HYPERTEXT COMPUTER COMMANDS IN WORD PROCESSING

Arne Bergström

Scientor Research & Development
Essingekroken 9, S-112 65 Stockholm, Sweden
phone +46 8 695 0600 fax +46 8 695 0312
e-mail arne.bergstrom@scientor.se


    Historically, two different fields of use have converged into modern computer systems: the typewriter and the calculator. The capability of the computer to calculate and make logical choices are largely unexploited in today's wordprocessors.
    On the other hand Internet and web documents constitute an exciting, new development in publishing. Now for the first time, the long-advocated "paper-free world" seems imminent, since computer documents can indeed provide new capabilities with which printed paper cannot compete. Computer documents can be instantly available on Internet. Computer documents can be instantly updated and corrected. Computer documents can contain aminations and sound illustrations. Information on computer documents can be automatically indexed and searched.
    In addition - and this is the subject matter of this communication - computer documents have the potential of containing text and animations which are the result of calculations based on data taken, e g, from external sources and which may be used to automatically modify the text in the document as the result of such calculations.
    S_Polish is a testbed which illustrates the advantages of permitting calculations and logical choices hidden inside a text document, e g, to select output depending on the outcome of such calculations. A typical example would be an automatic economic report prepared in a wordprocessor, and which takes balance data from a file and chooses comments like "business is going fine" or "unless something is done, we will go bankrupt", depending on what is calculated from the input data.
    Another example of the use of S_Polish is the interactive mathematics programs produced by the Swedish company SciAce AB to teach children the multiplication tables (see poster "CAN YOUR CHILD THE MULTIPLICATION TABLES?" to the right) or to test their skill at elementary calculations. These programs are essentially prepared by a teacher on an ordinary word processor, and provide a complex web of questions, follow-up questions and pedagogical hints which depend on the pupil's answers.
    The important feature with S_Polish compared to existing computer programming is that the calculations are easily inserted as a kind of hypertext commands directly in the running text when typing the text in a word processor. As the name suggests, this is achieved by using operators in so-called Polish notation, by which even extremely complex programming structures can be formulated in linear form. By writing the programming commands in straight Polish notation it is possible to obtain a structure which closely resembles a natural language. Consider, for instance, a document in which the following actions are to be performed:

    Choose a random number between 1 and 100. Ask the reader to guess this number and type his guess on the keyboard. If his guess is right then display a message saying: "Bingo!"
    In S_Polish this could be performed in a running text by inserting a hypertext command as follows: ~{store_as right_guess random 1 100;write space Guess_a_number_between_1_and_100!;write Bingo! only if_equal right_guess input}.


    Most S_Polish operators are similar to customary computer commands. There are, however, some operators which are unique for S_Polish due to its special linear structure. One such example is the only command used above, by which the preceding part of a S_Polish sentence is ignored unless the Boolean expression in the operand is true. Also the S_Polish Boolean commands if_either and if_both are examples of special commands, specific to the linear structure inherent in word processing. Summaries of the S_Polish syntax and the most common operators are listed below.
    The present implementation of S_Polish also incorporates an intricate encryptation of the original text from the word processor which contains the S_Polish commands, making the text virtually impervious to pirate copying. All stored text and data are encrypted in a form which is specific for each computer or floppy disk with a license, and the text appears in decrypted, readable form only when displayed. It is not possible for the reader to infer, e g, which other alternatives are covered by the S_Polish commands besides those particular ones which are displayed in response to the input data in each specific case.

 

GENERAL PROPERTIES OF S_POLISH
     S_Polish commands can be inserted anywhere inside the running text. S_Polish commands are hypertext commands separated from the running, visible text by being enclosed within curly brackets and initiated by a tilde, i e like

running text ~{S_Polish command} running text ~{S_Polish command} running text
     Straight Polish notation is used, i e commands are typed after each other with operator first and then the corresponding operands upon which the operator works. The operands may in turn consist of operators and corresponding operands. Blanks are used as separators (underline _ is used to form multi-word operators and operands; use the space command to remove the underlines at output, if desired). The expressions are evaluated from right to left.
     Operators are predefined and have reserved names as listed below. Operands are separated by blanks and may be of the following types:

    i) numbers like 7, 78, or 3.1416

    ii) strings like elephant, or Kugeloberflächenfunktionen, of arbitrary length

    iii) variables with names which are strings. Strings as names of variables
    become defined by operators such as     store_as, save_as and the like.
    Unless so defined as variables, strings are displayed as they are spelled
    (this means that variables which have been left undefined by mistake will
    be displayed by their names, not by a default value)
     In order to simplify the expressions, it is permitted (and advised) to divide the S_Polish commands into sentences, separated by semicolons. With regard to the sentence structure, a S_Polish command is evaluated from left to right.



Type of operation Operator & operands

Example

 Result

Result of Example

 Comments
Input input

input

 get string from keyboard

what is typed on keyboard
and ended by Enter-key
Output write string

write sum 7 11

 string

18 is displayed on screen
Addition sum first_term second_term

sum 7 11

 first_term + second_term

18
Subtraction difference first_term second_term

difference 11 7

 first_term - second_term

4
Multiplication product first_factor second_factor

product 9 4

 first_factor * second_factor

36
Division quotient numerator denominator

quotient 36 4

 numerator/denominator

9
Clear clear variable

clear sum

 variable = 0

sum = 0
Increment increment variable

increment sum

 variable = variable + 1

sum = sum + 1
Decrement decrement variable

decrement sum

 variable = variable - 1

sum = sum - 1
Double double variable

double sum

 variable = variable * 2

sum = sum * 2
Triple triple variable

triple sum

 variable = variable * 3

sum = sum * 3
Half half variable

half sum

 variable = variable / 2

sum = sum / 2
Square square variable

square sum

 variable = variable2

sum = sum2
Cube cube variable

cube sum

 variable = variable3

sum = sum3
Form floating mean float_mean var1 var2

float_mean sum triple sum

 var1 = (var1 + var2)/2

sum = 2 * sum
Concatenation concat first_string second_string

concat Mr_Pre sident

 first_stringsecond_string

Mr_President
Spacing space string_with_underlines

space Franklin_Delano_Roosevelt

 string with spaces

Franklin Delano Roosevelt
Unspacing unspace string

unspace space F_D_R

 stringwithspacesdeleted

FDR
Upcasing upcase string

upcase fdr

 UPCASE_STRING

FDR
Downcasing downcase string

downcase FDR

 downcase_string

fdr
Namestyling namestyle string

namestyle mr a von capone y d'nice

 String With Initial Capitals

Mr A von Capone y d'Nice

 von, van, d', y, af
etc are displayed
in downcase form
Timestyling timestyle integer.decimal

timestyle 3.10

 leading zeroes inserted

03.10
Get time time

time

 current time

03.06
Add times addclock time1 time2

addclock 19.50 05.15

 time1 + time2

01.05
Extract numerical part numpart string

numpart pi=3.1416

 numerical_substring

3.1416
Extract textpart textpart string

textpart pi=3.1416

 text_substring

pi=
Extract integer part intpart string

intpart pi=3.1416

 integer__part_of _string

3
Find greatest operand greatest_of 1st_number 2nd_number

greatest_of 6 5.98

 max(1st number,2nd number)

6
Find smallest operand least_of 1st_number 2nd_number

least_of 6 5.98

 min(1st number,2nd number)

5.98
Choose random number random lo_limit hi_limit

random 2.6 9

 lo_limit<random number<hi_limit

5.3

 rectangular
distribution
Select random item random_of op1 op2 ... opn end

random_of mg cg gram kg end

 one operator chosen at random

gram

 error message
if end missing
Select item in list select index op1 op2 ... opn end

select 3 mg cg gram kg end

 op(index)

gram

 error message
if end missing
Test if equal if_equal operand1 operand2

if_equal A B

 true if operand1=operand2

true if A=B
Test if different if_different operand1 operand2

if_different A B

 true if not operand1=operand2

true if not A=B
Test if greater if_greater operand1 operand2

if_greater A B

 true if operand1>operand2

true if A>B
Test if less if_less operand1 operand2

if_less A B

 true if operand1<operand2

true if A<B
Test if both true if_both operand1 operand2

if_both if_equal A B if_less A 7

 true if both operands are true

true if both A=B and A<7
Test if either true if_either operand1 operand2

if_either if_equal A B if_less A 7

 true if either operand is true

true if either A=B or A<7
Test for substring if_in string substring

if_in Napoleon leo

 true if substring in string

true
Test for previous
address before jump		 if_from address

if_from #5

 true if address before jump

true if #5 previous address
Do only if true only Boolean expression

write YES only if_equal 3 sum 2 1

 continue only if true

YES is displayed on screen
Conditional jump branch_to address Boolean expression

branch_to adr1 if_equal A 3

 jump to address if true

jump to adr1 if A=3

 address may be
an anchor in a
HTML document
Unconditional jump go_to address

go_to adr1

 jump to address

jump to adr1

 address may be
an anchor in a
HTML document
Store as temporary variable store_as variable_name value

store_as pi 3.1416

 variable_name = value

pi=3.1416
Save as permanent variable save_as variable_name value

save_as pi 3.1416

 variable_name = value (saved)

pi=3.1416 on hard disk