Use unicode characters for Xmonad workspaces

I want to use Unicode characters from the Nerd Fonts for my workspaces in Xmonad.

myWorkspaces = ["1:", "2:", "3:", "4:", "5:", "6:ﱘ", "7:", "8:", "9:"]

For reference:

However, I get the following error on compilation:

xmonad.hs:191:13: error:
    lexical error in string/character literal at character '\62057'
    |
191 |         ["1:", "2:", "3:", "4:", "5:", "6:ﱘ", "7:", "8:", "9:"]
    |             ^

Please check the file for errors.

Warning: Missing charsets in String to FontSet conversion 

Is there any chance to use a full set of nerd fonts unicode characters? I have seen that others use a subset of unicode in their config.