I've been tinkering around with Rhombus and a bit of Shplait. Both feel great to use, but I did encounter a small hiccup: function currying. Shplait (and I think also Rhombus) treats (T, T) -> T, (T * T) -> T, T -> (T -> T) differently. This is reasonable, but writing the last variant (the curried variant), arguably the standard practice in FP, is quite tedious.
Unless I'm missing something, you need to hand-unroll the functions.

https://rhombus-lang.org/