In theory that's true for many of the kinds of Turing-incomplete languages we care about. (Eg it's not true for JPG or for (proper) regular expressions.)
From Dhall's docs (emphasis mine):
> Note that a “finite amount of time” can still be very long. For example, there are some short pathological programs that take longer than the heat death of the universe to evaluate. The main benefit of evaluation being finite is not to eliminate long-running programs but to make them significantly less probable. In practice, you will discover that you will rarely author a configuration file that takes a long time to evaluate by accident.
> For example, Dhall does not provide language support for recursion. If you try to define a recursive expression or function you will get a type error. Lists are the only recursive data structure and the only way to build or consume lists is through safe primitives guaranteed to terminate, like List/fold. This restrictive programming style keeps code simple and makes expensive code more obvious (both to the code author and reviewer).
I guess I don’t care much if a configuration language takes a long time in some pathological case (a user writes a loop that doesn’t terminate). Such cases are already too rare to justify a dedicated language. And if the concern is bad actors, then a bad actor wouldn’t have to try to hard to get a Dhall program to run for a long time (copy paste something from the Internet). The more compelling reason to use Dhall is the static type system which is sadly uncommon among configuration languages.
So common that it justifies a change of language? "Oops, this thing that should have run for 5s has run for 30s, something must be wrong, <cancel>". You can even automate that reasoning by way of a timeout. In a hypothetical world where I'm choosing between two otherwise exactly equal configuration languages, I suppose this would give the advantage to Dhall, but honestly I'd probably pick TypeScript because making an entire org learn a new syntax is far more trouble than that saved by non-Turing-completeness.
From Dhall's docs (emphasis mine):
> Note that a “finite amount of time” can still be very long. For example, there are some short pathological programs that take longer than the heat death of the universe to evaluate. The main benefit of evaluation being finite is not to eliminate long-running programs but to make them significantly less probable. In practice, you will discover that you will rarely author a configuration file that takes a long time to evaluate by accident.
> For example, Dhall does not provide language support for recursion. If you try to define a recursive expression or function you will get a type error. Lists are the only recursive data structure and the only way to build or consume lists is through safe primitives guaranteed to terminate, like List/fold. This restrictive programming style keeps code simple and makes expensive code more obvious (both to the code author and reviewer).