AuthMethods + Template Haskell experiment #1918
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Signed-off-by: Mihovil Ilakovac <[email protected]>
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Interesting experiment @infomiho , and good job on learning more about TH in practice!
Looking at the PR, it seems to me like the conclusion is that TH brought more complexity then it took away. How are you thinking about it?
AUthMethods part of PR looks reasonable to me, although I would have to see it without TH to make proper review. But TH changes I think you can drop. It would be interesting to understand better what you tried to solve with them, and see if we can achieve that in some other way -> maybe by organizing some code differently, or by using typeclasses, or something like that. Maybe even some TH again, but I think it will be much simpler, if it makes sense at all.
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| userSignupFieldsForExternalAuth :: ExternalAuthConfig -> Maybe ExtImport | ||
| userSignupFieldsForExternalAuth = userSignupFields | ||
| generateIsAuthMethodEnabled :: Q [Dec] |
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Since TH can be hard to undrsatnd, and here it certainly is a bit ahrd to read, it would be good if you could document here, in a comment above it, what does this TH generate.
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| import Data.Data (Data) | ||
| import Language.Haskell.TH |
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Unqalified, unlisted import -> not a good practice!
I would suggest importing it qualified as TH.
| userSignupFieldsForEmailAuth :: EmailAuthConfig -> Maybe ExtImport | ||
| userSignupFieldsForEmailAuth = userSignupFields | ||
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| userSignupFieldsForUsernameAuth :: UsernameAndPasswordConfig -> Maybe ExtImport | ||
| userSignupFieldsForUsernameAuth = userSignupFields | ||
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| userSignupFieldsForExternalAuth :: ExternalAuthConfig -> Maybe ExtImport | ||
| userSignupFieldsForExternalAuth = userSignupFields |
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What you can do, if you want is, use typeclass for something like this, which has a method userSignupFields, and each of these types will implement it. That might be a bit more elegant, depending on how you use it though, what you really need.
| configType GitHub = ''ExternalAuthConfig | ||
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| -- Generate the AuthMethods data type | ||
| -- data AuthMethods = AuthMethods |
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Seems to me like you ended up defining this relationship anyway above! Becauwe you defined it via configType at the end, only to then generate AuthMethods from that. So did you really gain anything?
I was thinking how can we make adding a new auth method a more type safe process. Since we are kinda loosely defining them by adding a new key in the
AuthMethodsrecord, we don't really have a union data type over which we can force exhaustive pattern matches.I've played a bit with Template Haskell to try to change that.