Hello 
. I’ve used the famous dts2hx (ahem @haxiomic ) to generate externs from the Node library simple git. But I ran into a world of trouble trying to call functions there.
For starters, I’m trying to get the status of a git repo using simpleGit.status(). And I actually managed to do it IF I make a SMALL change in the transpiled JS. And this tells me I’m very close to the result, but oh, yet so far 
It all seems to revolve around an interface that defines a callback function via a generic type. This is the interface in TS:
/**
* The node-style callback to a task accepts either two arguments with the first as a null
* and the second as the data, or just one argument which is an error.
*/
export interface SimpleGitTaskCallback<T = string> {
(err: null, data: T): void;
(err: Error): void;
}
And this is the same in Haxe:
typedef SimpleGitTaskCallback<T> = {
@:overload(function(err:js.lib.Error):Void {})
@:selfCall
function call(err:Dynamic, data:T):Void;
};
Now, I’m not ExEx (extern expert) but it’s strange that there’s that selfcall there. From @haxiomic’s earlier help I remember that the selfcall is used to call a class. But this is a typedef. And it’s not even a typedef for a class, but for a function. I’m probably missing something here, but anyway, I did what I could with that Haxe code. Which is this:
I defined a function like this:
public static function statusResultCallback(err:Dynamic, data:StatusResult):Void {
console.dir(err);
console.dir(data);
}
And then I assigned it like this:
var funcStatusResultCallback:SimpleGitTaskCallback<StatusResult> = {call: statusResultCallback};
But… when calling
simpleGit.status(null, funcStatusResultCallback);
I get nothing.
The involved lines of the transpiled code are this:
Test.statusResultCallback = function(err,data) {
console.dir(err);
console.dir(data);
var funcStatusResultCallback = { call : Test.statusResultCallback};
simpleGit.status(null,funcStatusResultCallback);
};
And this doesn’t work.
BUT
If I directly call Test.statusResultCallback, it works!
simpleGit.status(null,Test.statusResultCallback);
So… I suspect I’m missing something around how I could make that typedef into a function argument. I tried all manners of things, such as changing the return type of the function, or what is contained in the declaration of the function object, but I get compile errors this way and that. For the sake of your sanity, I’ll not go into details about all the weird hacks I’ve been doing 
To ease the effort of the kind soul that can take a look at this, I pushed this to GitHub. Just npm install it, run npx dts2hx simple-git and you’re good to go. You don’t need to create a Git repo to test the code 
it will use its own repo (oh, the amusement of giving a Git repo to help solve a Git library problem using its own Git repo ; should’ve posted this on GitHub, would’ve been even better)
And guess what, I’ll probably turn this into a “tutorial-repo”, a-la my live reload boilerplate repository. I’ve been struggling with quite a few externs situations and probably some knowledge sharing with the community wouldn’t hurt.