reading file to list

nick_keighley_nospam at hotmail.com nick_keighley_nospam at hotmail.com
Wed Feb 25 12:34:33 CET 2009


On 17 Jan, 17:16, Xah Lee <xah... at gmail.com> wrote:
> comp.lang.lisp,comp.lang.scheme,comp.lang.functional,comp.lang.python,comp.­lang.ruby

<snip>

> The lisp's cons fundamentally makes nested list a pain to work with.
> Lisp's nested syntax makes functional sequencing cumbersome.

so hide it

(define (make-list stream eos?)
    (let ((atom (stream)))
        (if (eos? atom)
            '()
            (cons atom (make-list stream eos?)))))

(define (make-int-list port)
    (make-list (lambda () (read-line port)) null?))

the nasty cons then only appears in a single function which
you can hide in a library


> In the ruby code, its post-fix sequential notation (as a side effect
> of its OOP notation) brings out the beauty of functional sequencing
> paradigm (sometimes known as functional chain, sequencing, filtering,
> unix piping).
>
> its list, like all modern high level langs such as perl, php, python,
> javascript, don't have the lisp's cons problem. The cons destroys the
> usability of lists up-front, untill you have some at least 2 full-time
> years of coding lisp to utilize cons properly. (and even after that,
> it is still a pain to work with, and all you gain is a bit of speed
> optimization in rare cases that requires largish data, most of which
> has better solutions such as a database.)

is my code to build a list that bad?


> Both of these problems i've published articles on.
>
> For more detail on the cons problem, see
> the section “The Cons Business” at
>
> • Fundamental Problems of Lisp
>  http://xahlee.org/UnixResource_dir/writ/lisp_problems.html

I read it. Your point seems to be "cons becomes difficult
with deeply nested structures". Could you give an example?



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