[web-devel] Yesod beginner

anthropornis anthropornis at gmail.com
Thu Jun 16 16:23:34 CEST 2011

(I forgot to mention earlier, I'm also new to Haskell, sorta starting 
with Yesod first to just get something running, then going on to 
learning Haskell, so I can get rid of a PHP CRUD interface for an 
existing db.)

I tried cabal install without any flags and it eventually worked.

Initially cabal yielded this error:
     cabal: Error: some packages failed to install:
     HDBC-postgresql- failed during the configure step. The 
exception was:
     ExitFailure 1
     persistent-postgresql-0.5.0 depends on HDBC-postgresql- 
which failed to install.
     sample-0.0.0 depends on HDBC-postgresql- which failed to 

Reading further up in the terminal output I saw something mentioned 
about one package needing to be installed for server side extensions, or 
libpq-dev needing to be installed for client side applications.

I took a chance that libpq-dev would be the right choice and installed 
it, then ran cabal install again, and this time it worked, and I was 
able to launch the dev server.

Viewing the page in my web browser I attempted to add an email login, 
but nothing happened. Switching back to the terminal it said sendmail 
needed to be installed. After installing sendmail I was able to create a 

I had one question about sendmail. I noted somewhere else in your docs 
that I could possibly do something like Adobe AIR (?) and make an 
executable with Webkit in it as an offline version of the web app (which 
would be really cool, by the way).  I wasn't sure, if I put that 
executable on someone's Windows machine, is sendmail available for 
Windows or can the email pieces be switched with something other than 
sendmail if needed?

Thanks again

On 06/15/2011 10:52 PM, Michael Snoyman wrote:
> On Thu, Jun 16, 2011 at 12:46 AM, anthropornis<anthropornis at gmail.com>  wrote:
>> Hello,
>> I was following the "Yesod in Five Minutes Instructions" and I had a couple
>> of bumps in the road.
>> The first one was when trying to do step 6, I get the following terminal
>> output:
>>     unrecognized option `--only-dependencies'
>> After ignoring that for the moment, I proceeded to trying to run the devel
>> server and I get this terminal output:
>>     yesod: user error (At least the following dependencies are missing:
>>     persistent-postgresql ==0.5.*)
>> I'm guessing the second error may be related to the first, maybe
>> persistent-postgresql was one of those dependencies that was supposed to be
>> installed?
>> I did create the Postgres databases and user specified in the Yesod app
>> config file.
>> I'm using this PPA on Ubuntu 11.04 64-bit, as the repo version of the
>> Haskell Platform seems to be broken:
>>     https://launchpad.net/~brcha/+archive/ppa
>> Thanks for any insight.
> Try just plain "cabal install", the "--only-dependencies" is available
> in newer versions of the "cabal" tool. I'm going to remove it from the
> docs.
> Michael

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