It hasd a limpid comment at the top that contains its real danger; I keep trying to get a much stronger warning added, but despite repeated requests that one is still there and still does not have a proper warning.

It is an example of how to override every setting. It does so by overriding every setting, with the defaults for one particular version of xmonad; this means you do not inherit any defaults, and if the defaults change in a later version then you will not see those changes (this bit a lot of people when dmenu changed its usage and we updated the mod-p binding, but people using that "example" didn't get the change because the old way was hardcoded in their configs. That was what convinced me that that example was Evil). If we were to change the implementation in certain ways, or if you use an example from a later version with an earlier version (someone popped up on IRC with that problem the other day), it wouldn't even compile.

The correct place to start is shown on the xmonad wiki:

(which is actually valid for 0.10 and later).

If you want to truly start "from scratch", https://wiki.haskell.org/Xmonad/Config_archive/John_Goerzen%27s_Configuration is a little dated but still valid.

(I'm still working my way through trying to get the wiki up to date. Nobody else seems interested in doing so, sigh.)
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