elan vs plenv

elan manages installations of the Lean theorem prover on Linux, macOS and Windows. Its `lean` and `lake` binaries use a project’s `lean-toolchain` file to select the specified Lean version and download it when needed. The separate `elan` command provides manual control to install, select, run or uninstall Lean versions. The project supports version pinning, lockfiles, automatic switching, shell integration and CI/CD use. Installation options include shell instructions for Linux and macOS, a PowerShell method for Windows, and release downloads for supported platforms. The README recommends the Nixpkgs version on NixOS because toolchains downloaded by elan require patching there. Lake needs git to download dependencies. The project describes itself as a fork of rustup adapted for Lean infrastructure. elan is free at free, and the repository lists Apache-2.0 and MIT licenses. The releases page identifies v4.2.4 as the latest release.

plenv is a free Perl version manager for selecting the interpreter an application uses, helping keep development aligned with production. It installs Perl versions in the user’s home directory and switches between them in the shell. A `.perl-version` file can pin a Perl version to a directory, taking precedence over the global selection. Shell script wrappers called shims route Perl executable commands to the selected version. Setup instructions cover Bash and Zsh, with optional shell integration and autocompletion. Installation options include GitHub, an archive, and Homebrew on Mac OS X. The `perl-build` plugin supplies `plenv install`; `plenv-contrib` adds `use` and `lib` commands as a local::lib integration replacement. The README recommends Carton for upgrades and deployments. `migrate-modules` installs the newest module versions from one Perl environment into another, though the resulting versions may differ. The README lists Perl 5.8.1+ and Bash as dependencies, and curl for `plenv install-cpanm`. plenv supports Linux and macOS and is free software redistributable under the same terms as Perl itself.