<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
Programming	B-Language
Computable	I-Language
Functions	I-Language
(	O
PCF	O
)	O
is	O
a	O
typed	O
functional	B-Language
language	I-Language
introduced	O
by	O
Gordon	O
Plotkin	O
in	O
1977	O
,	O
based	O
on	O
previous	O
unpublished	O
material	O
by	O
Dana	O
Scott	O
.	O
</s>
<s>
It	O
can	O
be	O
considered	O
to	O
be	O
an	O
extended	O
version	O
of	O
the	O
typed	O
lambda	B-Language
calculus	I-Language
or	O
a	O
simplified	O
version	O
of	O
modern	O
typed	O
functional	B-Language
languages	I-Language
such	O
as	O
ML	B-Language
or	O
Haskell	B-Language
.	O
</s>
