<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
metalinguistic	B-Application
abstraction	I-Application
is	O
the	O
process	O
of	O
solving	O
complex	O
problems	O
by	O
creating	O
a	O
new	O
language	O
or	O
vocabulary	O
to	O
better	O
understand	O
the	O
problem	O
space	O
.	O
</s>
<s>
It	O
is	O
a	O
recurring	O
theme	O
in	O
the	O
seminal	O
MIT	O
textbook	O
Structure	B-Language
and	I-Language
Interpretation	I-Language
of	I-Language
Computer	I-Language
Programs	I-Language
,	O
which	O
uses	O
Scheme	B-Language
,	O
a	O
dialect	O
of	O
Lisp	B-Language
,	O
as	O
a	O
framework	O
for	O
constructing	O
new	O
languages	O
.	O
</s>
<s>
A	O
procedural	B-Application
(	O
e.g.	O
</s>
<s>
C	B-Language
)	O
programmer	O
might	O
create	O
data	O
structures	O
to	O
represent	O
these	O
elements	O
of	O
an	O
airport	O
and	O
procedures	O
or	O
routines	O
to	O
operate	O
on	O
those	O
data	O
structures	O
and	O
update	O
them	O
,	O
modelling	O
the	O
airport	O
as	O
a	O
series	O
of	O
processes	O
undergone	O
by	O
its	O
various	O
elements	O
.	O
</s>
<s>
An	O
object-oriented	B-Language
(	O
e.g.	O
</s>
<s>
Java	B-Language
)	O
programmer	O
might	O
create	O
objects	O
to	O
represent	O
the	O
elements	O
of	O
the	O
airport	O
with	O
methods	O
which	O
represent	O
their	O
behaviors	O
,	O
modelling	O
the	O
airport	O
as	O
a	O
collection	O
of	O
possibly	O
related	O
things	O
which	O
characteristically	O
interact	O
with	O
each	O
other	O
.	O
</s>
<s>
A	O
functional	B-Language
(	O
e.g.	O
</s>
<s>
Scheme	B-Language
)	O
programmer	O
might	O
create	O
higher-order	B-Language
functions	I-Language
representing	O
both	O
the	O
elements	O
and	O
behaviors	O
or	O
processes	O
of	O
the	O
airport	O
,	O
modelling	O
the	O
airport	O
as	O
a	O
map	O
of	O
relations	O
between	O
elements	O
in	O
its	O
various	O
domains	O
and	O
those	O
in	O
their	O
assorted	O
codomains	O
.	O
</s>
<s>
Finally	O
,	O
a	O
metalinguistic	O
programmer	O
might	O
abstract	O
the	O
problem	O
by	O
creating	O
new	O
domain-specific	B-Language
languages	I-Language
for	O
modelling	O
airports	O
,	O
with	O
peculiar	O
primitives	O
and	O
types	O
for	O
doing	O
so	O
.	O
</s>
<s>
The	O
new	O
language	O
could	O
encompass	O
any	O
or	O
all	O
of	O
the	O
above	O
approaches	O
where	O
most	O
suitable	O
,	O
potentially	O
enabling	O
the	O
programmer	O
to	O
retain	O
both	O
the	O
abstract	O
generality	O
of	O
the	O
functional	B-Language
model	O
,	O
the	O
intuitive	O
sensibility	O
of	O
the	O
object	O
model	O
,	O
and	O
the	O
detail-driven	O
pragmatism	O
of	O
the	O
procedural	B-Application
model	O
.	O
</s>
<s>
Because	O
the	O
creation	O
of	O
functional	B-Language
metalinguistic	B-Application
abstractions	I-Application
in	O
non-functional	B-Application
languages	O
can	O
be	O
cumbersome	O
while	O
the	O
reverse	O
is	O
usually	O
trivial	O
(	O
e.g.	O
</s>
<s>
it	O
is	O
generally	O
much	O
easier	O
to	O
take	O
a	O
side-effect-free	O
programming	O
abstraction	O
and	O
simply	O
add	O
effects	O
to	O
it	O
than	O
it	O
is	O
to	O
take	O
a	O
stateful	O
abstraction	O
and	O
work	O
around	O
or	O
encapsulate	O
its	O
propagation	O
of	O
state	O
)	O
,	O
and	O
because	O
of	O
the	O
syntactic	O
flexibility	O
and	O
referential	O
safety	O
of	O
functional	B-Language
macros	O
,	O
metalinguistic	O
programming	O
is	O
mostly	O
idiomatic	O
of	O
functional	B-Language
programming	I-Language
languages	I-Language
.	O
</s>
