Not Lisp again....

http://funcall.blogspot.com/2009/03/not-lisp-again.html

by spydez • 17 years ago

178 39 17 years ago

funcall.blogspot.com

brlewis2• 17 years ago

I loved this same course (spring '87 for me), but I wasn't impressed with the speed. I came away thinking Scheme was for fun and C was for practical programming. I've come around since then, and I don't have any performance concerns about my Scheme-based web site.

antiismist2• 17 years ago

What is your scheme-based website? Is it ourdoings or something else? Just curious because there aren't a lot of them out there that I know of.

brlewis2• 17 years ago

OurDoings is it. I still use the "wishful thinking" programming methodology I learned from SICP. I'm married with 3 kids and a separate day job, and don't think I could have pulled this off using a less programmable programming language.

rlm2• 17 years ago

This is the essence of that "This is so cool"-feeling that arises when you first really _get_ programming.

And almost makes me want to invest in SICP or something similar to see what all this LISP-talk is about :)

lliiffee• 17 years ago

Read the full text online right now:

http://mitpress.mit.edu/sicp/full-text/book/book.html

If you meant an investment of time, then, well yes. But SICP is really, really fun.

rlm2• 17 years ago

I both meant an investment of time and money :)

I don't like reading entire books on the computer. It just feels better on paper ;)

chrisconley• 17 years ago

Don't forget about our Hacker News SICP Book Club too: http://groups.google.com/group/hacker-news-reads-sicp

michael_dorfman• 17 years ago

....and don't forget the SICP video lectures! http://groups.csail.mit.edu/mac/classes/6.001/abelson-sussma...

The best 20-hour introduction to CS you can find, or your money back!

gamache• 17 years ago

And Hal Abelson knows how to give fledgling programmers that Eureka moment in spades. This article mirrors my experiences very closely -- I came into the class Spring 1998 with BASIC and assembly experience, thinking I knew how to program.

SICP couldn't be worth any more if it were printed on gold leaf, but having Abelson and Sussman there to teach it really seals the deal.

coffeemug2• 17 years ago

You know, if you keep learning you will never cease to have this feeling.

  ?- append([1, 2, 3], [4, 5, 6], X).
  X = [1, 2, 3, 4, 5, 6].

  ?- append([1, 2, 3], X, [1, 2, 3, 4, 5, 6]).
  X = [4, 5, 6].

  ?- append(X, [4, 5, 6], [1, 2, 3, 4, 5, 6]).
  X = [1, 2, 3].

And the definition of append:

  append([], X, X).
  append([X | Y], Z, [X | O]) :- append(Y, Z, O).

Magic!

moe2• 17 years ago

What is this snippet supposed to tell me? Looks completely meaningless to me.

anatoly• 17 years ago

Ah, thank you for rekindling that memory.

Prolog, where you just type what you want to achieve, and it goes ahead and does it for you. I really couldn't wrap my head around it for some time. I read up on backtracking and chased around derivations on paper to satisfy myself that something like append really worked.

Hexstream• 17 years ago

You mean if one keeps learning after SICP? Bad example, because SICP tells you how to implement exactly this functionality (among other things).

jjames• 17 years ago

Wish there was a way to read this online but The Little Schemer http://www.ccs.neu.edu/home/matthias/BTLS/ made the first couple chapters of SICP a little easier for self study.

discojesus• 17 years ago

there is (sort of); it's available nearly in its entirety on Google Books.

sanj• 17 years ago

Summary: tail recursion FTW!

http://en.wikipedia.org/wiki/Tail_recursion

sketerpot2• 17 years ago

This belongs in the summary: {higher-order functions, closures, potentially-inefficient elegance} FTW.

jeeringmole• 17 years ago

An excellent recent book is Peter Seibel's Practical Common Lisp. http://www.gigamonkeys.com/book/ The approach is what you might guess from the title, so it addresses both the fun of Lisp and the building of practical applications (including web apps).

elai• 17 years ago

Hey you can do this w/ python too!

<code> dx = .000001

def deriv(f): def fprime(x): return (f(x+dx) - f(x))/dx return fprime

def cube(x): return x3

def printDeriv(x): print (deriv(cube))(x) print 3x*2

printDeriv(5) </code>

sketerpot2• 17 years ago

In general, you can do this in any language which lets you pass functions around as values, and which supports closures. And languages in which you can fake it somehow.

gaius• 17 years ago

Start a line with 4 spaces, rather than using <code> tags.

diN0bot• 17 years ago

the four concerns the author lists at the end are interesting for what they say about where he's coming from. to me, the joy of programming is more about programming than speed or efficiency.

that he also put 'harder to understand' and 'capability' in the list is confusing. he must mean capability in some kind of raw sense, whereas i see capability as having abstraction and libraries so i can get to the meat faster. again, abstraction is usually easier to understand.

perhaps when meat is speed and efficiency then our perspectives merge. psyched about 16 Mb of RAM!

btw, scheme has recently been replaced by python in the intro programming courses. snap.

kragen• 17 years ago

Read the previous post where he was introduced to Lisp by way of MACRO-11, and you'll see what he means by "capability".

ced• 17 years ago

Funny how tail recursion pretty much has "cute optimization hack" written all over it. It really doesn't feel at home in a first lecture on programming.

dfox• 17 years ago

Tail recursion has profound theoretical implications, so it belongs there. If your language is properly tail-recursive it completely changes definition of recursive and iterative.

ShardPhoenix• 17 years ago

That derivative example is nice, but it reinforces that Lisp is a bit too "pure"/"mathy" for my taste (that and I really don't like the syntax). My equivalent of that derivative thing was probably the examples in "Why's Poignant Guide to Ruby", pretty syntax-highlighting colors and all.

dbul• 17 years ago

Interesting first lecture. I think the great Oscar Waddell (a wizard though no longer in academia to my knowledge) wrote a Scheme program centered around beer for our first lecture at IU. Now that caught the attention of many students and I'm pretty sure the class /grew/ in size for the next lecture.

Not Lisp again....

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