Mattias Bengtsson wrote:
Currently i'm working, together with a friend, on an abstraction (sort
of) of HaskellDB for a school-project.
Basically we are generating haskell-modules similar to those generated
by DBDirect in HaskellDB together with some helpers for the most common
queries you'd want to run.
HaskellDB has its own record system (HDBRec) and a HaskellDB-query also
returns such a record. The accessor-functions for these records can
later be found in DatabaseName.TableName.ColumnName.column. These should
be imported qualified to avoid name clashes.
This is some example code:
students <- School.Students.all db
mapM_ printStudentId students
printStudentId rec = print $ rec!School.Students.Id.column
The main problem for me here is this part:
rec!School.Students.Name.column
where i would rather just write
rec!id
This isn't possible and the other way is just too messy for my taste. It
simply isn't the easy and nice syntax i had hoped for when we started to
develop this.
Are there any other nice substitutes for HDBRec or normal haskell
records that i could use that doesn't make name clashes an issue?
Mattias
It's not perfect, but you can make it a lot shorter by importing the
modules that declare the fields with shorter names:
import qualified School.Students as Students
import qualified School.Students.Name as Name
students <- Students.all db
mapM_ printStudentId students
printStudentId rec = print $ rec!Name.column
But the right answer, I'm afraid, is that there is no really nice way to
work with records in today's Haskell.
You may want to have a look at HList [1] to see if that works better. If
it does, you are very welcome to port HaskellDB to use it instead of HDBRec.
/Björn
[1] http://homepages.cwi.nl/~ralf/HList/
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