- web-devel - Haskell.org

Yesod Resources
by Steven Leiva 01 Mar '26

01 Mar '26

Are you aware that there is a book dedicated to Yesod: https://www.yesodweb.com/book Is that not sufficient? I’d be happy to try and contribute “addendums” if there are things you want to do that are not spelled-out in the book. But yes, Yesod is the Laravel of Haskell - i.e., batteries included web development framework. On February 26, 2026 at 11:00:16 PM, web-devel-request(a)haskell.org ( web-devel-request(a)haskell.org) wrote: Send web-devel mailing list submissions to web-devel(a)haskell.org To subscribe or unsubscribe via email, send a message with subject or body 'help' to web-devel-request(a)haskell.org You can reach the person managing the list at web-devel-owner(a)haskell.org When replying, please edit your Subject line so it is more specific than "Re: Contents of web-devel digest..." Today's Topics: 1. Let's make Haskell Great Again (parables95(a)proton.me) ---------------------------------------------------------------------- Message: 1 Date: Thu, 26 Feb 2026 17:11:40 -0000 From: parables95(a)proton.me Subject: [web-devel] Let's make Haskell Great Again To: web-devel(a)haskell.org Message-ID: <177212590098.8195.8417764738795112466@localhost> Content-Type: text/plain; charset="utf-8" My first time with PHP was through Laravel 5 and since then, I have built production scale apps and loved the PHP language. In Haskell's world, it seems like Yesod is the Laravel here. But getting started isn't easy and there isn't much resources out there to guide newbies. Let's change that. ------------------------------ Subject: Digest Footer _______________________________________________ web-devel mailing list -- web-devel(a)haskell.org To unsubscribe send an email to web-devel-leave(a)haskell.org ------------------------------ End of web-devel Digest, Vol 77, Issue 2 ****************************************

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Let's make Haskell Great Again
by parables95＠proton.me 26 Feb '26

26 Feb '26

My first time with PHP was through Laravel 5 and since then, I have built production scale apps and loved the PHP language. In Haskell's world, it seems like Yesod is the Laravel here. But getting started isn't easy and there isn't much resources out there to guide newbies. Let's change that.

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haskell memory allocation
by anaaugusto2012＠bol.com.br 25 Sep '19

25 Sep '19

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ToWidget instances for Text and friends
by Andrew Martin 27 Nov '16

27 Nov '16

I have copied the body of this github issue get feedback on this suggestion: https://github.com/yesodweb/yesod/issues/1298 The ToWidget typeclass could be more helpful than it currently is. Notably, there are sensible instances for Text, lazy Text, and text Builder that are not provided. I think that one objection to introducing such classes is that there is a piece of syntax in the shakespeare quasiquoter ^{..} that calls ToWidget on its argument. Adding more instances would allow the end user to feed text into this construct, which might be undesirable. I don't use the quasiquoter for templating, so the downside of it doesn't bother me. The reason I would like these instances is because there are a number of situations where I have to call `toWidget . toHtml` in my code that could be abbreviated to toWidget if these instances were provided. If this change is at odds with the goals of the TH templating, then I wouldn't want to mess that up for people, but if not, I would find these instances useful. I would appreciate any feedback, even if it's just in the form of a +1 or -1 response without any further explanation. -Andrew Martin

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Feedback request: new Yesod development server
by Michael Snoyman 24 Nov '16

24 Nov '16

Hey all, I've just published a blog post describing an (almost total) rewrite of the `yesod devel` server: http://www.yesodweb.com/blog/2016/11/new-yesod-devel-server This new version is not yet released, I'm requesting feedback before doing so. If people can have a look, I'd appreciate it. I'm including the web-devel list, since this new version has very explicit documentation on how to use `yesod devel` with non-Yesod application. Michael

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[ANN] servant 0.5
by Julian Arni 19 Mar '16

19 Mar '16

Dear all, We have just released a new major version (0.5) of the official servant packages: - servant - servant-server - servant-client - servant-docs - servant-foreign - servant-js - servant-cassava - servant-blaze - servant-lucid - servant-mock (servant-js and servant-foreign are being released for the first time. servant-jquery will be deprecated in favour of servant-js) This new version brings quite a number of significant changes. Servant is now faster, more correct, more replete with features, and more consistent. We have a blog post going into more details about the changes: http://haskell-servant.github.io/posts/2016-03-19-servant-0.5-release.html Note also that we have revamped our tutorial, and moved it to readthedocs: http://haskell-servant.readthedocs.org/en/master/ Enjoy the weekend, Julian

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Keep too busy crawlers away from your server
by Henning Thielemann 01 Mar '16

01 Mar '16

I know there are more sophisticated tools for that task, but I wrote a pretty simple program that works for me reliably for several months now. See the attached program. It scans the last 100 KB of a log-file you specify as command-line argument and checks whether certain clients excess allowedAccessesPerSecond. If so, their IPs are written to a blocked-hosts file and are removed from there only 5 days later. The blocked-hosts file in my example is used by arno-iptables-firewall to actually block the IP addresses. I added this program to my crontab: # m h dom mon dow command * * * * * process-log /var/log/http-access.log >>/var/log/http-block.log 2>>/var/log/http-block.err

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HTTP Status with Streaming Request Bodies
by Mark Fine 29 Feb '16

29 Feb '16

I'm running into a problem handling requests with streaming request bodies that fail - using http-client, the failure takes a long time (potentially never) to propagate. Simple code (runnable project here <https://github.com/mfine/streamy>): {-# LANGUAGE OverloadedStrings #-} import Control.Monad import Data.Conduit.Combinators import Network.HTTP.Conduit import System.Environment a :: IO () a = do manager <- newManager tlsManagerSettings request <- parseUrl "http://httpbin.org/status/409" void $ httpLbs request manager b :: IO () b = do manager <- newManager tlsManagerSettings request <- parseUrl "http://httpbin.org/status/409" void $ flip httpLbs manager request { requestBody = requestBodySourceChunked $ repeatM $ return "a" } Running "a" above works as expected (propagating the error immediately). Running "b" has variable results, mostly never propagating the error. Looking at the wire, I can see that the 409 status comes back, but the exception does not propagate. Is there something I can do here to get quicker failure? Thanks! Mark

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path to sendmail
by Jeremy Shaw 09 Feb '16

09 Feb '16

Hello, I have a web application which needs to send mail using sendmail. However, the way the system is configured, sendmail is not in the web server's $PATH. There are two fixes for this -- change the init script so that sendmail is in the $PATH -- or modify the web server so that the admin can set the path to sendmail via the control panel. At first the second option sounds good. But I wonder about the security implications. If someone manages to get the password for the admin control panel -- they could change the path to sendmail to something else -- like `vim` or `gcc` and then somehow craft a message that would place a backdoor on the system. Now, given that the input to the message is going to be a mime message that sounds pretty difficult. But, then again, in December tons of Joomla sites were open to an exploit where a malformed user-agent header allowed hackers to execute arbitrary code. Although in this case I care about sendmail, this is clearly an issue for any web application that depends on external binaries like pandoc, etc. In my use case, I am dealing with a CMS and I assume the poor user doesn't know anything about Haskell, init scripts, ssh, etc. So, allowing the location to be changed via the admin panel makes things easier because it can be adapted to any distribution. (Clearly, I would start by checking the most common locations, but provide an escape hatch for oddballs). But I don't like the idea of providing a potential attack vector. Any thoughts ? - jeremy

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Announcing serversession
by Felipe Lessa 01 Jan '16

01 Jan '16

Hey! These packages have been available for a while but only now I've finally publicly announced their availability. Please see my blog post at http://blog.felipe.lessa.nom.br/?p=153, but feel free to reply back here. Happy New Year! -- Felipe.

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