Record · corpus.blog/posts/01a08789-803c-7129-942f-6f850f41d369

Object Soup is Made of Indexes

jacko.io · published 23 October 2023

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https://www.youtube.com/watch?v=lO1z-7cuRYI&t=1302

youtube.com

https://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html

doc.rust-lang.org

https://godbolt.org/

godbolt.org

http://docs.python.org/reference/datamodel.html

docs.python.org

https://openjdk.org/jeps/421

openjdk.org

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=struct+Person+%7B%0A++++name%3A+String%2C%0A++++friends%3A+Vec%3CPerson%3E%2C%0A%7D%0A%0Aimpl+Person+%7B%0A++++fn+new%28name%3A+%26str%29+-%3E+Person+%7B%0A++++++++Person+%7B+name%3A+name.into%28%29%2C+friends%3A+Vec%3A%3Anew%28%29+%7D%0A++++%7D%0A%0A++++fn+add_friend%28%26mut+self%2C+other%3A+Person%29+%7B%0A++++++++self.friends.push%28other%29%3B%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+mut+alice+%3D+Person%3A%3Anew%28%22Alice%22%29%3B%0A++++let+mut+bob+%3D+Person%3A%3Anew%28%22Bob%22%29%3B%0A++++alice.add_friend%28bob%29%3B%0A++++bob.add_friend%28alice%29%3B+%2F%2F+error%3A+borrow+of+moved+value%3A+%60bob%60%0A%7D

play.rust-lang.org

https://doc.rust-lang.org/book/ch04-01-what-is-ownership.html

doc.rust-lang.org

https://www.youtube.com/watch?v=IPmRDS0OSxM&t=3020

youtube.com

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=%23%5Bderive%28Clone%29%5D%0Astruct+Person+%7B%0A++++_name%3A+String%2C%0A++++friends%3A+Vec%3CPerson%3E%2C%0A%7D%0A%0Aimpl+Person+%7B%0A++++fn+new%28name%3A+%26str%29+-%3E+Person+%7B%0A++++++++Person+%7B+_name%3A+name.into%28%29%2C+friends%3A+Vec%3A%3Anew%28%29+%7D%0A++++%7D%0A%0A++++fn+add_friend%28%26mut+self%2C+other%3A+Person%29+%7B%0A++++++++self.friends.push%28other%29%3B%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+mut+alice+%3D+Person%3A%3Anew%28%22Alice%22%29%3B%0A++++let+mut+bob+%3D+Person%3A%3Anew%28%22Bob%22%29%3B%0A++++alice.add_friend%28bob.clone%28%29%29%3B%0A++++bob.add_friend%28alice.clone%28%29%29%3B%0A%7D

play.rust-lang.org

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play.rust-lang.org

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=struct+Person%3C%27friends%3E+%7B%0A++++name%3A+String%2C%0A++++friends%3A+Vec%3C%26%27friends+mut+Person%3C%27friends%3E%3E%2C%0A%7D%0A%0Aimpl%3C%27friends%3E+Person%3C%27friends%3E+%7B%0A++++fn+new%28name%3A+%26str%29+-%3E+Person%3C%27friends%3E+%7B%0A++++++++Person+%7B+name%3A+name.into%28%29%2C+friends%3A+Vec%3A%3Anew%28%29+%7D%0A++++%7D%0A%0A++++fn+add_friend%28%26mut+self%2C+other%3A+%26%27friends+mut+Person%3C%27friends%3E%29+%7B%0A++++++++self.friends.push%28other%29%3B%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+mut+alice+%3D+Person%3A%3Anew%28%22Alice%22%29%3B%0A++++let+mut+bob+%3D+Person%3A%3Anew%28%22Bob%22%29%3B%0A++++alice.add_friend%28%26mut+bob%29%3B%0A++++alice.friends%5B0%5D.add_friend%28%26mut+alice%29%3B%0A%7D%0A

play.rust-lang.org

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=use+std%3A%3Acell%3A%3ARefCell%3B%0A%0Astruct+Person%3C%27friends%3E+%7B%0A++++_name%3A+String%2C%0A++++friends%3A+RefCell%3CVec%3C%26%27friends+Person%3C%27friends%3E%3E%3E%2C%0A%7D%0A%0Aimpl%3C%27friends%3E+Person%3C%27friends%3E+%7B%0A++++fn+new%28name%3A+%26str%29+-%3E+Person%3C%27friends%3E+%7B%0A++++++++Person+%7B+_name%3A+name.into%28%29%2C+friends%3A+RefCell%3A%3Anew%28Vec%3A%3Anew%28%29%29+%7D%0A++++%7D%0A%0A++++fn+add_friend%28%26self%2C+other%3A+%26%27friends+Person%3C%27friends%3E%29+%7B%0A++++++++self.friends.borrow_mut%28%29.push%28other%29%3B%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+alice+%3D+Person%3A%3Anew%28%22Alice%22%29%3B%0A++++let+bob+%3D+Person%3A%3Anew%28%22Bob%22%29%3B%0A++++alice.add_friend%28%26bob%29%3B%0A++++bob.add_friend%28%26alice%29%3B%0A%7D

play.rust-lang.org

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=use+std%3A%3Acell%3A%3ARefCell%3B%0A%0Astruct+Person%3C%27friends%3E+%7B%0A++++name%3A+String%2C%0A++++friends%3A+RefCell%3CVec%3C%26%27friends+Person%3C%27friends%3E%3E%3E%2C%0A%7D%0A%0Aimpl%3C%27friends%3E+Person%3C%27friends%3E+%7B%0A++++fn+new%28name%3A+%26str%29+-%3E+Person%3C%27friends%3E+%7B%0A++++++++Person+%7B+name%3A+name.into%28%29%2C+friends%3A+RefCell%3A%3Anew%28Vec%3A%3Anew%28%29%29+%7D%0A++++%7D%0A%0A++++fn+add_friend%28%26self%2C+other%3A+%26%27friends+Person%3C%27friends%3E%29+%7B%0A++++++++self.friends.borrow_mut%28%29.push%28other%29%3B%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+alice+%3D+Person%3A%3Anew%28%22Alice%22%29%3B%0A++++let+bob+%3D+Person%3A%3Anew%28%22Bob%22%29%3B%0A++++alice.add_friend%28%26bob%29%3B%0A++++bob.add_friend%28%26alice%29%3B%0A++++vec%21%5Balice%2C+bob%5D%3B%0A%7D

play.rust-lang.org

https://doc.rust-lang.org/std/rc/struct.Rc.html

doc.rust-lang.org

https://en.wikipedia.org/wiki/Reference_counting

en.wikipedia.org

https://doc.rust-lang.org/std/cell/struct.RefCell.html

doc.rust-lang.org

https://doc.rust-lang.org/stable/std/sync/struct.RwLock.html

doc.rust-lang.org

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=use+std%3A%3Acell%3A%3ARefCell%3B%0Ause+std%3A%3Arc%3A%3ARc%3B%0A%0Astruct+Person+%7B%0A++++_name%3A+String%2C%0A++++friends%3A+Vec%3CRc%3CRefCell%3CPerson%3E%3E%3E%2C%0A%7D%0A%0Aimpl+Person+%7B%0A++++fn+new%28name%3A+%26str%29+-%3E+Person+%7B%0A++++++++Person+%7B+_name%3A+name.into%28%29%2C+friends%3A+Vec%3A%3Anew%28%29+%7D%0A++++%7D%0A%0A++++fn+add_friend%28%26mut+self%2C+other%3A+Rc%3CRefCell%3CPerson%3E%3E%29+%7B%0A++++++++self.friends.push%28other%29%3B%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+alice+%3D+Rc%3A%3Anew%28RefCell%3A%3Anew%28Person%3A%3Anew%28%22Alice%22%29%29%29%3B%0A++++let+bob+%3D+Rc%3A%3Anew%28RefCell%3A%3Anew%28Person%3A%3Anew%28%22Bob%22%29%29%29%3B%0A++++alice.borrow_mut%28%29.add_friend%28Rc%3A%3Aclone%28%26bob%29%29%3B%0A++++bob.borrow_mut%28%29.add_friend%28Rc%3A%3Aclone%28%26alice%29%29%3B%0A%0A++++%2F%2F+Rc%3A%3Aclone+creates+a+new+Rc+pointing+to+the+same+shared+object.+Any%0A++++%2F%2F+changes+we+make+to+the+original+are+visible+through+the+new+Rc.%0A++++let+bob_ref+%3D+%26alice.borrow%28%29.friends%5B0%5D%3B%0A++++assert_eq%21%28bob_ref.borrow%28%29.friends.len%28%29%2C+1%29%3B%0A%7D

play.rust-lang.org

https://doc.rust-lang.org/book/ch15-00-smart-pointers.html

doc.rust-lang.org

https://doc.rust-lang.org/std/cell/struct.RefMut.html

doc.rust-lang.org

https://doc.rust-lang.org/std/ops/trait.Deref.html

doc.rust-lang.org

https://doc.rust-lang.org/std/ops/trait.DerefMut.html

doc.rust-lang.org

https://doc.rust-lang.org/book/ch15-02-deref.html

doc.rust-lang.org

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=use+std%3A%3Acell%3A%3A%7BRefCell%2C+RefMut%7D%3B%0Ause+std%3A%3Aops%3A%3A%7BDeref%2C+DerefMut%7D%3B%0Ause+std%3A%3Arc%3A%3ARc%3B%0A%0Astruct+Person+%7B%0A++++_name%3A+String%2C%0A++++friends%3A+Vec%3CRc%3CRefCell%3CPerson%3E%3E%3E%2C%0A%7D%0A%0Aimpl+Person+%7B%0A++++fn+new%28name%3A+%26str%29+-%3E+Person+%7B%0A++++++++Person+%7B+_name%3A+name.into%28%29%2C+friends%3A+Vec%3A%3Anew%28%29+%7D%0A++++%7D%0A%0A++++fn+add_friend%28%26mut+self%2C+other%3A+Rc%3CRefCell%3CPerson%3E%3E%29+%7B%0A++++++++self.friends.push%28other%29%3B%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+alice+%3D+Rc%3A%3Anew%28RefCell%3A%3Anew%28Person%3A%3Anew%28%22Alice%22%29%29%29%3B%0A++++let+bob+%3D+Rc%3A%3Anew%28RefCell%3A%3Anew%28Person%3A%3Anew%28%22Bob%22%29%29%29%3B%0A%0A++++%2F%2F+alice.borrow_mut%28%29.add_friend%28Rc%3A%3Aclone%28%26bob%29%29%3B%0A++++let+alice_refcell%3A++++%26RefCell%3CPerson%3E++++%3D+alice.deref%28%29%3B%0A++++let+mut+alice_refmut%3A+RefMut%3CPerson%3E++++++%3D+alice_refcell.borrow_mut%28%29%3B%0A++++let+alice_mut%3A++++++++%26mut+Person+++++++++%3D+alice_refmut.deref_mut%28%29%3B%0A++++let+bob_alias%3A++++++++Rc%3CRefCell%3CPerson%3E%3E+%3D+Rc%3A%3Aclone%28%26bob%29%3B%0A++++alice_mut.add_friend%28bob_alias%29%3B%0A++++drop%28alice_refmut%29%3B%0A%0A++++%2F%2F+bob.borrow_mut%28%29.add_friend%28Rc%3A%3Aclone%28%26alice%29%29%3B%0A++++let+bob_refcell%3A++++%26RefCell%3CPerson%3E++++%3D+bob.deref%28%29%3B%0A++++let+mut+bob_refmut%3A+RefMut%3CPerson%3E++++++%3D+bob_refcell.borrow_mut%28%29%3B%0A++++let+bob_mut%3A++++++++%26mut+Person+++++++++%3D+bob_refmut.deref_mut%28%29%3B%0A++++let+alice_alias%3A++++Rc%3CRefCell%3CPerson%3E%3E+%3D+Rc%3A%3Aclone%28%26alice%29%3B%0A++++bob_mut.add_friend%28alice_alias%29%3B%0A++++drop%28bob_refmut%29%3B%0A%7D

play.rust-lang.org

https://docs.python.org/3/library/gc.html

docs.python.org

play.rust-lang.org

https://www.kalzumeus.com/2010/06/17/falsehoods-programmers-believe-about-names/

kalzumeus.com

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=use+std%3A%3Acell%3A%3ARefCell%3B%0Ause+std%3A%3Arc%3A%3ARc%3B%0A%0Astruct+Person+%7B%0A++++name%3A+String%2C%0A++++friends%3A+Vec%3CRc%3CRefCell%3CPerson%3E%3E%3E%2C%0A%7D%0A%0Aimpl+Person+%7B%0A++++fn+new%28name%3A+%26str%29+-%3E+Person+%7B%0A++++++++Person+%7B+name%3A+name.into%28%29%2C+friends%3A+Vec%3A%3Anew%28%29+%7D%0A++++%7D%0A%0A++++fn+add_friend%28%26mut+self%2C+other%3A+%26Rc%3CRefCell%3CPerson%3E%3E%29+%7B%0A++++++++if+other.borrow%28%29.name+%21%3D+self.name+%7B%0A++++++++++++self.friends.push%28Rc%3A%3Aclone%28other%29%29%3B%0A++++++++%7D%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+alice+%3D+Rc%3A%3Anew%28RefCell%3A%3Anew%28Person%3A%3Anew%28%22Alice%22%29%29%29%3B%0A++++let+bob+%3D+Rc%3A%3Anew%28RefCell%3A%3Anew%28Person%3A%3Anew%28%22Bob%22%29%29%29%3B%0A++++alice.borrow_mut%28%29.add_friend%28%26bob%29%3B%0A++++bob.borrow_mut%28%29.add_friend%28%26alice%29%3B%0A%0A++++%2F%2F+Break+the+reference+cycle.%0A++++alice.borrow_mut%28%29.friends.clear%28%29%3B%0A%7D

play.rust-lang.org

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=use+std%3A%3Acell%3A%3ARefCell%3B%0Ause+std%3A%3Arc%3A%3ARc%3B%0A%0Astruct+Person+%7B%0A++++name%3A+String%2C%0A++++friends%3A+Vec%3CRc%3CRefCell%3CPerson%3E%3E%3E%2C%0A%7D%0A%0Aimpl+Person+%7B%0A++++fn+new%28name%3A+%26str%29+-%3E+Person+%7B%0A++++++++Person+%7B+name%3A+name.into%28%29%2C+friends%3A+Vec%3A%3Anew%28%29+%7D%0A++++%7D%0A%0A++++fn+add_friend%28%26mut+self%2C+other%3A+%26Rc%3CRefCell%3CPerson%3E%3E%29+%7B%0A++++++++if+other.borrow%28%29.name+%21%3D+self.name+%7B%0A++++++++++++self.friends.push%28Rc%3A%3Aclone%28other%29%29%3B%0A++++++++%7D%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+alice+%3D+Rc%3A%3Anew%28RefCell%3A%3Anew%28Person%3A%3Anew%28%22Alice%22%29%29%29%3B%0A++++let+bob+%3D+Rc%3A%3Anew%28RefCell%3A%3Anew%28Person%3A%3Anew%28%22Bob%22%29%29%29%3B%0A++++alice.borrow_mut%28%29.add_friend%28%26bob%29%3B%0A++++bob.borrow_mut%28%29.add_friend%28%26alice%29%3B%0A++++alice.borrow_mut%28%29.add_friend%28%26alice%29%3B++%2F%2F+panic%3A+already+mutably+borrowed%0A%7D

play.rust-lang.org

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=use+std%3A%3Async%3A%3A%7BArc%2C+RwLock%7D%3B%0A%0Astruct+Person+%7B%0A++++name%3A+String%2C%0A++++friends%3A+Vec%3CArc%3CRwLock%3CPerson%3E%3E%3E%2C%0A%7D%0A%0Aimpl+Person+%7B%0A++++fn+new%28name%3A+%26str%29+-%3E+Person+%7B%0A++++++++Person+%7B+name%3A+name.into%28%29%2C+friends%3A+Vec%3A%3Anew%28%29+%7D%0A++++%7D%0A%0A++++fn+add_friend%28%26mut+self%2C+other%3A+%26Arc%3CRwLock%3CPerson%3E%3E%29+%7B%0A++++++++if+other.read%28%29.unwrap%28%29.name+%21%3D+self.name+%7B%0A++++++++++++self.friends.push%28Arc%3A%3Aclone%28other%29%29%3B%0A++++++++%7D%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+alice+%3D+Arc%3A%3Anew%28RwLock%3A%3Anew%28Person%3A%3Anew%28%22Alice%22%29%29%29%3B%0A++++let+bob+%3D+Arc%3A%3Anew%28RwLock%3A%3Anew%28Person%3A%3Anew%28%22Bob%22%29%29%29%3B%0A++++alice.write%28%29.unwrap%28%29.add_friend%28%26bob%29%3B%0A++++bob.write%28%29.unwrap%28%29.add_friend%28%26alice%29%3B%0A%0A++++println%21%28%22This+is+going+to+deadlock...%22%29%3B%0A++++alice.write%28%29.unwrap%28%29.add_friend%28%26alice%29%3B%0A++++println%21%28%22We+never+make+it+here%21%22%29%3B%0A%7D

play.rust-lang.org

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=use+std%3A%3Acell%3A%3ARefCell%3B%0Ause+std%3A%3Arc%3A%3ARc%3B%0A%0Astruct+Person+%7B%0A++++name%3A+String%2C%0A++++friends%3A+Vec%3CRc%3CRefCell%3CPerson%3E%3E%3E%2C%0A%7D%0A%0Aimpl+Person+%7B%0A++++fn+new%28name%3A+%26str%29+-%3E+Person+%7B%0A++++++++Person+%7B+name%3A+name.into%28%29%2C+friends%3A+Vec%3A%3Anew%28%29+%7D%0A++++%7D%0A%7D%0A%0Afn+add_friend%28this%3A+%26Rc%3CRefCell%3CPerson%3E%3E%2C+other%3A+%26Rc%3CRefCell%3CPerson%3E%3E%29+%7B%0A++++if+other.borrow%28%29.name+%21%3D+this.borrow%28%29.name+%7B%0A++++++++this.borrow_mut%28%29.friends.push%28Rc%3A%3Aclone%28other%29%29%3B%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+alice+%3D+Rc%3A%3Anew%28RefCell%3A%3Anew%28Person%3A%3Anew%28%22Alice%22%29%29%29%3B%0A++++let+bob+%3D+Rc%3A%3Anew%28RefCell%3A%3Anew%28Person%3A%3Anew%28%22Bob%22%29%29%29%3B%0A++++add_friend%28%26alice%2C+%26bob%29%3B%0A++++add_friend%28%26bob%2C+%26alice%29%3B%0A++++add_friend%28%26alice%2C+%26alice%29%3B%0A%0A++++%2F%2F+Break+the+reference+cycle.%0A++++alice.borrow_mut%28%29.friends.clear%28%29%3B%0A%7D

play.rust-lang.org

https://www.youtube.com/watch?v=DG-VLezRkYQ

youtube.com

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=struct+Person+%7B%0A++++name%3A+String%2C%0A++++friends%3A+Vec%3Cusize%3E%2C%0A%7D%0A%0Afn+new_person%28people%3A+%26mut+Vec%3CPerson%3E%2C+name%3A+%26str%29+-%3E+usize+%7B%0A++++people.push%28Person+%7B+name%3A+name.into%28%29%2C+friends%3A+Vec%3A%3Anew%28%29+%7D%29%3B%0A++++people.len%28%29+-+1%0A%7D%0A%0Afn+add_friend%28people%3A+%26mut+Vec%3CPerson%3E%2C+this_id%3A+usize%2C+other_id%3A+usize%29+%7B%0A++++if+people%5Bother_id%5D.name+%21%3D+people%5Bthis_id%5D.name+%7B%0A++++++++people%5Bthis_id%5D.friends.push%28other_id%29%3B%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+mut+people+%3D+Vec%3A%3Anew%28%29%3B%0A++++let+alice_id+%3D+new_person%28%26mut+people%2C+%22Alice%22%29%3B%0A++++let+bob_id+%3D+new_person%28%26mut+people%2C+%22Bob%22%29%3B%0A++++add_friend%28%26mut+people%2C+alice_id%2C+bob_id%29%3B%0A++++add_friend%28%26mut+people%2C+bob_id%2C+alice_id%29%3B%0A++++add_friend%28%26mut+people%2C+alice_id%2C+alice_id%29%3B+%2F%2F+no-op%0A%7D

play.rust-lang.org

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=struct+Person+%7B%0A++++name%3A+String%2C%0A++++friends%3A+Vec%3Cusize%3E%2C%0A%7D%0A%0Aimpl+Person+%7B%0A++++fn+new%28people%3A+%26mut+Vec%3CPerson%3E%2C+name%3A+%26str%29+-%3E+usize+%7B%0A++++++++people.push%28Person+%7B+name%3A+name.into%28%29%2C+friends%3A+Vec%3A%3Anew%28%29+%7D%29%3B%0A++++++++people.len%28%29+-+1%0A++++%7D%0A%0A++++%2F%2F+MISTAKE%3A+%60%26mut+self%60+methods+don%27t+work+well+in+code+like+this%2C+because%0A++++%2F%2F+we+need+to+refer+to+%60self%60+by+index+to+avoid+mutable+aliasing.+I%0A++++%2F%2F+should%27ve+made+this+a+standalone+function+instead.%0A++++fn+add_friend%28%26mut+self%2C+people%3A+%26Vec%3CPerson%3E%2C+other_id%3A+usize%29+%7B%0A++++++++if+people%5Bother_id%5D.name+%21%3D+self.name+%7B%0A++++++++++++self.friends.push%28other_id%29%3B%0A++++++++%7D%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+mut+people+%3D+Vec%3A%3Anew%28%29%3B%0A++++let+alice_id+%3D+Person%3A%3Anew%28%26mut+people%2C+%22Alice%22%29%3B%0A++++let+bob_id+%3D+Person%3A%3Anew%28%26mut+people%2C+%22Bob%22%29%3B%0A++++%2F%2F+These+lines+don%27t+compile%2C+because+we%27re+trying+to+borrow+the+entire+Vec%0A++++%2F%2F+while+we%27re+mutating+one+of+its+elements.%0A++++people%5Balice_id%5D.add_friend%28%26people%2C+bob_id%29%3B%0A++++people%5Bbob_id%5D.add_friend%28%26people%2C+alice_id%29%3B%0A++++people%5Balice_id%5D.add_friend%28%26people%2C+alice_id%29%3B%0A%7D

play.rust-lang.org

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=use+serde%3A%3ASerialize%3B%0A%0A%23%5Bderive%28Serialize%29%5D%0Astruct+Person+%7B%0A++++name%3A+String%2C%0A++++friends%3A+Vec%3Cusize%3E%2C%0A%7D%0A%0Afn+new_person%28people%3A+%26mut+Vec%3CPerson%3E%2C+name%3A+%26str%29+-%3E+usize+%7B%0A++++people.push%28Person+%7B+name%3A+name.into%28%29%2C+friends%3A+Vec%3A%3Anew%28%29+%7D%29%3B%0A++++people.len%28%29+-+1%0A%7D%0A%0Afn+add_friend%28people%3A+%26mut+Vec%3CPerson%3E%2C+this_id%3A+usize%2C+other_id%3A+usize%29+%7B%0A++++if+people%5Bother_id%5D.name+%21%3D+people%5Bthis_id%5D.name+%7B%0A++++++++people%5Bthis_id%5D.friends.push%28other_id%29%3B%0A++++%7D%0A%7D%0A%0Afn+main%28%29+-%3E+anyhow%3A%3AResult%3C%28%29%3E+%7B%0A++++let+mut+people+%3D+Vec%3A%3Anew%28%29%3B%0A++++let+alice_id+%3D+new_person%28%26mut+people%2C+%22Alice%22%29%3B%0A++++let+bob_id+%3D+new_person%28%26mut+people%2C+%22Bob%22%29%3B%0A++++add_friend%28%26mut+people%2C+alice_id%2C+bob_id%29%3B%0A++++add_friend%28%26mut+people%2C+bob_id%2C+alice_id%29%3B%0A++++add_friend%28%26mut+people%2C+alice_id%2C+alice_id%29%3B+%2F%2F+no-op%0A%0A++++%2F%2F+Serialize+the+people+Vec+into+a+JSON+string.%0A++++let+json+%3D+serde_json%3A%3Ato_string_pretty%28%26people%29%3F%3B%0A++++println%21%28%22%7B%7D%22%2C+json%29%3B%0A%0A++++Ok%28%28%29%29%0A%7D

play.rust-lang.org

https://serde.rs/feature-flags.html

serde.rs

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=use+std%3A%3Acell%3A%3ARefCell%3B%0Ause+std%3A%3Arc%3A%3ARc%3B%0Ause+serde%3A%3ASerialize%3B%0A%0A%23%5Bderive%28Serialize%29%5D%0Astruct+Person+%7B%0A++++_name%3A+String%2C%0A++++friends%3A+Vec%3CRc%3CRefCell%3CPerson%3E%3E%3E%2C%0A%7D%0A%0Aimpl+Person+%7B%0A++++fn+new%28name%3A+%26str%29+-%3E+Person+%7B%0A++++++++Person+%7B+_name%3A+name.into%28%29%2C+friends%3A+Vec%3A%3Anew%28%29+%7D%0A++++%7D%0A%0A++++fn+add_friend%28%26mut+self%2C+other%3A+Rc%3CRefCell%3CPerson%3E%3E%29+%7B%0A++++++++self.friends.push%28other%29%3B%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+alice+%3D+Rc%3A%3Anew%28RefCell%3A%3Anew%28Person%3A%3Anew%28%22Alice%22%29%29%29%3B%0A++++let+bob+%3D+Rc%3A%3Anew%28RefCell%3A%3Anew%28Person%3A%3Anew%28%22Bob%22%29%29%29%3B%0A++++alice.borrow_mut%28%29.add_friend%28Rc%3A%3Aclone%28%26bob%29%29%3B%0A++++bob.borrow_mut%28%29.add_friend%28Rc%3A%3Aclone%28%26alice%29%29%3B%0A%0A++++serde_json%3A%3Ato_string%28%26alice%29.unwrap%28%29%3B+%2F%2F+panic%3A+stack+overflow%0A%7D

play.rust-lang.org

https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&code=use+rayon%3A%3Aprelude%3A%3A*%3B%0Ause+std%3A%3Athread%3A%3Asleep%3B%0Ause+std%3A%3Atime%3A%3A%7BDuration%2C+Instant%7D%3B%0A%0Astruct+Person+%7B%0A++++name%3A+String%2C%0A++++friends%3A+Vec%3Cusize%3E%2C%0A%7D%0A%0Afn+new_person%28people%3A+%26mut+Vec%3CPerson%3E%2C+name%3A+%26str%29+-%3E+usize+%7B%0A++++people.push%28Person+%7B+name%3A+name.into%28%29%2C+friends%3A+Vec%3A%3Anew%28%29+%7D%29%3B%0A++++people.len%28%29+-+1%0A%7D%0A%0Afn+add_friend%28people%3A+%26mut+Vec%3CPerson%3E%2C+this_id%3A+usize%2C+other_id%3A+usize%29+%7B%0A++++if+people%5Bother_id%5D.name+%21%3D+people%5Bthis_id%5D.name+%7B%0A++++++++people%5Bthis_id%5D.friends.push%28other_id%29%3B%0A++++%7D%0A%7D%0A%0Afn+main%28%29+%7B%0A++++let+mut+people+%3D+Vec%3A%3Anew%28%29%3B%0A++++let+alice_id+%3D+new_person%28%26mut+people%2C+%22Alice%22%29%3B%0A++++let+bob_id+%3D+new_person%28%26mut+people%2C+%22Bob%22%29%3B%0A++++add_friend%28%26mut+people%2C+alice_id%2C+bob_id%29%3B%0A++++add_friend%28%26mut+people%2C+bob_id%2C+alice_id%29%3B%0A++++add_friend%28%26mut+people%2C+alice_id%2C+alice_id%29%3B+%2F%2F+no-op%0A%0A++++%2F%2F+Iterate+over+the+people+Vec+using+multiple+threads.+We+sleep+1+second+for%0A++++%2F%2F+each+person%2C+so+if+this+were+a+single-threaded+loop+it+would+take+2%0A++++%2F%2F+seconds.+But+because+it%27s+multithreaded%2C+it+only+takes+1+second.%0A++++let+start+%3D+Instant%3A%3Anow%28%29%3B%0A++++people.par_iter%28%29.for_each%28%7Cperson%7C+%7B%0A++++++++sleep%28Duration%3A%3Afrom_secs%281%29%29%3B%0A++++++++println%21%28%22%7B%7D%22%2C+person.name%29%3B%0A++++%7D%29%3B%0A++++println%21%28%22Total+time%3A+%7B%3A%3F%7D%22%2C+Instant%3A%3Anow%28%29.duration_since%28start%29%29%3B%0A%7D

play.rust-lang.org

https://docs.rs/uuid

docs.rs

https://docs.rs/slab

docs.rs

https://docs.rs/slotmap/

docs.rs

https://www.youtube.com/watch?v=aKLntZcp27M

youtube.com

https://www.reddit.com/r/rust/comments/17ehphv/object_soup_is_made_of_indexes/?

reddit.com

https://news.ycombinator.com/item?id=37983998

news.ycombinator.com

https://lobste.rs/s/zhbv0i/object_soup_is_made_indexes_rust

lobste.rs