[Haskell-cafe] ANN: nice-html, an all-around "nice" html templating library, similar but different to lucid, blaze, type-of-html, etc.

[Oleg Grenrus]

Please, if you think blaze-markup violates the Monad laws, then report a
counterexample so it will get fixed.

The changelog for 0.8.0.0 [1] advertises: Make `MarkupM` finally adhere
to the Monad laws

http://hackage.haskell.org/package/blaze-markup-0.8.0.0/changelog

Cheers, Oleg.


On 26.10.2017 16:54, Mike Ledger wrote:
> >Do you mind explaining the invalid monad instance of Lucid and how it
> would impact a library user?
> To my knowledge lucid uses a monad instance that follow the monad laws
> (what I meant by "valid") fine.
>
> It's blaze that's (somewhat) infamous for having an invalid monad
> instance. It used to be the case that (>>=) in blaze called 'error' --
> the Monad instance was to just use (>>) = mappend. Looking now, the
> implementation has changed and my knowledge was out-of-date. I think
> it still violates the monad laws, but I don't know if as a user of
> blaze you'd ever be able to actually observe this, if that makes any
> sense.
>
> For some fun discussions on this see:
> -
> https://stackoverflow.com/questions/6399648/what-happens-to-you-if-you-break-the-monad-laws
> -
> https://www.reddit.com/r/haskell/comments/16iakr/what_happens_when_a_monad_violates_monadic_laws/
>
> How invalid monads /can/ impact users is better explored in the SO
> question.
>
> >Also, I'm assuming one shouldn't call the `compile` function each
> time a page needs to be rendered, right? Should one put the results of
> the `compile` function in a top-level Map and use those to get the
> speed gains?
> The idea is to only compile a template once, ever. If you need to
> compile a template every time a page is rendered (though I can't
> actually think of a case where you would), you should probably just
> skip the middle-man, and use lucid (or blaze). It's not horribly slow,
> but you'd miss out on the benefits of nice-html by doing this.
>
> Cheers
>
> On Thu, Oct 26, 2017 at 11:51 PM, Saurabh Nanda
> <saurabhnanda at gmail.com <mailto:saurabhnanda at gmail.com>> wrote:
>
>     Thank you for putting comparisons and benchmarks, upfront.
>
>     Do you mind explaining the invalid monad instance of Lucid and how
>     it would impact a library user?
>
>     Also, I'm assuming one shouldn't call the `compile` function each
>     time a page needs to be rendered, right? Should one put the
>     results of the `compile` function in a top-level Map and use those
>     to get the speed gains?
>
>     Side comment, the use of `dynamic` makes it look similar to reflex
>     `dyn*` API.
>
>     -- Saurabh.
>
>     On Thu, Oct 26, 2017 at 4:15 PM, Mike Ledger
>     <eleventynine at gmail.com <mailto:eleventynine at gmail.com>> wrote:
>
>         Hi Haskell-Cafe,
>
>         I've been working on and off on a HTML templating library that
>         is slightly novel for a few months. 
>
>         Here's the good parts:
>         * it's faster than lucid and blaze
>         * it has a valid monad instance
>         * it has another valid monad instance, that is slightly different!
>         * it paramaterises templates by the data they require
>         * the HTML5 combinators don't rely on any highly
>         overloaded/overlapping typeclasses; type errors in nice-html
>         templates tend to be nice monomorphic type mismatches
>
>         To achieve this, it has a distinct compilation phase (at
>         runtime) for templates. This means the actual rendering
>         function does very little beyond concatenate Text and escape
>         dynamic input. It also severely restricts usage to the
>         built-in combinators available -- at least, for dynamic data
>         -- and can make writing a nice-html template difficult, though
>         littering _ throughout type signatures helps.
>
>         Check it out!
>
>         Benchmark results, a README, and an example:
>         https://github.com/TransportEngineering/nice-html
>         <https://github.com/TransportEngineering/nice-html>
>         Hackage: https://hackage.haskell.org/package/nice-html
>         <https://hackage.haskell.org/package/nice-html>
>
>         The only thing on the roadmap right now is to have some nice
>         :-) way to assign JavaScript event handlers to Markup. This is
>         something that I really appreciate when using React.js, so my
>         eventual aim is for nice-html to be like a (more) server-side
>         version of React. Right now, you can keep track of element ids
>         with `Text.Html.Writer.note`, but it's neither a very good nor
>         very useful interface.
>
>         Cheers,
>         Mike
>
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>
>
>
>     -- 
>     http://www.saurabhnanda.com
>
>
>
>
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