Use less permissive types in the config monoids

[sjakobi]

ConfigMonoid (and probably other config monoids too) contains a few fields that have more permissive types than necessary. This has the effect that bad inputs go undetected or result in errors that are reported out of context or only after the inputs have been passed to ghc.

A few of the problematic fields:

• configMonoidWorkDir
• configMonoidOs
• configMonoidExtraIncludeDirs

Example interaction:

$ stack --extra-lib-dirs --oops build
these-0.7: unregistering (local file changes: Control/Monad/Chronicle.hs Control/Monad/Chronicle/Class.hs Control/Monad/Trans/Chronicle.hs Data...)
these-0.7: configure
Configuring these-0.7...
Warning: 'extra-lib-dirs: --oops' directory does not exist.
...

Compare this to the error message for an argument that must be a Path Abs Dir:

$ stack --stack-root --oops path
option --stack-root: Failed to parse absolute path to directory: '--oops'

Usage: stack [--help] [--version] [--numeric-version] [--hpack-numeric-version]
...

[chrisdone]

Agreed, do you want to submit a PR for this?

[sjakobi]

Agreed, do you want to submit a PR for this?

Yes I've already started to work on this.

One thing that would be useful for this, are FromJSON instances for the four Path types. I assume you wouldn't want these in path itself.
Should I make a path-aeson-instances or even a path-instances package?

[chrisdone]

I suppose I wouldn't mind including instances for FromJSON in path itself. It should have four instances, one for each possible path combination. I'll merge a PR to path which includes FromJSON and ToJSON instances.

[sjakobi]

I suppose I wouldn't mind including instances for FromJSON in path itself.

Great! I'll make a PR.

[chrisdone]

Here are some necessary ingredients to achieve what you'd like for e.g. extra-lib-dirs:

• The option parser for extra lib dirs
• How to define an optparse-applicative parser for a custom type
• You already know where the config types are. 👍

It may eventually be a nice idea to include such an optparse combinator in the path package itself eventually, but for now it can be put in Options.hs.

Do you have everything you need? ☝️ 😄

[sjakobi]

Do you have everything you need?

Thanks! :)

I'll ask if need anything else!

[sjakobi]

I'd like to use better types in Urls and UrlsMonoid but I'm not sure what to pick:

• URI from network-uri?
• URL from url (not updated since 2012)?
• Something else?

[chrisdone]

Possibly uri-bytestring?