3
    ];
  }
  ```

- Introduction of `--regex` and `--all` in `nix profile remove` and `nix profile upgrade` [#10166](https://github.com/NixOS/nix/pull/10166)

  Previously the command-line arguments for `nix profile remove` and `nix profile upgrade` matched the package entries using regular expression.
  For instance:

  ```
  nix profile remove '.*vim.*'
  ```

  This would remove all packages that contain `vim` in their name.

  In most cases, only singular package names were used to remove and upgrade packages. Mixing this with regular expressions sometimes lead to unintended behavior. For instance, `python3.1` could match `python311`.

  To avoid unintended behavior, the arguments are now only matching exact names.

  Matching using regular expressions is still possible by using the new `--regex` flag:

  ```
  nix profile remove --regex '.*vim.*'
  ```

  One of the most useful cases for using regular expressions was to upgrade all packages. This was previously accomplished by:

  ```
  nix profile upgrade '.*'
  ```

  With the introduction of the `--all` flag, this now becomes more straightforward:

  ```
  nix profile upgrade --all
  ```

- Visual clutter in `--debugger` is reduced [#9919](https://github.com/NixOS/nix/pull/9919)

  Before:
  ```
  info: breakpoint reached


  Starting REPL to allow you to inspect the current state of the evaluator.

  Welcome to Nix 2.20.0pre20231222_dirty. Type :? for help.

  nix-repl> :continue
  error: uh oh


  Starting REPL to allow you to inspect the current state of the evaluator.

  Welcome to Nix 2.20.0pre20231222_dirty. Type :? for help.

  nix-repl>
  ```

  After:

  ```
  info: breakpoint reached

  Nix 2.20.0pre20231222_dirty debugger
  Type :? for help.
  nix-repl> :continue
  error: uh oh

  nix-repl>
  ```

- Cycle detection in `nix repl` is simpler and more reliable [#8672](https://github.com/NixOS/nix/issues/8672) [#9926](https://github.com/NixOS/nix/pull/9926)

  The cycle detection in `nix repl`, `nix eval`, `builtins.trace`, and everywhere
  else values are printed is now simpler and matches the cycle detection in
  `nix-instantiate --eval` output.

  Before:

  ```
  nix eval --expr 'let self = { inherit self; }; in self'
  { self = { self = «repeated»; }; }
  ```

  After:

  ```
  { self = «repeated»; }
  ```

- In the debugger, `while evaluating the attribute` errors now include position information [#9915](https://github.com/NixOS/nix/pull/9915)

  Before:

  ```
  0: while evaluating the attribute 'python311.pythonForBuild.pkgs'
  0x600001522598
  ```

  After:

  ```
  0: while evaluating the attribute 'python311.pythonForBuild.pkgs'
  /nix/store/hg65h51xnp74ikahns9hyf3py5mlbbqq-source/overrides/default.nix:132:27

     131|
     132|       bootstrappingBase = pkgs.${self.python.pythonAttr}.pythonForBuild.pkgs;
        |                           ^
     133|     in
  ```

- Stack size is increased on macOS [#9860](https://github.com/NixOS/nix/pull/9860)

  Previously, Nix would set the stack size to 64MiB on Linux, but would leave the
  stack size set to the default (approximately 8KiB) on macOS. Now, the stack
  size is correctly set to 64MiB on macOS as well, which should reduce stack
  overflow segfaults in deeply-recursive Nix expressions.