Very good questions, answers below.
On Thu, Dec 30, 2010 at 1:01 PM, Iustin Pop
Hi all,
I just started looking at Yesod and its associated libs (hamlet, etc.) and it is very interesting, thanks.
However, I'm confused by a few things and the docs are not helping, so please bear my beginner questions.
First: hamlet uses '.' as function application, instead of the usual space. How can I then use a qualified name (e.g. Data.List.nub)? If I use it normally, it errors out on me. Must be something very trivial but I cannot find a way.
Hamlet uses both '.' and space as function application, and therefore qualified names are not supported. I work around this usually by creating an alias for the function I want locally. I know this can be inelegant; if you have any ideas, I'm all ears.
Second: Yesod.Json says “Due to the limited nature of the JSON format, you can create any valid JSON document you wish using only jsonScalar, jsonList and jsonMap”. This seems false to me, as jsonScalar only deals with JSON strins, and not JSON numbers or the constants (true, false, null). In the meantime I'm using a hack for numbers using jsonRaw, but I think some more functionality needs to be added to it for non-trivial usage.
Quite correct. I'm working on Yesod 0.7 right now, which will be offloading the JSON work to John Millikin's json-types package which properly supports numbers, booleans and nulls.
And last: I don't understand how runDB and the persistent framework is supposed to do error handling. Case in point: let's say one tries to insert a duplicate unique key in a table, which fails as expected "user error (SQLite3 returned ErrorConstraint while attempting to perform step.)". The problem is any other use of that particular REST resource, even with different parameters, results in "user error (SQLite3 returned ErrorMisuse while attempting to perform bind text.)", and I don't know if this is due to my usage of the framework or due to something else. The interesting part is that other resources are working fine.
That sounds like a bug in the SQLite backend to be honest. Could you send me a test case that breaks it? It is much appreciated. Michael