Dhall-haskell: Should dhall-json always pretty-print JSON?

[Gabriel439]

I was having difficulty thinking of a use case where a user wouldn't want to pretty-print the JSON output. I was wondering if we should pretty-print the output by default

[ocharles]

Note that if you want to argue for the Unix way there is always the pipe | jq . to pretty print the output.

On Tue, 27 Nov 2018, 9:56 pm Gabriel Gonzalez <[email protected]
wrote:

I was having difficulty thinking of a use case where a user wouldn't want
to pretty-print the JSON output. I was wondering if we should pretty-print
the output by default

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[Gabriel439]

I view pretty-printing as ancillary to jq's purpose. If anything, I think jq is an example of why we should do this since jq does not delegate responsibility for pretty printing to another tool

[ocharles]

I don't understand. Jq doesn't care if your input is or isn't pretty printed. However, it is a tool that solves the general problem of "I want this JSON pretty printed". The purpose of dhall-to-json is just to convert Dhall to JSON. Personally I have no feeling either way on the matter though, technically either is an arbitrary choice

[joneshf]

Is the proposal to flip the boolean, or is the proposal to remove it and always pretty print?

[Gabriel439]

@joneshf: Remove it and always pretty print

Note that if I were to o this I'd probably roll this out in two phases:

• Phase 1 - always pretty print and ignore the option
• Phase 2 - remove the option

[justinwoo]

Sorry to comment late if the decision has already been made, the one thing I care about is if the output has newlines or not. Having this be a flag would be useful for me, but otherwise I will use other tools to substitute newlines.

[Gabriel439]

@justinwoo: The decision hasn't been made, yet! 🙂

I can definitely preserve a newline-free option if you need one

[Profpatsch]

@justinwoo Let me guess, so that it’s easier to use with ad-hoc perl scripts? ;)

[justinwoo]

it's useful for when you work with newline-delimited JSON and other things in general, but yes, this would also help me use jq and perl

[Gabriel439]

So then the transition can be done in the following phases:

• Add a --compact flag that enforces the current default of single-line output
• Change the default to --pretty
• Remove the --pretty flag

[Gabriel439]

I'm adding a Hacktoberfest label to this to complete the next step of the transition to make --pretty the default behavior for dhall-to-json

[DKurilo]

Wanted to do something simple and found that:

1. I can't build it with nix on my laptop (MacOS), because this line:
   https://github.com/dhall-lang/dhall-haskell/blob/master/default.nix#L20
   make nix trying to build website with linux version of ghcjs.
2. As it's in README, I need to build modules with cabal while under nix-shell. As I see, I need v2 cabal command. Like cabal v2-run dhall-json -- --file ./examples/travis.yml to work with project.
   I can fix it, but I've never worked with this project before, so my question: Are these things really issues or did I understand it wrongly?

[sjakobi]

2. As it's in README, I need to build modules with cabal while under nix-shell. As I see, I need v2 cabal command. Like cabal v2-run dhall-json -- --file ./examples/travis.yml to work with project.

You can alternatively use stack if you are more comfortable with that:

$ stack build dhall-json
$ stack exec -- dhall-to-json --file ./examples/travis.yml

I mostly use cabal, without the nix-shell.

[DKurilo]

I created pull request. Surely, it's very simple changes. Everything is already done. And I can create one more PR to remove --pretty right now.
But I think it's really breaking changes, because anyone who , like @justinwoo , as I understand, relies on new lines between multiple generated jsons will update dhall-to-json they will have unpredictable errors (maybe even in prod).