WIP: Add file writing and reading

[MMagueta]

No description provided.

[MMagueta]

So @dbrattli here I did something ugly. I tried to get the OpenTextMode union working with its different open modes but I could only get it working by adding the read, write and update to the same union context. What would you recommend to do here?

[dbrattli]

@MMagueta Yes this looks like the right thing to do 👍

[MMagueta]

I still need to fix this test, don't take it for granted

[dbrattli]

The other way would be to fix the union to be:

[<Erase>]
type OpenTextMode =
    | OpenTextModeUpdating of OpenTextModeUpdating
    | OpenTextModeWriting of OpenTextModeWriting
    | OpenTextModeReading of OpenTextModeReading

then you can do:

    let result = builtins.``open``(StringPath "test.txt", OpenTextModeWriting OpenTextModeWriting.Write)

But it feels a bit verbose, so I think it's OK to collapse them as you suggest. The inspiration for the code is btw:

• https://github.com/python/typeshed/blob/master/stdlib/_typeshed/__init__.pyi#L156
• https://github.com/python/typeshed/blob/master/stdlib/io.pyi#L165

[MMagueta]

[<Erase>]
type OpenTextMode =
    | OpenTextModeUpdating of OpenTextModeUpdating
    | OpenTextModeWriting of OpenTextModeWriting
    | OpenTextModeReading of OpenTextModeReading

It might be an error I induced, but that was the first thing I tried and the compilation wasn't quite right. Are we supporting nested union structures? I noticed that a lot of the class features in F# aren't being translated, so I thought it might be a wip.

[dbrattli]

Closing because of #58