of sharpl.
- codr7 2y ago
  Having thought a bit about it, one motivation for choosing the route I did; rather than the more idiomatic one; is that it relies on pipeline of source transformations to get to optimal code. The initial expansion is often pretty sloppy. I don't do many source transformations, everything is designed to emit pretty optimal byte code on the first pass.
dualogy 2y ago
There's also Make-A-Lisp and, unlike most write-you-a-lisp/scheme-s out there, that one also covers TCO interpretation, quasiquotation/unquote for macros and their expansion, and goes up to self-hosting: https://github.com/kanaka/mal/ https://github.com/kanaka/mal/ I just went through it over 2-3 days, great practice IMHO to do once in your life from start to finish: https://github.com/metaleap/go-lisp https://github.com/metaleap/go-lisp
- KineticLensman 2y ago
  Concur, although it took me two to three months, not days (was working full time is my excuse). Biggest grief point was getting macro expansion to work correctly; TCO worked almost first time, IIRC.
  - codr7 2y ago
    Unquoting took me several implementations to wrap my head around and consistently get good enough. As did register allocation, which is more of a VM issue.
    - KineticLensman 2y ago
      Interesting. I'm about to start doing a MAL-like again, but this time (I used C# before) using Rust and building a VM as in Crafting Interpreters rather than following the MAL guide. Macros are one of the things that I anticipate being a challenge.
      - dualogy 2y ago
        AFAICT, their expansion still happens during an interpretation cycle — but when you "interpret" AST into your byte-code.
        codr7 2y ago
        Or compile, since it's usually a transformation. I like to call that the emit phase, as in emitting byte code. The interesting thing is that it only happens once, before the code is evaluated.

codr7 2y ago

Yes, I am aware. I started out designing Forth interpreters, actually calculators and template engines, but Forth was a natural progression. My design differs a lot from idiomatic Lisp implementations (likewise Forth), and I do sometimes wonder what it would look like if you started in that end and worked your way towards supporting all the features of sharpl.

codr7 2y ago
Having thought a bit about it, one motivation for choosing the route I did; rather than the more idiomatic one; is that it relies on pipeline of source transformations to get to optimal code. The initial expansion is often pretty sloppy. I don't do many source transformations, everything is designed to emit pretty optimal byte code on the first pass.

dualogy 2y ago

There's also Make-A-Lisp and, unlike most write-you-a-lisp/scheme-s out there, that one also covers TCO interpretation, quasiquotation/unquote for macros and their expansion, and goes up to self-hosting: https://github.com/kanaka/mal/ https://github.com/kanaka/mal/ I just went through it over 2-3 days, great practice IMHO to do once in your life from start to finish: https://github.com/metaleap/go-lisp https://github.com/metaleap/go-lisp

KineticLensman 2y ago
Concur, although it took me two to three months, not days (was working full time is my excuse). Biggest grief point was getting macro expansion to work correctly; TCO worked almost first time, IIRC.
- codr7 2y ago
  Unquoting took me several implementations to wrap my head around and consistently get good enough. As did register allocation, which is more of a VM issue.
  - KineticLensman 2y ago
    Interesting. I'm about to start doing a MAL-like again, but this time (I used C# before) using Rust and building a VM as in Crafting Interpreters rather than following the MAL guide. Macros are one of the things that I anticipate being a challenge.
    - dualogy 2y ago
      AFAICT, their expansion still happens during an interpretation cycle — but when you "interpret" AST into your byte-code.
      - codr7 2y ago
        Or compile, since it's usually a transformation. I like to call that the emit phase, as in emitting byte code. The interesting thing is that it only happens once, before the code is evaluated.