5 ms·

I don't know about Linear Lisp, but if you do linear types as in Wadler's "Linear Types Can Change the World"[0] then the absence of the call to free would be a

I don't know about Linear Lisp, but if you do linear types as in Wadler's "Linear Types Can Change the World"[0] then the absence of the call to free would be a compilation error. [0] https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.31.5002&rep=rep1&type=pdf https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.31...

ithkuil 4y ago
Why not inserting a call to free automatically instead of forcing you to do it manually?
- southerntofu 4y ago
  Isn't that exactly why Rust needs lifetime annotation and Drop trait implementations? How could you achieve the same result without that, or without a garbage collector alternatively?
  - shirleyquirk 4y ago
    You'd use automatic reference counting, as Swift and Nim do.
    - southerntofu 4y ago
      Good point! I had previously assumed this was considered a form of "garbage collector" although not tracing.
      - j-james 4y ago
        Well, sort of - it adds overhead, though in the form of an extra byte/object and an extra CPU cycle when objects are allocated/deallocated to check/update the reference counts, rather than the lag spikes tracing GCs are known for.
- whateveracct 4y ago
  1. When you call free matters - it does something after all! 2. You can build abstractions that call free for you. The common withX callback-style function can be better typed with linear types and call free for you, for instance.
  - ithkuil 4y ago
    2 would be a kind of explicit destructors/drop ?
    - pjmlp 4y ago
      Something like this fictional language, with-some-resource { res -> // use res as you like } The with-some-resource function takes care of the resource management, while the type system takes care res doesn't escape the lambda.
      - ithkuil 4y ago
        What if you want to move the ownership of the resource and let the new owner eventually to dispose it?
        whateveracct 4y ago
        Then withX isn't the right abstraction. The original situation (malloc gives you a linear variable) handles what you want. A function that takes the variable but does not return it effectively "takes ownership of it" and the type system will force a free. There's a "Linear Constraints" paper draft out there that emulates ownership and borrowing with linear types, and uses the titular new language feature to greatly improve ergonomics.

ithkuil 4y ago

Why not inserting a call to free automatically instead of forcing you to do it manually?

southerntofu 4y ago
Isn't that exactly why Rust needs lifetime annotation and Drop trait implementations? How could you achieve the same result without that, or without a garbage collector alternatively?
- shirleyquirk 4y ago
  You'd use automatic reference counting, as Swift and Nim do.
  - southerntofu 4y ago
    Good point! I had previously assumed this was considered a form of "garbage collector" although not tracing.
    - j-james 4y ago
      Well, sort of - it adds overhead, though in the form of an extra byte/object and an extra CPU cycle when objects are allocated/deallocated to check/update the reference counts, rather than the lag spikes tracing GCs are known for.
whateveracct 4y ago
1. When you call free matters - it does something after all! 2. You can build abstractions that call free for you. The common withX callback-style function can be better typed with linear types and call free for you, for instance.
- ithkuil 4y ago
  2 would be a kind of explicit destructors/drop ?
  - pjmlp 4y ago
    Something like this fictional language, with-some-resource { res -> // use res as you like } The with-some-resource function takes care of the resource management, while the type system takes care res doesn't escape the lambda.
    - ithkuil 4y ago
      What if you want to move the ownership of the resource and let the new owner eventually to dispose it?
      - whateveracct 4y ago
        Then withX isn't the right abstraction. The original situation (malloc gives you a linear variable) handles what you want. A function that takes the variable but does not return it effectively "takes ownership of it" and the type system will force a free. There's a "Linear Constraints" paper draft out there that emulates ownership and borrowing with linear types, and uses the titular new language feature to greatly improve ergonomics.