An immutable loop structure `loop let`

[OJarrisonn]

First of all guys thanks for the feedback, as I said this is just a scratch of the idea in my mind, but trust me, it can go beyond the current ways to achieve similar behaviour

@theme

Here's an implementation of your loop construct without needing new syntax. I think that this structure is too niche to need new syntax.

Your repeat function is just a partial implementation of loop let since repeat doesn't support fallible patterns, while loop let does support.

@SkiFire13

The real benefit of tail calls is when you have different functions calling each other in a tail-recursive way. You cannot do that with a loop like this.

If fact, loop let would need some special treatment to support this crossed recursion

@scottmcm

If we had become for guaranteed tail call elimination, would you still want to write these things like this instead of recursively?

We still don't have become and i dont think we'll ever see it. Also become is a terrible choice of name, recur would be a better option.

Again thanks for the feedback it helps me strengthen the proposal