From 562a9a52d599d9a05f871404050968a5fd282640 Mon Sep 17 00:00:00 2001 From: elioat Date: Wed, 23 Aug 2023 07:52:19 -0400 Subject: * --- js/games/nluqo.github.io/~bh/v1ch1/explor.html | 449 +++++++++++++++++++++++++ js/games/nluqo.github.io/~bh/v1ch1/v1ch1.html | 449 +++++++++++++++++++++++++ 2 files changed, 898 insertions(+) create mode 100644 js/games/nluqo.github.io/~bh/v1ch1/explor.html create mode 100644 js/games/nluqo.github.io/~bh/v1ch1/v1ch1.html (limited to 'js/games/nluqo.github.io/~bh/v1ch1') diff --git a/js/games/nluqo.github.io/~bh/v1ch1/explor.html b/js/games/nluqo.github.io/~bh/v1ch1/explor.html new file mode 100644 index 0000000..8b5682b --- /dev/null +++ b/js/games/nluqo.github.io/~bh/v1ch1/explor.html @@ -0,0 +1,449 @@ + + +Computer Science Logo Style vol 1 ch 1: Exploration + + +Computer Science Logo Style volume 1: +Symbolic Computing 2/e Copyright (C) 1997 MIT +

Exploration

+ +

Brian +Harvey
University of California, Berkeley +

Download PDF version +

Back to Table of Contents +

BACK +chapter thread NEXT +

MIT +Press web page for Computer Science Logo Style +

+ +

The name Logo comes from the Greek word logos, which means +"word." In contrast to earlier programming languages, which +emphasized arithmetic computation, Logo was designed to manipulate +language--words and sentences. + +

Like any programming language, Logo is a general-purpose tool that +can be approached in many ways. Logo programming can be understood +at different levels of sophistication. It has been taught to +four-year-olds and to college students. Most of the books about +Logo so far have been introductory books for young beginners, but +this book is different. It's for somewhat older learners, +probably with some prior computer experience, although not +necessarily Logo experience. + +

This book was written using the Berkeley Logo dialect, a version +of Logo that's available at no cost for PCs, Macintoshes, and Unix +systems. Recent commercial Logo +dialects have emphasized the control of real-time animation, +robotics, and other such application areas, somewhat at the +expense of more traditional Logo features designed to be useful +in the development of larger and more complex programs. Berkeley +Logo follows the traditional design, so you may miss some +"bells and whistles" that you associate with Logo from +elementary school. In fact, we'll hardly do any graphics +in this book! + +

Some of the details you'll have to know in order to work with Logo +depend on the particular kind of computer you're using. This +book assumes you already know some things about your computer: + +

How to turn on your computer and start Logo +
How to type a command, ending with the RETURN key +
How to use control keys to correct typing mistakes +
How to use a text editing program +

+ +

+These points I've listed aren't actually part of the Logo +language itself, but they're part of the Logo programming +environment. Appendix A has a brief guide to some of these +machine-specific aspects, but if you've never used a computer before +at all, start by working with some application programs +to get the feel of the machine. + +

On the other hand, I'd like to pretend that you know nothing about +the Logo language--the primitive procedures, the process of +procedure definition, and so on--even if you've really used Logo +in elementary school. The reason for this pretense is +that I want you to think about programming in what will probably be +a new way. The programs may not be new to you, but the +vocabulary with which you think about them will be. I'm warning +you about this ahead of time because I don't want you to skip over +the early chapters, thinking that you already know what's in them. + +

Okay, it's time to start Logo running on your computer. You should +then see a screen that says something like + +

Welcome to Berkeley Logo version 3.3
+?
+

+ +

The question mark is Logo's prompt. When you +see the question mark, it means that the computer is prepared for you +to type in a Logo instruction and that Logo will carry +out the instruction as soon as you finish it. + +

Getting Acquainted with Logo...

+ +

Right now, type this instruction: + +

repeat 50 [setcursor list random 75 random 20 type "Hi]
+

+ +

Remember that square brackets [] are different from +parentheses (). Also remember that it's important to put +spaces between words. However, it doesn't matter whether you use +UPPER CASE or lower case letters in the words that Logo understands. + +

If all goes well, Logo will cheerfully greet you by scattering +His all over the screen. If all doesn't go well, you probably +misspelled something. Take a look at what you typed, and try again. + +

Afterward, you can clear the screen by typing cleartext or +its abbreviation ct. + +

... in Two Senses

+ +

I thought it would be appropriate to start exploring Logo by having +it say hello. You and Logo can get acquainted as you would with +another person. + +

But, of course, the point of the exercise is to get acquainted with +Logo in a more serious sense too. You're seeing what a Logo +instruction looks like and a little bit about what kinds of things +Logo can do. In this first chapter the kind of acquaintance I have +in mind is relatively superficial. I'm trying to get across a broad +sense of Logo's flavor rather than a lot of details. So I'm not +explaining completely what we're doing here. For that reason, the +second chapter will repeat some of the same activities, but I'll +give a more detailed discussion there. + +

Perhaps you've made Logo's acquaintance before, probably through the +medium of turtle graphics. In that first introduction you may have +explored Logo's ability to manipulate text as well as graphics. But +maybe not. Writing a book like this, it's not easy for me to carry +on a conversation with someone I haven't met, so in this +introduction I may be saying too much or too little for your +individual situation. I hope that by the second chapter you and the +other readers will all be ready for the same discussion. + +

If you haven't used Logo before, or if you've used only the part of +Logo that has to do with turtles, look at the instruction I asked +you to type earlier. Think about the different parts of that +instruction, the words like repeat and random and +setcursor. Try to figure out what each one means. Then see +if you can figure out an experiment to decide if you've understood +each word correctly! Later, we'll go over all these details and +you'll learn the "official" explanations. But the kind of +experimenting I'm suggesting isn't pointless. This kind of +exploration may raise questions in your mind, not just about the +meanings of the Logo words but about how they're connected together +in an instruction, or about why a word means just what it +does rather than something a little different. + +

Another Greeting

+ +

Here is a somewhat less "scatterbrained" greeting instruction: + +

repeat 20 [repeat random 30 [type "Hi] print []]
+

+ +

Try that one. Compare it to the one we started with. +Which do you like better? Do you prefer random scattering, or +orderly rows? Perhaps this question will teach you something about +your own personality! + +

Fooling Around

+ +

Then again, maybe you think this is all silly. If so, I'd like to +try to convince you that there are some good, serious reasons for +you to take a lighthearted approach to computer programming, no +matter how serious your ultimate goals may be. + +

There are two aspects to learning how to program in a language like +Logo. One aspect is memorizing the vocabulary, just as in learning +to speak French. If you flip through the reference manual that came +with your Logo,^* you'll find that it's a sort of dictionary, +translating each Logo word into a bunch of English words that +explain it. But the second aspect is to learn the "feel" of +Logo. What kinds of problems does Logo handle particularly well? +What are the examples of programming style that correspond +to the idioms of a human language? What do you do when something +doesn't work? + +

^*If you're using Berkeley Logo, it's in a file +named usermanual (or userman.ual if you're +using a DOS machine) that should be installed along with the Logo +program. The Berkeley Logo reference manual is also an appendix +to Volume 2 of this series.

It is by fooling around with Logo that you learn this second aspect +of the language. Starting with the second chapter of this book, +we'll be going through plenty of dry, carefully analyzed fine points +of Logo usage. But as we progress, you should still be fooling +around, on the computer, with the ideas in the chapters. + +

In fact, I think that that kind of intellectual play is the best +reason for learning about computer programming in the first place. +This is true whether you are a kid programming for the fun of it or +an adult looking for a career change. The most successful computer +programmers aren't the ones who approach programming as a task they +have to carry out in order to get their paychecks. They're the ones +for whom programming is a joyful game. Just as a baseball diamond +is a good medium in which you can exercise your body, the computer +is a good medium in which you can exercise your mind. That's the +real virtue of the computer in education, not anything about job +training or about arithmetic drill. + +

A Slightly Longer Conversation

+ +

The Logo words such as print and random are the names of +procedures, little pieces of computer program that are +"specialists" in some particular task. We are now going to add to +Logo's repertoire by inventing a new procedure named hi. +At the question mark prompt, start by typing this: + +

to hi
+

+ +

The word to here is short for "here's how to." The +name is intended to suggest the metaphor that what +you're doing when you write computer programs is to teach +the computer a new skill. Metaphors like this can be very helpful +to you in understanding a new idea. (Just ask any English +teacher.) I'll point out other metaphors from time to time. + +

Logo should have responded to this instruction by printing a +different prompt character. Instead of the question mark, +you should now see a greater-than sign (>) at the beginning +of the line: + +

? to hi
+>
+

+ +

(Whenever I show an interaction with the computer in this +book, I'll show the part that you're supposed to type +underlined; what the computer prints in response is not +underlined. +But I won't underline when I'm only showing what you type and +not a complete interaction.) This new prompt means that Logo will +not immediately carry out whatever instructions you type; instead +Logo will remember these instructions as part of the new procedure +hi. Continue typing these lines: + +

print [Hi. What's your name?]
+print sentence [How are you,] word first readlist "?
+ignore readlist
+print [That's nice.]
+end
+

+ +

Again, be careful about the spaces and punctuation. After +the last line, the one that just says end, Logo should go back +to the question mark prompt. Now just type + +

hi
+

+ +

on a line by itself. You can carry on a short +conversation with this program. Here's what happened when I tried +it. + +

? hi
+Hi. What's your name?
+Brian Harvey
+How are you, Brian?
+I'm fine.
+That's nice.
+

+ +

If something unexpected happens when you try it, perhaps +you made a typing mistake. If you know how, you can fix such +mistakes using the Logo editor. If not, you'll have a chance to +review that process later, but for now, just start over again but +give the procedure a different name. For example, you can say + +

to hi2
+

+ +

for the second version of hi. + +

»This program pretends to be pretty smart. It carries on a +conversation with you in English. But of course it isn't really +smart. If you say "I feel terrible" instead of "I'm fine," the +procedure cheerfully replies "That's nice" anyway. How else can +you mess up the program? What programming tools would you need to +be able to overcome the "bugs" in this program? + +

(When a paragraph starts with this symbol » it means that +the paragraph asks you to invent something. Often it will be a Logo +program, but sometimes, as in this case, just answers to questions. This is +a good opportunity to take a break from reading, and check on your +understanding of what you've read.) + +

A Sneaky Greeting

+ +

This chapter started as a sort of pun in my mind--the one about +getting acquainted. How should I have Logo introduce itself? I'm +still playing with that idea. Here's another version. + +

to start
+cleartext
+print [Welcome to Berkeley Logo version 3.3]
+type "|? |
+process readlist
+type "|? |
+wait 100
+print [Ha, ha, fooled you!!]
+end
+
+to process :instruction
+test emptyp :instruction
+iftrue [type "|? | process readlist stop]
+iffalse [print sentence [|I don't know how  to|] first :instruction]
+end
+

+ +

The vertical bars are used to tell Logo that you want to +include space characters within a word. (Ordinarily Logo pays no +attention to extra spaces between words.) This is the sort of +grubby detail you may not want to bother with right now, but if you +are a practical joker you may find it worth the effort. + +

A Quiz Program

+ +

Before we get on to the next chapter, I'll just show you one more +little program. Try typing this in. As before, you'll see +greater-than prompts instead of question marks while you're doing +it. + +

to music.quiz
+print [Who is the greatest musician of all time?]
+if equalp readlist [John Lennon] [print [That's right!] stop]
+print [No, silly, it's John Lennon.]
+end
+

+ +

You can try out this procedure by typing its name as an +instruction.^* + +

^*It has been suggested by some reviewers of the +manuscript that there may be younger readers who don't know who John Lennon +is. Well, he's the father of Julian Lennon, an obscure rock star of the +'80s, and he used to be in a rock group called the Quarrymen. If you have +trouble with some of the cultural references later in the book you'll have +to research them yourself.

»If you don't like my question, you could make up your own procedures +that ask different questions. Let's say you make up one called +sports.quiz and another called history.quiz, each asking and +answering one question. You could then put them all together into one +big quiz like this: + +

to total.quiz
+music.quiz
+sports.quiz
+history.quiz
+end
+

+ +

Saving Your Work

+ +

If you do write a collection of quiz procedures, you'll want to save +them so that they'll still be available the next time you use Logo. +Certainly you'll want to save the work you do in later chapters. +You can ask Logo to record all of the definitions you've made as +a workspace file using the save command. For example, +if you enter the instruction + +

save "mystuff
+

+ +

you are asking Logo to write a disk file called mystuff +containing everything you've defined. (The next time you use Logo, you can +get back your definitions with the load command.) + +

Don't get confused about the difference between a procedure name +and a workspace name. Logo beginners sometimes think that +save saves only a single procedure, the one whose name you tell it (in this +example, a procedure named mystuff). But the workspace file named +mystuff will actually contain all the procedures you've defined. +In fact, you probably don't have a procedure named mystuff. + +

The format for the name of a disk file will depend on the kind of computer +you're using, whether you're writing to a hard disk or a floppy disk, and so +on. Just use whatever file name format your system requires in other +programs, preceded by the quotation mark that tells Logo you're providing +a word as the input to the save command. + +

About Chapter 2

+ +

In this chapter the emphasis has been on doing things. You've +been playing around with some fairly intricate Logo instructions, +and if you don't understand everything about the examples, don't +let that worry you. + +

Chapter 2 has the opposite emphasis. There is very little to do, +and the examples will seem quite simple, perhaps even insultingly +simple! But the focus of the chapter is on understanding those +simple examples in great detail. + +

Logo deserves its reputation as an easy-to-learn language, but it +is also a very sophisticated one. The ease with which Logo can be +learned has lured many people into sloppy thinking habits that make +it hard for them to grow beyond the most trivial programming. By +studying examples that seem easy on the surface, we can start exploring +below the surface. The important questions will not be ones +like "what does print do," but instead ones like "what is going +on inside the Logo interpreter when I type print?" + +

Later chapters will strike more of a balance between things to do +and things to think about. If the pace seems slow in chapter 2, glance +back at the table of contents to reassure yourself about how much +territory we'll cover before the end of the book. Then keep in mind +that you'll need the ideas from chapter 2 in order to understand what +comes later. + +

No Exercises

+ +

This is the point in the chapter where you might be expecting a set +of exercises: Problem 1.1, get the computer to print your name. + +

There aren't any exercises--but not because you shouldn't try using +Logo at this point. The reason is that part of the challenge is for +you to invent things to try, not just rely on me for your ideas. +In each chapter there will be some sample procedures to illustrate +the new information in the chapter. You should try to invent programs +that use those ideas. + +

But I hope it's clear by now that I don't want you to do this with +a sense of duty. You should play with the ideas in each chapter only +to the extent that it's interesting and mind-stretching for you to +do so. + +

In this chapter I really haven't yet told you any of the rules for +putting together Logo instructions. (I'll do that in Chapter 2.) +So you shouldn't get discouraged or feel stupid if you don't get very +far, right now, in playing with Logo. It will be a few more chapters +before you should expect to feel really confident about undertaking +new projects of your own. But you won't break anything by trying +now. Go ahead, fool around! + +

(back to Table of Contents) +

BACK +chapter thread NEXT + +

+Brian Harvey, +bh@cs.berkeley.edu +

+ + diff --git a/js/games/nluqo.github.io/~bh/v1ch1/v1ch1.html b/js/games/nluqo.github.io/~bh/v1ch1/v1ch1.html new file mode 100644 index 0000000..8b5682b --- /dev/null +++ b/js/games/nluqo.github.io/~bh/v1ch1/v1ch1.html @@ -0,0 +1,449 @@ + + +Computer Science Logo Style vol 1 ch 1: Exploration + + +Computer Science Logo Style volume 1: +Symbolic Computing 2/e Copyright (C) 1997 MIT +