Error found:
in module Main
at tests/purs/failing/ProgrammableTypeErrors.purs:17:13 - 17:27 (line 17, column 13 - line 17, column 27)

  A custom type error occurred while solving type class constraints:

    Cannot show functions


while solving type class constraint
                          
  Main.MyShow (Int -> Int)
                          
while applying a function myShow
  of type MyShow t0 => t0 -> String
  to argument \$0 ->      
                (add $0) 1
while checking that expression myShow (\$0 ->      
                                         (add $0) 1
                                      )            
  has type String
in value declaration main

where t0 is an unknown type

See https://github.com/purescript/documentation/blob/master/errors/NoInstanceFound.md for more information,
or to contribute content related to this error.