[web-devel] Esqueleto error messages

Erik de Castro Lopo mle+hs at mega-nerd.com
Thu Oct 25 02:32:36 CEST 2012

Hi all (and in particular Filipe),

I'm looking at Esqueleto and I'm finding that in certain circumstances
it can throw out some rather horrid error messages. Consider the correct
code fragment taken from the Esqueleto docs:

    select $
        from $ \(b, p) -> do
            where_ (b ^. BlogPostAuthorId ==. p ^. PersonId)
            return (b, p)

The error occurs if the programmer uses the wrong identifer in the where_
clause. For instance, if PersonId is used instead of BlogPostAuthorId
then I get about 100 lines of error message, the majority of which is
totally incomprehensible.

Is there anything that can be done inside Esqueleto to make these error
messages better?

Erik de Castro Lopo

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