Re: [Haskell-cafe] "Write Yourself a Scheme in 48 Hours"

[Shannon -jj Behrens]

On 2/1/07, Bryan O'Sullivan <[EMAIL PROTECTED]> wrote:

Shannon -jj Behrens wrote:
> I'm going through the "Write Yourself a Scheme in 48 Hours"
> 
>
> tutorial.  I like it a lot, but I have some concerns.  Are the
> exercises in the tutorial known to be solvable by mere mortals?

The answer seems to be "yes, iff the mortals in question have grasped
the basics of monads, so they can fill in the gaps in the exposition."

> For instance:
>
> "Rewrite parseNumber using...explicit sequencing with the >>= operator"
> 
http://halogen.note.amherst.edu/~jdtang/scheme_in_48/tutorial/parser.html#symbols
>
> There aren't any examples of using >>= previous to this question.

There's a peculiar mixture of assumptions in the article.  He treats
monads breezily, as if they're a given; but pattern matching (much more
basic) receives some rather more detailed exposition.  And he glosses
over ">>", but doesn't mention the rewrite rule from "a<-x" to "x>>=\a->".

So don't beat yourself up.  The tutorial is missing a few bits and pieces.


Thanks.  That's all I needed to hear :)

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Re: [Haskell-cafe] "Write Yourself a Scheme in 48 Hours"

[Henk-Jan van Tuyl]

See for examples of the usage of >>= "A tour of the Haskell monad  
functions", URL:

  members.chello.nl/hjgtuyl/tourdemonad.html


On Fri, 02 Feb 2007 01:31:36 +0100, Shannon -jj Behrens <[EMAIL PROTECTED]>  
wrote:



I'm going through the "Write Yourself a Scheme in 48 Hours"

tutorial.  I like it a lot, but I have some concerns.  Are the
exercises in the tutorial known to be solvable by mere mortals?

For instance:

"Rewrite parseNumber using...explicit sequencing with the >>= operator"
http://halogen.note.amherst.edu/~jdtang/scheme_in_48/tutorial/parser.html#symbols

There aren't any examples of using >>= previous to this question.
Furthermore, the link to the Standard Prelude is not helpful because
there aren't any examples of how to use >>=.


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Met vriendelijke groet,
Henk-Jan van Tuyl


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Re: [Haskell-cafe] "Write Yourself a Scheme in 48 Hours"

[Bryan O'Sullivan]

Shannon -jj Behrens wrote:

I'm going through the "Write Yourself a Scheme in 48 Hours"
 


tutorial.  I like it a lot, but I have some concerns.  Are the
exercises in the tutorial known to be solvable by mere mortals?


The answer seems to be "yes, iff the mortals in question have grasped 
the basics of monads, so they can fill in the gaps in the exposition."



For instance:

"Rewrite parseNumber using...explicit sequencing with the >>= operator"
http://halogen.note.amherst.edu/~jdtang/scheme_in_48/tutorial/parser.html#symbols 


There aren't any examples of using >>= previous to this question.


There's a peculiar mixture of assumptions in the article.  He treats 
monads breezily, as if they're a given; but pattern matching (much more 
basic) receives some rather more detailed exposition.  And he glosses 
over ">>", but doesn't mention the rewrite rule from "a<-x" to "x>>=\a->".


So don't beat yourself up.  The tutorial is missing a few bits and pieces.

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