You're linking to an old version. Here is the current version: http://hackage.haskell.org/package/turtle/docs/Turtle-Tutori...

Yes, I skimmed it. But please note that I wrote about "simply" calling external executables, where you can just type the name of a program and have it run. Turtle doesn't even try to allow this (while PowerShell has it), instead going in the opposite direction:

> Most of the commands in this library do not actually invoke an external shell or program. Instead, they indirectly wrap other Haskell libraries that bind to C code.

inshell "ls" would do what you are talking about, unless your bar for simple is just typing ls.