failed: exec: "pkl": executable file not found, in go bindings project, why?

[kaihendry]

I noticed in my Go pkl binding project that it appears to not work without the pkl binary... Am I going crazy?

Using docker image sha256:b0fea0113abfa8438900974640aca1b6e7aeff6539a015b6fb3e04c9be07a822 for golang:latest with digest golang@sha256:2b1cbf278ce05a2a310a3d695ebb176420117a8cfcfcc4e5e68a1bef5f6354da ...
$ go test
go: downloading github.com/apple/pkl-go v0.9.0
go: downloading github.com/vmihailenco/msgpack/v5 v5.4.1
go: downloading github.com/vmihailenco/tagparser/v2 v2.0.0
--- FAIL: TestRedisBinds (0.00s)
    main_test.go:63: genRedisBinds(spec/1.pkl) failed: exec: "pkl": executable file not found in $PATH

My .gitlab-ci.yml looks like:

test:
  image: golang:latest
  script:
    - go test

[kaihendry]

Reproduced the problem here: /~https://github.com/kaihendry/pkl-redis/actions/runs/13389969491/job/37395258183

[StefMa]

The go binding doesn't work without the pkl binary. This was mentioned there #849 (reply in thread) and somehow also documented in the quickstart guide.

[kaihendry]

Oh! I would like to please understand how the generated code even invokes the pkl /~https://github.com/kaihendry/pkl-redis/tree/main/gen/control

Or is it via the module? 🕵️

[bioball]

Pkl is a language that requires the interpreter to produce data. It's not like JSON, YAML, etc, which are static formats that just need to be parsed.
Codegen just gives you type-safe access to the Pkl data once it has been evaluated.

The normal path for using pkl-go is to include the Pkl CLI, and at runtime, the Go program will spawn the CLI as a child process for evaluation. That is what happens when you use the evaluator API in Go.

There is another alternative, which is to pre-bake the Pkl into data, and simply unmarshall that on the Go side.

Sidenote 1: I should update /~https://github.com/apple/pkl-go-examples with an example of this technique
Sidenote 2: In the future, we plan on providing a C library for pkl as an alternative way to bind to the evaluator.