Re: Is DSSSL Syntax Tricky?

Subject: Re: Is DSSSL Syntax Tricky?
From: lee@xxxxxx
Date: Tue, 20 May 97 22:36:25 EDT
Paul Prescod waxed lyrical about map...

And I recall that I used to have a shell programming guide for
Unix System 4.1 (never released -- nothing to do with BSD 4.1) that
used "map" as a simple example shell script.

Anyone who wants some examples of map and other Scheme functions and
techiques should go and buy two awfully thin books from the MIT press,
the Little Schemer and the Seasoned Schemer.  Or come on one of our
Sculptor/Scheme courses and get given a copy :-) :-)

It's much easier to learn Scheme with some good clear examples.

Also use an editor that balances parentheses... e.g. emacs, or vi in
lisp more (:set lisp) (not implemented in most of the free versions of vi)
as otherwise you're making life much too difficult!

> Any time you need to do something to all elements of a list, node-list
> or string, you can convert it to a list, write a little function that
> does the "thing", use the function as the first argument and the list
> as the second, map will return a list.
It's also common in Scheme to use an anonymous function there, with lambda:
     (lambda (x) (+ x 3))
     (list 1 2 3 4))
    '(3 5 6 7)

DSSSL has lambda expressions ( although I don't know if the
syntax is there in Jade (and can't try from here, sorry!).

It is easy to write very short fragments of scheme that are very hard to
understand using this paradigm.  Use plenty of comments!  Use long, long
identifiers.  It's excellent that the DSSSL standard is so clearly
written and follows this model.


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