MacPorts

Package management system for Mac OS X, formerly known as DarwinPorts.

https://www.macports.org

The authors explain why they use Tcl, here:

• https://web.archive.org/web/20051126152950/http://opendarwin.org/pipermail/darwinports/2002-October/015387.html
• https://web.archive.org/web/20070102210413/http://opendarwin.org/pipermail/darwinports/2005-January/023888.html
• https://web.archive.org/web/20180417171540/http://permalink.gmane.org/gmane.os.apple.macports.devel/22937