To be able to execute mymain, first it's necessary to compile nimhcr and nimrtl libraries from nim library. To do so, find nim installation directory (in my case it was installed with choosenim and installation directory was ~/.choosenim/toolchains/nim-0.20.2/ ), and execute "nim -d:release lib/nimrtl.nim" and "nim -d:release lib/nimhcr.nim". This will create the required libraries. Set LD_LIBRARY_PATH (or copy the libraries to a system library path) to where libnimrtl.so and libnimhcr.so are located.

Colon should be changed to equal:

var rect = Rect(....

This example is not working with "sdl2" wrapper, but can work if "sdl2_nim" wrapper is used:

nimble install sdl2_nim

Installation on Windows needs OpenCV (http://opencv.org) > 2.4.9 and freeglut (http://www.transmissionzero.co.uk/software/freeglut-devel/) (although in theory is only needed if you need OpenGL).

On installation guide, recommends downloading and installing from boost.org instead of distribution packages, as distribution packages change some things and make more difficult to follow documentation.