dhall-lang
jsonnet
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dhall-lang | jsonnet | |
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113 | 48 | |
4,129 | 6,745 | |
0.5% | 0.9% | |
6.0 | 8.4 | |
about 2 months ago | 6 days ago | |
Dhall | Jsonnet | |
BSD 3-clause "New" or "Revised" License | Apache License 2.0 |
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dhall-lang
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Apple releases Pkl – onfiguration as code language
Fail to see how this is any different than Dhall (https://dhall-lang.org/) other than it produces plists too.
Well, Dhall provides something between JSON and a Turing complete language that can make a lot of configuration much quicker to write, if you can hack the functional syntax.
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Pkl, a Programming Language for Configuration
Kubernetes config is a decent example. I had ChatGPT generate a representative silly example -- the content doesn't matter so much as the structure:
https://gist.github.com/cstrahan/528b00cd5c3a22e3d8f057bb1a7...
Now consider 100s (if not 1000s) of such files.
I haven't given Pkl an in depth look yet, but I can say that the Industry Standard™ of "simple YAML" + string substitution (with delicate, error prone indentation -- since YAML is indentation sensitive) is easily beat by any of:
- https://nixos.org/manual/nix/stable/language/index.html
- (insert many more here, probably including Pkl)
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Why the fuck are we templating YAML? (2019)
Indeed why? However the conclusion I have is not to use JSON but to use a type safe configuration language that can express my intent much better making illegal states impossible. One example of such lang is Dhall.
Throwing in a plug for https://dhall-lang.org/
> Dhall is a programmable configuration language that you can think of as: JSON + functions + types + imports
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Is Htmx Just Another JavaScript Framework?
There are underpowered languages / tools, that can only solve a problem for which they are intended poorly. But not all limited tools are like that.
Say, eBPF is prominently not Turing-complete, which allows to guarantee that a eBPF program terminates, and even how soon. Still eBPF is hugely useful in its area.
Or, say, regular expressions are limited to regular languages; in particular, they famously [1] cannot process recursive structures, like trees. Still tools like grep / ag / rg are mightily useful.
Yes, I agree that YAML is underpowered for proper k8s configuration! But it's also too powerful for its own good in other aspects [2]. I wish Google used Dhall [3] or their own purely functional config language (FCL? I already forgot the name) instead of YAML; sadly, they did not.
[1]: https://stackoverflow.com/a/1732454/223424
[2]: https://ruudvanasseldonk.com/2023/01/11/the-yaml-document-fr...
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10 Ways for Kubernetes Declarative Configuration Management
Dhall: Dhall is a programmable configuration language that combines features like JSON, functions, types, and import capabilities. Its style leans towards functional programming, so if you're familiar with functional-style languages such as Haskell, you might find Dhall to be quite intuitive.
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Berry is a ultra-lightweight dynamically typed embedded scripting language
I've been thinking along these lines but more 'strongly validated' than statically typed in the sense that you'd be better off being able to load the entire config and then produce a list of problems (and should be able to offer good editor support if done correctly).
Though https://dhall-lang.org/ demonstrates that you can statically type quite a lot of configuration to great advantage, which appears to be programmatically embeddable in multiple languages per https://docs.dhall-lang.org/howtos/How-to-integrate-Dhall.ht...
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What Is Wrong with TOML?
I agree, I quite like https://dhall-lang.org/ for that reason. It strikes a good balance between features and being a config language.
jsonnet
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Pkl, a Programming Language for Configuration
Kubernetes config is a decent example. I had ChatGPT generate a representative silly example -- the content doesn't matter so much as the structure:
https://gist.github.com/cstrahan/528b00cd5c3a22e3d8f057bb1a7...
Now consider 100s (if not 1000s) of such files.
I haven't given Pkl an in depth look yet, but I can say that the Industry Standard™ of "simple YAML" + string substitution (with delicate, error prone indentation -- since YAML is indentation sensitive) is easily beat by any of:
- https://nixos.org/manual/nix/stable/language/index.html
- (insert many more here, probably including Pkl)
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Introduction to Jsonnet: The YAML/JSON templating language
jsonnet cli: link
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10 Ways for Kubernetes Declarative Configuration Management
Jsonnet: A data template language implemented in C++, suitable for application and tool developers, can generate configuration data and organize, simplify and manage large configurations without side effects.
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-❄️- 2023 Day 4 Solutions -❄️-
[Language: Jsonnet] (on GitHub)
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What Is Wrong with TOML?
Maybe you'd like jsonnet: https://jsonnet.org/
I find it particularly useful for configurations that often have repeated boilerplate, like ansible playbooks or deploying a bunch of "similar-but" services to kubernetes (with https://tanka.dev).
Dhall is also quite interesting, with some tradeoffs: https://dhall-lang.org/
A few years ago I did a small comparison by re-implementing one of my simpler ansible playbooks: https://github.com/retzkek/ansible-dhall-jsonnet
- Show HN: Keep – GitHub Actions for your monitoring tools
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That people produce HTML with string templates is telling us something
Apologies for the lack of context, and for missing this comment until today.
Both are tools for defining kubernetes manifests (which are YAML) in a reusable manner.
Jsonnet is a formally specified extension of JSON. It’s essentially a functional programming language (w/some object oriented features) that generates config files in JSON/YAML/etc, so it’s straightforward to determine whether an input file is valid, and to throw an error that points to an exact line if it’s not. It has a high learning curve, especially for people whose only experience is with imperative languages.
Helm charts also generate YAML/JSON config files, but they use Go templating. This is easier and faster to understand, since it’s mostly string substitution and not much logic (there’s conditionals, iterators, and very basic helper functions). Unfortunately a simple typo or mistake can cause errors that are difficult to diagnose (the message may indicate a problem far away in code from the actual mistake). It can also generate output that’s valid according to the string templating rules, but not what was intended, which can be very confusing to debug.
Despite these shortcomings, the vast majority of kubernetes applications are distributed as helm charts. I understand why things ended up this way, but I still wish it were more common for people to invest the upfront effort to learn the superior tool, so it could be more widespread.
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TOML: Tom's Obvious Minimal Language
I like Google's Jsonnet [1], which has all of this except for 4.
Jsonnet is quite mature, with fairly wide language adoption, and has the benefit of supporting expressions, including conditionals, arithmetic, as well as being able to define reusable blocks inside function definitions or external files.
It's not suitable as a serialization format, but great for config. It's popular in some circles, but I'm sad that it has not reached wider adoption.
- Jsonnet – The Data Templating Language
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Introducing JXC: An extensible, expressive data language. It's a drop-in replacement for JSON and supports type annotations, numeric suffixes, base64 strings, and more!
Something like jsonnet?
What are some alternatives?
kube-libsonnet - Bitnami's jsonnet library for building Kubernetes manifests
cue - CUE has moved to https://github.com/cue-lang/cue
cue - The home of the CUE language! Validate and define text-based and dynamic configuration
json5 - JSON5 — JSON for Humans
cdk8s - Define Kubernetes native apps and abstractions using object-oriented programming
Protobuf - Protocol Buffers - Google's data interchange format
Pulumi - Pulumi - Infrastructure as Code in any programming language. Build infrastructure intuitively on any cloud using familiar languages 🚀
terraform - Terraform enables you to safely and predictably create, change, and improve infrastructure. It is a source-available tool that codifies APIs into declarative configuration files that can be shared amongst team members, treated as code, edited, reviewed, and versioned.
toml.io - Source Code for toml.io
jsonlogic - Go Lang implementation of JsonLogic