> How about cabal-install using the YAML format as hpack has proven that it > works very well for expressing the existing .cabal files? YAML is simple, > flexible and open, used across many tools so the knowledge of format is > more widely sharable which has its advantages. Are there reasons to keep > using the cabal format other than the legacy reasons and the pain of asking > everyone to move to another format?
I understand YAML is a very popular format, but it is not all roses. It's an extremely complicated format (http://yaml.org/spec/1.2/spec.html). Cabal's lexical format is very simple, because it doesn't really need to support much (the rest is deferred to sub-parsers on fields.) In some since, YAML is overkill for Stack, which actually doesn't use very many of its features (https://docs.haskellstack.org/en/stable/yaml_configuration/) If I were designing a package ecosystem from scratch, I'm not sure what format I would pick. Take Rust Cargo; they didn't use YAML, they used TOML (https://github.com/toml-lang/toml) in no small part due to the fact that YAML is complicated. I'd want the output to be associated with locations so I could give error messages that refer to the input file; no one does that today... > Inputs from original stack authors might also be useful on why they chose > YAML over .cabal. I guess it might be similar to the reasons why someone > wrote hpack to generate .cabal from YAML. Also they were starting fresh and > so did not have to manage a disruptive change. But I fear if they will be > willing to go for a closed format against an open format now even if some > of the problems of the format are addressed. Maintaining a closed format > perennially is also an issue unless it is very well thought out and does > not require any changes. I suspect the reason is much more banal: Cabal's parser implementation is pretty byzantine and difficult to use. So rather than fight something like that, just use something will a nicer API. Edward _______________________________________________ Haskell-community mailing list Haskell-community@haskell.org http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-community
