Error found:
in module Main
at tests/purs/failing/StandaloneKindSignatures4.purs:7:24 - 7:29 (line 7, column 24 - line 7, column 29)

  Could not match kind
          
    Symbol
          
  with kind
        
    Type
        

while checking that type "foo"
  has kind Type
while inferring the kind of To Int "foo"
in type class instance
               
  Main.To Int  
          "foo"
               

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