I have made an effort to get the interpreter working in as many Scheme
implementations as I could. Below is a list of supported and not
supported Schemes. "Supported" means I ran the example code pieces
(in prolog-examples.scm) and they worked as sxpected. I did no
further tests.

There are two ways to use PLL:

(load "pll-standalone.scm")    ;; this works on all supported schemes.

(import (pll))                 ;; only on the systems marked as having 
                               ;; support for R7RS modules



Scheme     version      R7RS module        Note
-----------------------------------------------
Chicken     4.*		Y
Gauche      0.9.4	Y
Guile       2.*		-
Chibi       0.7.2	Y
Husk        3.19.1	-
SISC        1.16.6	-
Saggitarius 0.7.1	Y
Gambit      4.7     	-                  Needs -:s flag for syntax rules, and SRFI-1
MIT Scheme  9.1.1       -
STklos      1.10	-

Currently not supported:

SigScheme  (syntax-rules is disabled in sigscheme for now)
TinyScheme (syntax-rules not implemented)
Scheme9    (very strange behavior -- needs investigation)
Kawa       (AMB doesn't work because of some different call/cc behavior)
Foment     (the Hanoi towers example eats up 100% CPU and never finishes)
SCM        (no support for cond-expand, but would probably work)
SIOD       (syntax-rules not implemented)