[Haskell-cafe] A question on DSL's

[Luke Palmer]

On Mon, Jan 4, 2010 at 12:16 PM, Tom Hawkins <tomahawkins at gmail.com> wrote:
> One argument for option 2 is to carry forward datatypes to the target
> language.  For example, if you want to describe a state machine with
> the state as a type:

What do you mean "carry forward".  Can you elaborate on your simple
example?  What about it requires option 2?

>
> data StopLightState = Red | Yellow | Green
>
> With option 1, values of type StopLightState will be resolved at
> compile-time, not run-time.  (yes, there's tricks to get around this,
> but they're ugly)
>
> I experimented briefly with option 2 using YHC, but quickly threw in
> the cards for option 1.
>
> It would be nice if GHC's internals were more accessible for this type of work.
>
>
>
> On Mon, Jan 4, 2010 at 6:20 PM, Jasper Van der Jeugt
> <jaspervdj at gmail.com> wrote:
>> Hello,
>> I see no real reason to use the second approach, unless you're doing
>> something tremendously new and big. Besides, the first solution is much
>> easier and will be easier to maintain (in case the back end changes).
>> Kind regards,
>> Jasper Van der Jeugt
>>
>> On Mon, Jan 4, 2010 at 6:14 PM, CK Kashyap <ck_kashyap at yahoo.com> wrote:
>>>
>>> Hi,
>>> I am not sure if I'm using DSL in the right context here but I am
>>> referring to those solutions that allow us to write code in Haskell and
>>> generate a target code source code of another language or even object code
>>> for that matter. I am aware of two ways of achieving this -
>>> 1. Implement functions that emit the target code - that is, when the
>>> Haskell code is compiled and run, the target code is emitted
>>> 2. Modify the Haskell compiler's back end to emit the code - that is when
>>> the Haskell code is compiled the target code is emitted
>>>
>>> I am not sure if there are more ways (hybrid perhaps) ...
>>>
>>> My question is,  when would I chose one approach over the other?
>>>
>>> Regards,
>>> Kashyap
>>>
>>>
>>>
>>>
>>>
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>>
>>
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