Create TS definition type

[Taranys]

Prerequisites

• I have read the Contributing guidelines
• I have read the Code of conduct and I agree with it

Description

Add TS definition file to have type checking

Expected behavior

Using immutadot properly with typescript

[hgwood]

Not very useful without this: microsoft/TypeScript#12290

[KiaraGrouwstra]

To comment on that, from what I can see this library appears to parse paths from strings such as 'nested.prop'. TypeScript currently lacks ways to operate on string literals, and afaik thus far this is so far deemed out of scope (microsoft/TypeScript#15645 (comment)).

I wouldn't mind seeing that reconsidered, as I feel this is a valid use-case for not only this library but also the likes of Lodash. Until that happens though, I fear the best thing TS might be able to handle is paths where the constituents are not mashed into one string.

[katywings]

Little idea for this: Now with ts in babel it would be possible to create a babel macro that just converts a object path to a string, basically:
turnTostringMacro(myObj.andSoOn) // transpiles througj babel-macro to "myObj.andSoOn". Just as an idea :)

Then for ts you would only need a function declaration which takes "any" and returns "string" ;)