Hello, protist.

This is second time I saw the name 'High Order Perl'. It took me much time to remember the days with common lisp, but I tried anyway. I wonder what does mit classes uses for lisp? It seems different from common lisp...

Tested with clisp.

(defun sum_from_to(TERM from NEXT to)
    (IF (> from to)
        0
        (+ (funcall TERM from)
            (sum_from_to
                TERM
                (funcall NEXT from)
                NEXT
                to))))
        
(defun addone (c) (+ 1 c))
(defun self(x) x)
(defun square (A) (* A A))

(defun sum-int (A B)
    (sum_from_to #'self A #'addone B))

(defun sum-sq(A B)
    (sum_from_to #'square A #'addone B))

(print (sum-int 3 5))
(print (sum-sq 3 5))
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#!/usr/bin/perl
use strict; use warnings; use feature qw(say);
sub sum_from_to{
    my ($TERM, $from, $NEXT, $to)=@_; 
    if( $from > $to ){
        0; 
    } else {
        $TERM->($from)
        +   
        sum_from_to(
            $TERM,
            $NEXT->($from),
            $NEXT,
            $to
        );  
    }   
}
sub addone{ return 1 + $_[0]}
sub self{ return $_[0]}
sub square{ return $_[0] * $_[0]}

sub sum_int {
    my($A,$B)=@_;
    sum_from_to( \&self, $A, \&addone, $B);
}   
sub sum_sq {
    my($A,$B)=@_;
    sum_from_to( \&square, $A, \&addone, $B);
}  

say sum_int(3,5);
say sum_sq(3,5);
[download]