<s>
FP	B-Language
(	O
short	O
for	O
functional	O
programming	O
)	O
is	O
a	B-Language
programming	I-Language
language	I-Language
created	O
by	O
John	O
Backus	O
to	O
support	O
the	O
function-level	B-Application
programming	I-Application
paradigm	O
.	O
</s>
<s>
It	O
allows	O
building	O
programs	O
from	O
a	O
set	O
of	O
generally	O
useful	O
primitives	O
and	O
avoiding	O
named	O
variables	O
(	O
a	O
style	O
also	O
called	O
tacit	B-Application
programming	I-Application
or	O
"	O
point	O
free	O
"	O
)	O
.	O
</s>
<s>
It	O
was	O
heavily	O
influenced	O
by	O
APL	B-Language
which	O
was	O
developed	O
by	O
Kenneth	O
E	O
.	O
Iverson	O
in	O
the	O
early	O
1960s	O
.	O
</s>
<s>
The	O
FP	B-Language
language	O
was	O
introduced	O
in	O
Backus	O
's	O
1977	O
Turing	O
Award	O
paper	O
,	O
"	O
Can	O
Programming	O
Be	O
Liberated	O
from	O
the	O
von	O
Neumann	O
Style	O
?	O
</s>
<s>
The	O
paper	O
sparked	O
interest	O
in	O
functional	O
programming	O
research	O
,	O
eventually	O
leading	O
to	O
modern	O
functional	O
languages	O
,	O
which	O
are	O
largely	O
founded	O
on	O
the	O
lambda	B-Language
calculus	I-Language
paradigm	O
,	O
and	O
not	O
the	O
function-level	B-Application
paradigm	O
Backus	O
had	O
hoped	O
.	O
</s>
<s>
In	O
his	O
Turing	O
award	O
paper	O
,	O
Backus	O
described	O
how	O
the	O
FP	B-Language
style	O
is	O
different	O
:	O
</s>
<s>
FP	B-Language
itself	O
never	O
found	O
much	O
use	O
outside	O
of	O
academia	O
.	O
</s>
<s>
In	O
the	O
1980s	O
Backus	O
created	O
a	O
successor	O
language	O
,	O
FL	B-Language
,	O
which	O
was	O
an	O
internal	O
project	O
at	O
IBM	O
Research	O
.	O
</s>
<s>
The	O
values	O
that	O
FP	B-Language
programs	O
map	O
into	O
one	O
another	O
comprise	O
a	O
set	O
which	O
is	O
closed	O
under	O
sequence	O
formation	O
:	O
</s>
<s>
FP	B-Language
programs	O
are	O
functions	O
f	O
that	O
each	O
map	O
a	O
single	O
value	O
x	O
into	O
another	O
:	O
</s>
<s>
Functions	O
are	O
either	O
primitive	O
(	O
i.e.	O
,	O
provided	O
with	O
the	O
FP	B-Language
environment	O
)	O
or	O
are	O
built	O
from	O
the	O
primitives	O
by	O
program-forming	O
operations	O
(	O
also	O
called	O
functionals	O
)	O
.	O
</s>
<s>
These	O
are	O
the	O
core	O
functionals	O
of	O
FP	B-Language
:	O
</s>
<s>
FP84	B-Language
is	O
an	O
extension	O
of	O
FP	B-Language
to	O
include	O
infinite	O
sequences	O
,	O
programmer-defined	O
combining	O
forms	O
(	O
analogous	O
to	O
those	O
that	O
Backus	O
himself	O
added	O
to	O
FL	B-Language
,	O
his	O
successor	O
to	O
FP	B-Language
)	O
,	O
and	O
lazy	O
evaluation	O
.	O
</s>
<s>
Unlike	O
FFP	B-Language
,	O
another	O
one	O
of	O
Backus	O
 '	O
own	O
variations	O
on	O
FP	B-Language
,	O
FP84	B-Language
makes	O
a	O
clear	O
distinction	O
between	O
objects	O
and	O
functions	O
:	O
i.e.	O
,	O
the	O
latter	O
are	O
no	O
longer	O
represented	O
by	O
sequences	O
of	O
the	O
former	O
.	O
</s>
<s>
FP84	B-Language
's	O
extensions	O
are	O
accomplished	O
by	O
removing	O
the	O
FP	B-Language
restriction	O
that	O
sequence	O
construction	O
be	O
applied	O
only	O
to	O
non-	O
⊥	O
objects	O
:	O
in	O
FP84	B-Language
the	O
entire	O
universe	O
of	O
expressions	O
(	O
including	O
those	O
whose	O
meaning	O
is	O
⊥	O
)	O
is	O
closed	O
under	O
sequence	O
construction	O
.	O
</s>
<s>
FP84	B-Language
's	O
semantics	O
are	O
embodied	O
in	O
an	O
underlying	O
algebra	O
of	O
programs	O
,	O
a	O
set	O
of	O
function-level	B-Application
equalities	O
that	O
may	O
be	O
used	O
to	O
manipulate	O
and	O
reason	O
about	O
programs	O
.	O
</s>
