Pickling something through an FSX session and unpickler in an app

[isaacabraham]

If I try to do the above, I get an error such as: -

Nessos.FsPickler.FsPicklerException was unhandled by user code
Message: An exception of type 'Nessos.FsPickler.FsPicklerException' occurred in FsPickler.dll but was not handled in user code
Additional information: Error deserializing object of type 'Microsoft.FSharp.Collections.FSharpList`1[MyNamespace.MyType]'.

Expected pickle of type 'Microsoft.FSharp.Collections.FSharpList`1[MyNamespace.MyType]' but was 'Microsoft.FSharp.Collections.FSharpList`1[FSI_0002.MyNamespace.MyType]'.

Should the FSI_0002 really be there? Is there any way to stop it happening?

[eiriktsarpalis]

Try resetting fsi. It looks like you are serializing an interaction type rather than a library type. On Thu, 27 Aug 2015 at 04:02 Isaac Abraham notifications@github.com wrote:

If I try to do the above, I get an error such as: -

Nessos.FsPickler.FsPicklerException was unhandled by user code Message: An exception of type 'Nessos.FsPickler.FsPicklerException' occurred in FsPickler.dll but was not handled in user code Additional information: Error deserializing object of type 'Microsoft.FSharp.Collections.FSharpList`1[MyNamespace.MyType]'.

Expected pickle of type 'Microsoft.FSharp.Collections.FSharpList1[MyNamespace.MyType]' but was 'Microsoft.FSharp.Collections.FSharpList1[FSI_0002.MyNamespace.MyType]'.

Should the FSI_0002 really be there? Is there any way to stop it happening?

— Reply to this email directly or view it on GitHub https://github.com/nessos/FsPickler/issues/62.

[isaacabraham]

Tried resetting. By "interaction type", I'm #loading the types in to FSI - is that the problem (rather than getting them by a #r)?

[krontogiannis]

Yes, you should #r the compiled assembly that you reference in your app. If you observe F# interactive, after running #load "foo.fs" you will see that it prepends FSI_XXXX in all namespaces declared in foo.fs.

[isaacabraham]

Mmmm, ok. This makes sense. It might be an idea to emit a warning if pickling a type that has FSI_ at the start - I didn't think it would matter.

[eiriktsarpalis]

@isaacabraham It's not inherently impossible to serialize FSI generated types, this is for example one of the things that Vagabond can do.

Should I close this?

[isaacabraham]

Up to you. Like I said, it wasn't obvious to me that using an interaction type wouldn't work in conjunction with a compiled type. Maybe just a warning would be sufficient here or something similar.

[eiriktsarpalis]

It does work. It's just that you need to have the same type definition loaded in the remote process as well, which is not trivial to achieve normally.

[isaacabraham]

Yeah. I was serializing data through FSI and deserializing in an application.

[adicirstei]

It would be nice though to be able to serialize/deserialize in interactive scripts.

[eiriktsarpalis]

@adicirstei you should consider using Vagabond. https://mbraceproject.github.io/Vagabond

[adicirstei]

@eiriktsarpalis I'll give it a try. Currently I am pretty happy with FsPickler. I'm using it to persist neural networks after the training is over. It's just for data.