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Yesod add-handler functionality doesn't include arguments #898

MaxGabriel opened this Issue Dec 30, 2014 · 1 comment


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MaxGabriel commented Dec 30, 2014

Currently, the add-handler command from yesod-bin doesn't include arguments in the function implementation:

yesod add-handler
> Foo
> /test/#UserId
module Handler.Foo where

import Import

getFooR :: UserId -> Handler Html
getFooR = error "Not yet implemented: getFooR" -- no function argument here

While not necessary, it'd be nice if getFooR included the arguments:

getFooR :: UserId -> Handler Html
getFooR userId = error "Not yet implemented: getFooR"

I was thinking just lowercasing the first letter of the type would do it, i.e. UserId => userId. This doesn't work as well for generic types like Text (text), but seems better than nothing.

This would avoid a compiler error if you implement the function without the argument by mistake, reduces boilerplate, and promotes more consistent argument naming (e.g. BlogPostId consistently becomes blogPostId rather than blogpostId).

One issue with this approach is that people would get warnings for unused arguments. In this case, using underscores might be the best alternative:

getFooR :: UserId -> Handler Html
getFoorR _ = error "Not yet implemented: getFooR"

edit: or with a prefixed underscore

getFooR :: UserId -> Handler Html
getFoorR _userId = error "Not yet implemented: getFooR"

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snoyberg Dec 31, 2014


Addressed by pull request


snoyberg commented Dec 31, 2014

Addressed by pull request

@snoyberg snoyberg closed this Dec 31, 2014

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