Edit: Please disregard, wrong person
> terraform modules are functions
You seem to have found this feature useful. Doesn't that answer your question about why you would want a configuration language to have functions?
> terraform modules are functions
You seem to have found this feature useful. Doesn't that answer your question about why you would want a configuration language to have functions?
... all requiring potentially complex generation of configuration.
In that sentence, I believe their meaning is that Terraform's language is already capable of generating configuration, and in fact this is a feature which is quite essential to Terraform's use. They acknowledge that all these projects (Nix, Terraform, Bazel, etc) already utilize relatively sophisticated programming languages for configuration. Nickel merely aims to be a better designed language for the purpose.