<s>
GNU	O
Ubiquitous	O
Intelligent	O
Language	O
for	O
Extensions	O
(	O
GNU	B-Application
Guile	I-Application
)	O
is	O
the	O
preferred	O
extension	B-Language
language	I-Language
system	O
for	O
the	B-Application
GNU	I-Application
Project	I-Application
and	O
features	O
an	O
implementation	O
of	O
the	O
programming	O
language	O
Scheme	B-Language
.	O
</s>
<s>
In	O
addition	O
to	O
large	O
parts	O
of	O
Scheme	B-Language
standards	O
,	O
Guile	B-Application
Scheme	I-Application
includes	O
modularized	O
extensions	O
for	O
many	O
different	O
programming	O
tasks	O
.	O
</s>
<s>
For	O
extending	O
programs	O
,	O
Guile	O
offers	O
libguile	O
which	O
allows	O
the	O
language	O
to	O
be	O
embedded	O
in	O
other	O
programs	O
,	O
and	O
integrated	O
closely	O
through	O
the	O
C	B-Language
language	I-Language
application	B-Application
programming	I-Application
interface	I-Application
(	O
API	B-Application
)	O
;	O
similarly	O
,	O
new	O
data	O
types	O
and	O
subroutines	O
defined	O
through	O
the	O
C	B-Language
API	B-Application
can	O
be	O
made	O
available	O
as	O
extensions	O
to	O
Guile	O
.	O
</s>
<s>
Guile	O
is	O
used	O
in	O
programs	O
such	O
as	O
GnuCash	B-Language
,	O
LilyPond	B-Application
,	O
GNU	B-Language
Debugger	I-Language
,	O
GNU	B-Application
Guix	I-Application
,	O
GNU	O
Make	O
,	O
GNU	B-Application
TeXmacs	I-Application
and	O
.	O
</s>
<s>
Guile	B-Application
Scheme	I-Application
is	O
a	O
general-purpose	B-Language
,	O
high-level	B-Language
programming	I-Language
language	I-Language
whose	O
flexibility	O
allows	O
expressing	O
concepts	O
in	O
fewer	O
lines	O
of	O
code	O
than	O
would	O
be	O
possible	O
in	O
languages	O
such	O
as	O
C	B-Language
.	O
For	O
example	O
,	O
its	O
hygienic	O
macro	O
system	O
allows	O
adding	O
domain	O
specific	O
syntax-elements	O
without	O
modifying	O
Guile	O
.	O
</s>
<s>
Guile	O
implements	O
the	O
Scheme	B-Language
standard	O
R5RS	B-Language
,	O
most	O
of	O
R6RS	O
and	O
R7RS	O
,	O
several	O
Scheme	B-Language
Requests	I-Language
for	I-Language
Implementation	I-Language
(	O
SRFI	O
)	O
,	O
and	O
many	O
extensions	O
of	O
its	O
own	O
.	O
</s>
<s>
The	O
core	O
idea	O
of	O
Guile	B-Application
Scheme	I-Application
is	O
that	O
"	O
the	O
developer	O
implements	O
critical	O
algorithms	O
and	O
data	O
structures	O
in	O
C	B-Language
or	O
C++	O
and	O
exports	O
the	O
functions	O
and	O
types	O
for	O
use	O
by	O
interpreted	O
code	O
.	O
</s>
<s>
The	O
application	O
becomes	O
a	O
library	O
of	O
primitives	O
orchestrated	O
by	O
the	O
interpreter	O
,	O
combining	O
the	O
efficiency	O
of	O
compiled	B-Language
code	O
with	O
the	O
flexibility	O
of	O
interpretation.	O
"	O
</s>
<s>
Thus	O
Guile	B-Application
Scheme	I-Application
(	O
and	O
other	O
languages	O
implemented	O
by	O
Guile	O
)	O
can	O
be	O
extended	O
with	O
new	O
data	O
types	O
and	O
subroutines	O
implemented	O
through	O
the	O
C	B-Language
API	B-Application
.	O
</s>
<s>
The	O
standard	O
distribution	O
offers	O
modules	O
for	O
Portable	O
Operating	O
System	O
Interface	O
(	O
POSIX	O
)	O
system	O
calls	O
,	O
scheduling	O
,	O
a	O
foreign	B-Application
function	I-Application
interface	I-Application
,	O
S-expression	B-Protocol
based	O
XML	B-Protocol
processing	O
through	O
SXML	B-Language
,	O
SXPath	O
,	O
and	O
SXSLT	O
,	O
HTTP	B-Protocol
and	O
other	O
World	O
Wide	O
Web	O
APIs	B-Application
,	O
delimited	O
continuations	O
,	O
array	B-Application
programming	I-Application
,	O
and	O
other	O
functionality	O
.	O
</s>
<s>
Guile	O
programs	O
can	O
use	O
facilities	O
from	O
SLIB	B-Application
,	O
the	O
portable	O
Scheme	B-Language
library	O
.	O
</s>
<s>
When	O
using	O
continuations	O
with	O
call/cc	O
,	O
a	O
requirement	O
of	O
the	O
Scheme	B-Language
standard	O
,	O
Guile	O
copies	O
the	O
execution	O
stack	B-General_Concept
into	O
the	O
heap	B-General_Concept
and	O
back	O
.	O
</s>
<s>
Because	O
foreign	O
code	O
may	O
have	O
pointers	O
to	O
Scheme	B-Language
objects	O
,	O
Guile	O
uses	O
the	O
conservative	O
Boehm	B-Language
–	I-Language
Demers	I-Language
–	I-Language
Weiser	I-Language
(	O
BDW	O
)	O
garbage	B-General_Concept
collector	I-General_Concept
.	O
</s>
<s>
After	O
the	O
success	O
of	O
Emacs	B-Application
in	O
the	O
free	B-Application
software	I-Application
community	O
,	O
as	O
a	O
highly	O
extensible	O
and	O
customizable	O
application	O
via	O
its	O
extension	O
(	O
and	O
partly	O
implementation	O
)	O
language	O
Emacs	B-Operating_System
Lisp	I-Operating_System
,	O
the	O
community	O
began	O
to	O
consider	O
how	O
this	O
design	O
strategy	O
could	O
apply	O
to	O
the	O
rest	O
of	O
the	O
GNU	O
system	O
.	O
</s>
<s>
Tom	O
Lord	O
initially	O
began	O
work	O
on	O
an	O
embeddable	O
language	O
runtime	O
named	O
the	O
GNU	O
Extension	B-Language
Language	I-Language
(	O
GEL	O
)	O
,	O
which	O
was	O
based	O
on	O
Aubrey	O
Jaffer	O
's	O
Scheme	B-Language
implementation	O
SCM	B-Language
(	O
which	O
in	O
turn	O
was	O
based	O
on	O
George	O
Carrette	O
's	O
SIOD	B-Language
)	O
.	O
</s>
<s>
Lord	O
convinced	O
Richard	O
Stallman	O
to	O
make	O
GEL	O
the	O
official	O
extension	B-Language
language	I-Language
of	O
the	B-Application
GNU	I-Application
project	I-Application
,	O
based	O
on	O
the	O
argument	O
that	O
Scheme	B-Language
was	O
a	O
cleaner	O
Lisp	B-Language
dialect	O
than	O
Emacs	B-Operating_System
Lisp	I-Operating_System
,	O
and	O
that	O
GEL	O
could	O
evolve	O
to	O
implement	O
other	O
languages	O
on	O
the	O
same	O
runtime	O
,	O
namely	O
Emacs	B-Operating_System
Lisp	I-Operating_System
.	O
</s>
<s>
From	O
several	O
contributions	O
in	O
several	O
Usenet	B-Application
newsgroups	I-Application
,	O
Lord	O
controversially	O
chose	O
Guile	O
from	O
a	O
suggestion	O
by	O
Lee	O
Thomas	O
.	O
</s>
<s>
During	O
the	O
development	O
of	O
Guile	O
(	O
then	O
GEL	O
)	O
and	O
before	O
its	O
public	O
release	O
,	O
the	O
extension	B-Language
language	I-Language
Tcl	B-Operating_System
was	O
gaining	O
popularity	O
and	O
being	O
pushed	O
as	O
a	O
universal	O
extension	B-Language
language	I-Language
.	O
</s>
<s>
Stallman	O
saw	O
Tcl	B-Operating_System
as	O
being	O
underpowered	O
as	O
an	O
extension	B-Language
language	I-Language
,	O
and	O
posted	O
a	O
criticism	O
to	O
the	O
comp.lang.tcl	O
newsgroup	B-Application
,	O
which	O
initiated	O
a	O
flamewar	O
known	O
as	O
the	O
"	O
Tcl	B-Operating_System
War	O
"	O
.	O
</s>
<s>
Since	O
the	O
public	O
announcement	O
of	O
the	O
Guile	O
project	O
coincided	O
with	O
the	O
Tcl	B-Operating_System
debate	O
,	O
it	O
has	O
become	O
a	O
common	O
misconception	O
that	O
Guile	O
began	O
as	O
a	O
reaction	O
to	O
this	O
.	O
</s>
<s>
After	O
the	O
initial	O
release	O
of	O
Guile	O
,	O
development	O
languished	O
for	O
many	O
years	O
,	O
but	O
2009	O
–	O
2010	O
saw	O
major	O
improvements	O
,	O
and	O
Guile	O
2.0	O
was	O
released	O
in	O
2011	O
with	O
a	O
new	O
compiler	B-Language
infrastructure	O
,	O
a	O
virtual	B-Architecture
machine	I-Architecture
implementation	O
,	O
a	O
switch	O
to	O
the	O
Boehm	B-Language
–	I-Language
Demers	I-Language
–	I-Language
Weiser	I-Language
garbage	I-Language
collector	I-Language
,	O
many	O
improvements	O
to	O
the	O
Guile	B-Application
Scheme	I-Application
language	O
,	O
and	O
other	O
major	O
changes	O
.	O
</s>
<s>
One	O
of	O
the	O
goals	O
of	O
Guile	O
is	O
to	O
allow	O
other	O
languages	O
to	O
be	O
used	O
alongside	O
Scheme	B-Language
,	O
such	O
that	O
Guile	O
would	O
effectively	O
be	O
a	O
language-neutral	O
runtime	O
environment	O
.	O
</s>
<s>
Various	O
attempts	O
at	O
this	O
have	O
been	O
made	O
in	O
past	O
versions	O
:	O
a	O
dialect	O
of	O
Scheme	B-Language
essentially	O
differing	O
only	O
in	O
its	O
C-like	O
syntax	O
,	O
a	O
translation	O
of	O
Emacs	B-Operating_System
Lisp	I-Operating_System
,	O
a	O
Tcl	B-Operating_System
converter	O
motivated	O
by	O
tkWWW	B-Application
,	O
and	O
something	O
roughly	O
resembling	O
the	O
language	O
Logo	B-Device
.	O
</s>
<s>
With	O
version	O
2.0	O
,	O
the	O
project	O
successfully	O
transitioned	O
to	O
a	O
compiler	B-Language
tower	O
approach	O
,	O
allowing	O
the	O
definition	O
of	O
compilers	B-Language
from	O
one	O
language	O
to	O
another	O
,	O
typically	O
from	O
a	O
higher-level	O
one	O
to	O
a	O
lower-level	O
intermediate	B-Application
representation	I-Application
,	O
and	O
eventually	O
virtual	B-Architecture
machine	I-Architecture
bytecode	O
or	O
native	O
machine	B-Language
code	I-Language
.	O
</s>
<s>
On	O
16	O
Mar	O
2017	O
,	O
Guile	O
2.2.0	O
was	O
released	O
with	O
a	O
new	O
optimizing	O
compiler	B-Language
and	O
high-performance	O
register	O
virtual	B-Architecture
machine	I-Architecture
.	O
</s>
<s>
Guile	O
2.2.0	O
also	O
lowered	O
memory	B-General_Concept
usage	I-General_Concept
,	O
sped	O
up	O
the	O
"	O
eval	O
"	O
interpreter	O
,	O
provided	O
better	O
support	O
for	O
multi-core	O
programming	O
,	O
and	O
removed	O
any	O
fixed	O
limit	O
on	O
recursive	O
function	O
calls	O
.	O
</s>
<s>
It	O
also	O
supported	O
the	O
creation	O
of	O
user-space	O
concurrency	O
facilities	O
that	O
multiplex	O
millions	O
of	O
concurrent	O
lightweight	O
"	O
fibers	O
"	O
and	O
provided	O
a	O
complete	O
Emacs-compatible	O
Elisp	B-Operating_System
implementation	O
,	O
implementing	O
all	O
of	O
Elisp	B-Operating_System
's	O
features	O
and	O
quirks	O
in	O
the	O
same	O
way	O
as	O
Emacs	B-Application
.	O
</s>
<s>
On	O
16	O
January	O
2020	O
,	O
Guile	O
3.0.0	O
was	O
released	O
with	O
just-in-time	O
(	O
JIT	O
)	O
native	B-Language
code	I-Language
generation	O
for	O
much	O
greater	O
performance	O
.	O
</s>
<s>
It	O
also	O
featured	O
support	O
for	O
interleaved	O
definitions	O
and	O
expressions	O
in	O
lexical	O
contexts	O
,	O
native	O
support	O
for	O
structured	O
exceptions	O
,	O
better	O
support	O
for	O
the	O
R6RS	O
and	O
R7RS	O
Scheme	B-Language
standards	O
and	O
many	O
optimizations	O
.	O
</s>
<s>
There	O
have	O
been	O
several	O
past	O
unfinished	O
attempts	O
to	O
replace	O
or	O
supplement	O
Emacs	B-Application
's	O
Emacs	B-Operating_System
Lisp	I-Operating_System
(	O
Elisp	B-Operating_System
)	O
extension	B-Language
language	I-Language
with	O
Guile	O
,	O
parallel	O
to	O
the	O
efforts	O
of	O
supporting	O
other	O
languages	O
in	O
Guile	O
.	O
</s>
<s>
With	O
version	O
2.0	O
of	O
Guile	O
,	O
a	O
new	O
attempt	O
at	O
implementing	O
Elisp	B-Operating_System
on	O
the	O
Guile	O
compiler	B-Language
tower	O
and	O
replacing	O
Emacs	B-Application
's	O
Elisp	B-Operating_System
implementation	O
with	O
that	O
of	O
libguile	O
has	O
begun	O
and	O
made	O
significant	O
progress	O
through	O
Google	B-Application
Summer	I-Application
of	I-Application
Code	I-Application
projects	O
.	O
</s>
<s>
A	O
Guile-based	O
Emacs	B-Application
could	O
offer	O
better	O
execution	O
performance	O
for	O
Emacs	B-Operating_System
Lisp	I-Operating_System
,	O
support	O
new	O
Emacs	B-Operating_System
Lisp	I-Operating_System
language	O
features	O
more	O
easily	O
,	O
make	O
Guile	O
libraries	O
written	O
in	O
other	O
programming	O
languages	O
available	O
to	O
Emacs	B-Operating_System
Lisp	I-Operating_System
code	O
,	O
and	O
allow	O
writing	O
Emacs	B-Application
extensions	O
in	O
other	O
programming	O
languages	O
supported	O
by	O
Guile	O
,	O
all	O
while	O
remaining	O
fully	O
backward	O
compatible	O
with	O
existing	O
Emacs	B-Operating_System
Lisp	I-Operating_System
code	O
bases	O
.	O
</s>
<s>
,	O
the	O
implementation	O
had	O
reached	O
a	O
stage	O
where	O
Guile	O
Emacs	B-Application
is	O
able	O
to	O
reliably	O
run	O
most	O
Emacs	B-Operating_System
Lisp	I-Operating_System
code	O
.	O
</s>
<s>
Remaining	O
problems	O
or	O
possible	O
problems	O
involve	O
the	O
different	O
internal	O
representation	O
of	O
Emacs	B-Operating_System
Lisp	I-Operating_System
strings	O
from	O
Scheme	B-Language
strings	O
,	O
the	O
difference	O
between	O
how	O
Emacs	B-Operating_System
Lisp	I-Operating_System
and	O
Scheme	B-Language
treat	O
the	O
Boolean	O
false	O
and	O
empty	O
list	O
objects	O
,	O
Emacs	B-Operating_System
Lisp	I-Operating_System
macros	O
not	O
integrating	O
with	O
Scheme	B-Language
,	O
Emacs	B-Operating_System
Lisp	I-Operating_System
not	O
having	O
been	O
designed	O
for	O
concurrency	O
,	O
and	O
the	O
portability	O
of	O
Guile	O
to	O
platforms	O
supported	O
by	O
Emacs	B-Application
.	O
</s>
<s>
Other	O
concerns	O
raised	O
by	O
the	O
Emacs	B-Application
community	O
include	O
the	O
relative	O
sizes	O
of	O
the	O
Emacs	B-Application
and	O
Guile	O
communities	O
,	O
and	O
whether	O
it	O
would	O
cause	O
splitting	O
in	O
the	O
community	O
if	O
Emacs	B-Application
were	O
extensible	O
in	O
programming	O
languages	O
other	O
than	O
Emacs	B-Operating_System
Lisp	I-Operating_System
.	O
</s>
<s>
GNU	O
make	O
can	O
be	O
built	O
with	O
support	O
for	O
GNU	B-Application
Guile	I-Application
as	O
an	O
embedded	O
extension	B-Language
language	I-Language
.	O
</s>
