[Haskell-cafe] Re: Finally tagless and abstract relational Algebra

Günther Schmidt gue.schmidt at web.de
Tue Dec 29 11:37:24 EST 2009

Hello Kim-Ee,

well right now I would even go for an abstract comprehension DSL.

I do think there's a big difference between the various DSL techniques, 
most are designed with a particular evaluation in mind, tagless-style 
ones are focused on constructing typed terms first, and the evaluation / 
compilation is somewhat detached from that.


Am 29.12.09 14:36, schrieb Kim-Ee Yeoh:
> Günther Schmidt wrote:
>> Initially I had simply imported the CSV files into empty tables in a
>> database and done the calculations directly in SQL, never ever again!
>> [snip]
>> But my 1st goal here is to express the algorithm.
> Sounds like you want a better DSL than SQL. You're in massive company.
> Conal gives a lot of useful advice on DSL design.
> One way to start is to articulate existing pain. Where and why is SQL
> painful?
> Another trick is to work backwards: What kind of code do you really want to
> write?
> Whether you employ GADTs, initial datatypes, finally-tagless codata, etc.
> isn't
> really relevant at this stage. Prematurely latching on to a particular tool
> gets
> everything treated like a nail, even when they're nowhere close.

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