this suffers from the same thing that all "terse" languages like this does; it becomes an impenetrable obfuscated mess to untangle for anything that is not trivial.
RegEx, List Comprehensions, etc all suffer from the same thing. A human can only hold so much "state" in their brain. Making languages that are this terse impossible to read and reason about without an extreme amount of effort.
Your last example is proof of this and you imply the same thing saying you had to solve it with pencil and paper to verify it works.