This is a very common issue for learners (see [this SO question](https://stackoverflow.com/questions/65494134/how-do-you-call-an-uncurried-function-with-unit-in-rescript-reasonml/65548777#65548777)). We should give some pointers in the [uncurried function section](https://rescript-lang.org/docs/manual/latest/function#uncurried-function) on how to call an uncurried function with a single unit argument: E.g. this is a way to do it: ```rescript let echo = (. a) => a let _ = echo(. ignore()) ```