<s>
NPL	B-Language
is	O
a	O
functional	B-Language
programming	I-Language
language	I-Language
with	O
pattern	B-Language
matching	I-Language
designed	O
by	O
Rod	O
Burstall	O
and	O
John	O
Darlington	O
in	O
1977	O
.	O
</s>
<s>
The	O
NPL	B-Language
interpreter	O
evaluates	O
the	O
list	O
of	O
generators	O
from	O
left	O
to	O
right	O
so	O
conditions	O
can	O
mention	O
any	O
bound	O
variables	O
that	O
occur	O
to	O
their	O
left	O
.	O
</s>
<s>
These	O
were	O
known	O
as	O
set	B-Language
comprehensions	I-Language
.	O
</s>
<s>
NPL	B-Language
eventually	O
evolved	O
into	O
Hope	B-Language
but	O
lost	O
set	B-Language
comprehensions	I-Language
,	O
which	O
made	O
a	O
reappearance	O
in	O
the	O
form	O
of	O
list	B-Language
comprehensions	I-Language
in	O
later	O
functional	B-Language
languages	I-Language
.	O
</s>
