The point is you could all get that with YAML without plonking dhall on top if you had a properly designed schema.

Hence it's a hack to circumvent badly designed / no schema.

Lets look at a specific example. Take Kubernetes: everything is yaml, with complete schemas, all the way down. From your perspective this is configuration utopia, right? Meanwhile back in reality k8s is the poster child of "yaml hell". From the day it was released, people took one look at it, gave it a giant NOPE and instantly spawned half a dozen templating languages. The most popular of these is helm, which has a terrible, no good, very bad design: full of potential injection attacks from purely textual string substitution, manually specified indentation to embed parameterized blocks, virtually no intermediate validation, no way to validate unused features, etc etc

Compare to dhall which publishes a complete set of dhall-k8s schema mappings which enables you to factor out any design you want down to as few configuration variables as you like, while validating the configuration generators themselves at design time. https://github.com/dhall-lang/dhall-kubernetes#more-modular-...

>Lets look at a specific example. Take Kubernetes: everything is yaml, with complete schemas, all the way down. From your perspective this is configuration utopia, right?

LOL! No, their schemas are horribly designed and half of their YAML should really be APIs.

But it's hella popular.

>Compare to dhall

Which isn't.

Your argument is akin to "why do you need a high-level language? just write it in assembly, C is just a hack to circumvent badly designed assembly". If a 'properly designed yaml schema' was sufficiently powerful for all these use-cases then why does everyone and their third cousin come up with new configuration languages every week? Clearly they do, thus I must reject the null hypothesis and conclude that plain yaml schemas are not sufficient.

These arguments aren't holding any water.

>If a 'properly designed yaml schema' was sufficiently powerful for all these use-cases then why does everyone and their third cousin come up with new configuration languages every week?

Coz they fucked up/didn't fix their schema designs and people keep trying to work around that?

I thought I was being very explicitly obvious about this.

Programming is a history of bad designs being worked around with awkward hacks. This is nothing new.

Ah so your argument is that they just aren't doing it right, that a true yaml schema designer wouldn't make this mistake. It's just a mistake.. which keeps being made over and over by everyone that does configuration. Sounds like a no-true-scotsman and "it's the children who are wrong" to me. Can you give any examples of a popular correctly designed yaml schema?

I'm saying that a schema designers reaction to their users using jinja2 or dhall on their YAML ought to be to fix their schema so it's not necessary.

There are plenty of properly designed YAML schemas where people never feel the need to use something like dhall or jinja2.