Constant Relative Imports

[rohan-datar]

This probably is a relatively niche issue, so I understand if what I'm trying to do here isn't possible in pkl, but I thought I'd ask the question anyway.

I'm trying to build a relatively complex template, and as a result some template files rely on information contained in other ones. Here's a minimal example:

In package template

// template/foo.pkl

name: String
value: Int
config: Listing<String>

and another template that depends on foo.pkl

// template/bar.pkl

foo: Module
config: Listing

output {
   rendererer = new JsonRenderer {
       converters {
         [Listing] = // function that depends on foo.config
       }
    }
}

Then I have a package Configurator that depends on template.

Configurator
├── configuration1
│   ├── foo.pkl
│   ├── bar.pkl
├── configuration2
│   ├── foo.pkl
│   ├── bar.pkl
...

where the templates are filled out like this:

// configuration1/bar.pkl

amends "@template/bar.pkl"

foo = import('./foo.pkl')
config {
   // some values here
}

This works fine, but I am in a situation where the could be hundreds of different configurations and putting foo = import("./foo.pkl") inside every single bar.pkl is very inconvenient.

Is there a way I can create a relative import (or something else that allows me to access the contents of foo.pkl) in the parent template? I can enforce the relative path of the configuration files within each instance of the template, but it is easy for a user to forget the import expression, which breaks the template in unexpected ways because foo is then instantiated as an empty module.

Is there a better solution for this?

[bioball]

I think you are looking for sibling imports?

See this post here: #902 (reply in thread)

[rohan-datar]

That might work. I'll have to try it

[rohan-datar]

So I tested this out and I just get an error.

I updated my template to look like this:

// template/bar.pkl

import "bar.pkl"
import* "**/foo.pkl" as fooModules
import "foo.pkl" as Foo

local path = bar.relativePathTo(module).join("/")

hidden fixed foo: Foo = fooModules["\(path)/foo.pkl"]
config: Listing

output {
   renderer = new JsonRenderer {
       converters {
         [Listing] = (x) -> "\(foo.value)-\(x)"
       }
    }
}

and I have config/foo.pkl and config/bar.pkl

// config/foo.pkl
amends ".../template/foo.pkl"

name = "foo"
value = 42
config {
    "foo"
    "bar"
    "baz"
}

// config/bar.pkl
amends ".../template/bar.pkl"

config {
    "conf1"
    "conf2"
}

Running pkl eval config/bar.pkl produces the following error

–– Pkl Error ––
No descendent path exists between modules `file:///home/rdatar/pkl-test/template/bar.pkl` and `file:///home/rdatar/pkl-test/config/bar.pkl`.

7 | local path = bar.relativePathTo(module).join("/")
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^
at bar#path (file:///home/rdatar/pkl-test/template/bar.pkl, line 7)

9 | hidden fixed foo: Foo = fooModules["\(path)/foo.pkl"]
                                          ^^^^
at bar#foo (file:///home/rdatar/pkl-test/template/bar.pkl, line 9)

15 | [Listing] = (x) -> "\(foo.value)-\(x)"
                           ^^^
at bar#output.renderer.converters[#1].<function#1> (file:///home/rdatar/pkl-test/template/bar.pkl, line 15)

106 | text = renderer.renderDocument(value)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
at pkl.base#Module.output.text (https://github.com/apple/pkl/blob/0.27.2/stdlib/base.pkl#L106)

The problem seems to be with path, using a self import and relativePathToModule(module) tries to find the relative path from template/bar.pkl to config/bar.pkl whereas what I want to get is effectively the parent directory of config/bar.pkl. What would you suggest as a solution to that?
My initial idea was to try to use reflect.Module(module).uri and try to strip the filename from the URI somehow to retrieve the URI of the parent directory, but I wanted to get your thoughts as well

[rohan-datar]

I tried this:

// template/bar.pkl

import "pkl:reflect"
import* "**/foo.pkl" as fooModules
import "foo.pkl" as Foo

local path = reflect.Module(module).uri.dropLastWhile((char) -> char != "/")

hidden fixed foo: Foo = fooModules["\(path)foo.pkl"]
...

But now get a different error

–– Pkl Error ––
Cannot find key `"file:///home/rdatar/pkl-test/config/foo.pkl"`.

11 | hidden fixed foo: Foo = trace(fooModules)["\(path)foo.pkl"]
                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
at bar#foo (file:///home/rdatar/pkl-test/template/bar.pkl, line 11)

17 | [Listing] = (x) -> "\(foo.value)-\(x)"
                           ^^^
at bar#output.renderer.converters[#1].<function#1> (file:///home/rdatar/pkl-test/template/bar.pkl, line 17)

106 | text = renderer.renderDocument(value)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
at pkl.base#Module.output.text (https://github.com/apple/pkl/blob/0.27.2/stdlib/base.pkl#L106)

It appears that fooModules is empty and the glob import doesn't work?