I wrote:
> 
> Can anyone see this error?
[]
> This expression has type int but is here used with type unit
[]
>   method run_file filename : int =
[]
>         Py_exec_module.exec_file (self:>interpreter_t)
                                    ^^^^^^^^^^^^^^^^^^^

I have found the error. While I updated the interface for the module
correctly, (that is, the class type) I did not update the 
abstract interface containing the more abstract class type
to which the 'self' is coerced in the indicated term: in the class type
'interpreter_t',
method 'run_file' has return type 'unit'. Because the inference engine
has not
yet deduced the type of 'run_file' for class type 'py_interpreter', it
uses
the information from the coercion to assume it returns 'unit', then
reports
an error when later finding it actually returns an 'int'.

-- 
John Skaller, mailto:skaller@maxtal.com.au
10/1 Toxteth Rd Glebe NSW 2037 Australia
homepage: http://www.maxtal.com.au/~skaller
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