Answer: How to make an tail recursive function and test it in ReasonML?

	let sum = n => {
	let rec loop = (n, k) =>
	if (n == 0) {
	k(0);
	} else {
	([@tailcall] loop)(n - 1, x => k(x + n));
	};
	([@tailcall] loop)(n, x => x);
	};

view raw tailcall.re hosted with ❤ by GitHub

	let sum = n => {
	let rec loop = (n, k) =>
	if (n == 0) {
	k(0);
	} else {
	loop(n - 1, x => k(x + n));
	};
	loop(n, x => x);
	};

view raw unannotted.re hosted with ❤ by GitHub

How do you test if this reasonml function is tail recursive. The simple version show you the unannottated function and usingTailCall.re show its annotated in reasonml.

Call in terminal with:

ocamlc -annot -o tailCall -pp "refmt -p ml" -impl tailCall.re

You can check where the tail calls are with:

grep call -A1 tailCall.annot 

Source: https://stackoverflow.com/a/40401233/2336356
Sketch: https://sketch.sh/s/eBl2Z0Wvd21azKu6SFzb9j/