How to manage user-defined exception in library?

Learning
1

Hello, I’m trying to write an interpreter in ocaml and I’m using dune to build the project. And I run into a problem about managing user-defined exceptions.

I declare all my exceptions in lib/exception.ml, the file looks like this:

exception RuntimeError of string
exception InternalError of string
...

Then I wanna use these exceptions in another file lib/ast.ml:

open Exception

let eval = 
  ...
  raise (RuntimeError "error")
  ...

However, dune build gives me this error:

File "lib/ast.ml", line 1:          
Error: The implementation lib/ast.pp.ml
       does not match the interface lib/.tinyML.objs/byte/tinyML__Ast.cmi: 
       The exception `RuntimeError' is required but not provided

I can solve this error by rebind the exception: lib/ast.ml

open Exception
exception RuntimeError = Exception.RuntimeError

let eval = 
  ...
  raise (RuntimeError "error")
  ...

I wonder why I need to rebind exception to work, and whether there is a better way to manage exceptions.

Thanks! :smiley:

2

I find the problems, that’s because I define exception in ast.mli :sweat_smile:

exception RuntimeError of string

Never mind.