Puppy Linux vs Nix os

Puppy Linux requires 128MB of RAM and 333Mhz of CPU, although 256MB of RAM is recommended.

Since Puppy Linux is completely loaded and run off of RAM instead of HDD, it's read/write speed is not a factor.

A portable version, that can be carried on a thumb drive without requiring installation, weighs less than 100MB; a Live CD - less than 150MB. You can even save your settings and files for Puppy on the external device/media.

Running off a live CD also has security benefits, as your system will reset to the known config after each boot.

Puppy Linux offers a few different releases.

The first is an Ubuntu based release called Tahrpup, by using this version the user is able to take advantage of all software and support from Ubuntu.

The second version is called Slacko, which is built upon the Slackware binaries.

The third is called Wary and it is built to support older hardware than the rest.

And the fourth is called Quirky, which is used as a base to explore new ideas.

Puppy Linux offers an LTS release called Precise.

Sometimes, Puppy Linux is the only distro that works on an old machine: all other distros are more demanding.

JWM is a low resource window manager that is used in most Puppy Linux installs.

It has all of hackage in it's package manager (which is confusingly named "nix" as well) due to being based around hashing and allowing you to compile in a sort of virtual machine (really just changing the PATH variable temporarily) it solves many of the versioning problems that you commonly have with cabal. Here's a tutorial (there's many others as well) http://www.cse.chalmers.se/~bernardy/nix.html.
Also I should note that you can use the package manager a la carte on Mac and most any linux distro.

Since NixOS stores all its packages in isolation from each other in /nix/store and because of the declarative configuration model, upgrading NoxOS systems is extremely reliable. Furthermore, it gives you the ability to roll back upgrades.

Every package in your system is generated from a configuration file. This makes it very easy to reproduce that environment. Just copy the config file into a new machine and it's done.

You can use and test snapshots without rebooting. Booting into snapshots or test configurations is possible without risking the system's stability.

As everything is isolated, you can have on the same machine multiple configurations to meet project requirements that would be mutually exclusive on other OSes.