Can we make unwrap_{left,right} not require the generic parameter with the unused type?

[schoen]

Project

compiler

Describe the feature

Right now the macros unwrap_left and unwrap_right require you to specify the type of the Either branch that you're not using. For example, if you unwrap_right an unconfidential Amount1's Some object, you have to specify the type of the confidential amount that you don't expect as output, like

let amt: u64 = unwrap_right::<(u1, u256)>(amt1);

Could we make unwrap_left and unwrap_right figure out these types automatically rather than specifying them? E.g. just left amt: u64 = unwrap_right(amt1) without needing to say what the Left object would have been if it had been present, since we're also asserting that it's not present?

[apoelstra]

It's technically possible but it'd require a real type inference engine. This would be a big jeb. Right now we just have a series of special-cases where we can "infer" types that are obvious from locally-available information.

I had been hoping that we could start using https://github.com/canndrew/simplicity-ng/tree/master/core-tt (with some sort of restricted API to avoid using dependent types, which have some exponential blowups in them) but I don't think it's ready to go.