[CodeAndCuffs]

Fp-ts adds some amazing functional tools. Io-ts, which is built off of it, adds great run time type validation.

I can define types using io-ts, infer a true typescript type from that to put in my d.ts files to get full ts type checking, and also have run time type checks, all from the same single definition.

The initial learning curve is admittedly a little steep, but once you have it down it's a breeze to use, and delightful.