On 12 Mar 2009, at 15:33, Colin Paul Adams wrote:
"Thomas" == Thomas Davie <[email protected]> writes:
Thomas> On 12 Mar 2009, at 15:16, Andrew Wagner wrote:
Can you expand on this a bit? I'm curious why you think this.
Thomas> For two reasons:
Thomas> Firstly, I often find that people use the Monadic
Thomas> interface when one of the less powerful ones is both
Thomas> powerful enough and more convenient, parsec is a wonderful
Thomas> example of this. When the applicative instance is used
Thomas> instead of the monadic one, programs rapidly become more
Thomas> readable, because they stop describing the order in which
Thomas> things should be parsed, and start describing the grammar
Thomas> of the language being parsed instead.
That's interesting.
I recently used parsec 3. I wrote using the monadic interface because
I could understand (just about) how to do so. I was looking at the
examples in RWH, and I could follow the explanation of the monadic
interface much easier.
Perhaps this was because RWH shows how to write using the monadic
interface, and then shows how to convert this to the applicative
interface.
It's hard to follow a tutorial that shows you how to convert from
something you aren't starting with.
I suspect that this is an interesting corner case of both my two
reasons – firstly, Monads are too powerful here, and secondly, you
perhaps found it easier to think about the operational aspects of the
parser than to think about the denotation of what the parser should
parse.
Is that somewhere accurate?
Bob_______________________________________________
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