The SNOBOL Programming Language

Description

Hark! hark! the lark at heaven's gate sings,
And Phoebus 'gins arise,
His steeds to water at those springs
On chaliced flowers that lies;
And winking Mary-buds begin
To ope their golden eyes;
With every thing that pretty is,
My lady sweet arise:
Arise, arise!

Source Code

*	WORDSIZE.SNO
*
*	Program to read a file and display the number of words of
*	various word lengths.  To make the program more interesting,
*	we shall only consider word lengths between 3 and 9.  This allows
*	us to demonstrate the use of an array with subscripts offset from
*	1, as well as array failure.
*
*	The file being scanned is read from standard input.  For example,
*	to scan the file TEXT.IN, type:
*
*		SNOBOL4 WORDSIZE <TEXT.IN
*
*	Trim trailing blanks from input
*
	&TRIM	=	1

*	Define pattern for words.  A word consists of upper- and lower-case
*	letters, apostrosphe and hyphen.
*
	WORDPAT	=	BREAK(&LCASE &UCASE) SPAN(&LCASE &UCASE "'-") . WORD

*	Define the array to hold the word counts.  Valid subscripts must be
*	in the range 3 through 9; all others will cause the array reference
*	to fail.  Array elements are initialized to zero instead of the normal
*	default, which is the null string.  This causes a zero to be produced
*	in the printed output if a particular array entry is never incremented.
*
	COUNT	=	ARRAY('3:9',0)

*	Read a line from the input file.  Fail if end-of-file.
*
READ	LINE	=	INPUT				:F(DONE)

*	Find the next word in LINE, and remove it to WORD.  Fail when
*	no more words remain in the line.
*
NEXTW	LINE WORDPAT =					:F(READ)

*	Increment the appropriate array element for words of this
*	size.  The statement quietly fails if the size is outside
*	the range 3 through 9.
*
	COUNT<SIZE(WORD)> = COUNT<SIZE(WORD)>+ 1	:(NEXTW)

*	Upon end of file, print the values in the array.  Print heading first.
*
DONE	OUTPUT	=	"WORD LENGTH     NUMBER OF OCCURRENCES"
	I	=	2

*	Index through array starting at element 3.  When we reach element
*	10, the array reference fails, and we fall through to END.
*
PRINT	I	=	I + 1
	OUTPUT	=	LPAD(I,5) LPAD(COUNT<I>,20)	:S(PRINT)

END

Sample Run

Word Length             Number of Occurrencess
         3                           5
         4                           11
         5                           12
         6                           3
         7                           4
         8                           2
         9                           1

Program Notes