Problem Statement

Given a text file and an integer   n,   print/display the   n   most common words in the file   (and the number of their occurrences)   in decreasing frequency.

For the purposes of this task:

Show example output using Les Misérables from Project Gutenberg as the text file input and display the top   10   most used words.

This task was originally taken from programming pearls from Communications of the ACM June 1986 Volume 29 Number 6 where this problem is solved by Donald Knuth using literate programming and then critiqued by Doug McIlroy, demonstrating solving the problem in a 6 line Unix shell script (provided as an example below).

Let's start with the solution:

include ..\Utilitys.pmt

"loading..." ?
"135-0.txt" "r" fopen var fn
" "
true
while
    fn fgets number? if drop fn fclose false else lower " " chain chain true endif
endwhile

"process..." ?
len for
    var i
    i get dup 96 > swap 123 < and not if 32 i set endif
endfor
split sort

"count..." ?
( ) var words
"" var prev
1 var n
len for
    var i
    i get dup prev ==
    if
        drop n 1 + var n
    else
        words ( n prev ) 0 put var words var prev 1 var n
    endif
endfor
drop
words sort
10 for
    -1 * get ?
endfor
drop