<s>
A	O
higher	B-Application
order	I-Application
message	I-Application
(	O
HOM	O
)	O
in	O
a	O
computer	O
programming	O
language	O
is	O
a	O
form	O
of	O
higher-order	B-Application
programming	I-Application
that	O
allows	O
messages	O
that	O
have	O
other	O
messages	O
as	O
arguments	O
.	O
</s>
<s>
The	O
concept	O
was	O
introduced	O
at	O
MacHack	B-Application
2003	O
by	O
Marcel	O
Weiher	O
and	O
presented	O
in	O
a	O
more	O
complete	O
form	O
in	O
2005	O
by	O
Marcel	O
Weiher	O
and	O
Stéphane	O
Ducasse	O
.	O
</s>
<s>
Loops	O
can	O
be	O
written	O
without	O
naming	O
the	O
collections	O
looped	O
over	O
,	O
higher	B-Application
order	I-Application
messages	I-Application
can	O
be	O
viewed	O
as	O
a	O
form	O
of	O
point-free	O
or	O
tacit	B-Application
programming	I-Application
.	O
</s>
<s>
In	O
ordinary	O
Smalltalk	B-Application
code	O
,	O
without	O
using	O
HOM	O
,	O
obtaining	O
a	O
collection	O
of	O
the	O
employees	O
that	O
have	O
a	O
salary	O
of	O
1000	O
would	O
be	O
achieved	O
with	O
the	O
following	O
code	O
:	O
</s>
<s>
Here	O
,	O
select	O
is	O
a	O
higher	B-Application
order	I-Application
message	I-Application
,	O
and	O
hasSalary	O
:	O
is	O
understood	O
to	O
be	O
called	O
on	O
the	O
select	O
message	O
itself	O
,	O
rather	O
than	O
on	O
its	O
result	O
.	O
</s>
<s>
The	O
Smalltalk	B-Application
language	O
was	O
not	O
modified	O
to	O
implement	O
this	O
feature	O
.	O
</s>
<s>
Another	O
example	O
is	O
the	O
use	O
of	O
future	O
message	O
sends	O
in	O
the	O
Croquet	B-Protocol
Project	I-Protocol
:	O
</s>
<s>
The	O
reference	O
implementation	O
in	O
Objective-C	B-Language
leverages	O
the	O
trait	O
that	O
in	O
Objective-C	B-Language
,	O
objects	O
that	O
do	O
n't	O
understand	O
a	O
message	O
sent	O
to	O
them	O
,	O
still	O
get	O
it	O
delivered	O
in	O
a	O
special	O
hook	O
method	O
,	O
called	O
forward	O
:	O
.	O
</s>
<s>
Higher	O
order	O
messaging	O
was	O
implemented	O
in	O
a	O
number	O
of	O
languages	O
that	O
share	O
this	O
feature	O
including	O
Ruby	B-Language
and	O
Smalltalk	B-Application
.	O
</s>
<s>
ECMAScript	O
Harmony	O
's	O
Proxies	O
documentation	O
specifically	O
mentions	O
higher	B-Application
order	I-Application
messages	I-Application
as	O
an	O
application	O
for	O
their	O
Catchall	O
Proxies	O
.	O
</s>
<s>
The	O
programming	O
language	O
J	B-Language
distinguishes	O
between	O
verbs	O
and	O
adverbs	O
.	O
</s>
<s>
This	O
is	O
similar	O
to	O
higher	B-Application
order	I-Application
messages	I-Application
(	O
the	O
adverbs	O
)	O
modifying	O
the	O
messages	O
that	O
follow	O
(	O
the	O
verbs	O
)	O
.	O
</s>
