<s>
In	O
computer	B-General_Concept
science	I-General_Concept
,	O
strictness	B-Application
analysis	I-Application
refers	O
to	O
any	O
algorithm	O
used	O
to	O
prove	O
that	O
a	O
function	O
in	O
a	O
non-strict	B-Application
functional	B-Language
programming	I-Language
language	I-Language
is	O
strict	O
in	O
one	O
or	O
more	O
of	O
its	O
arguments	O
.	O
</s>
<s>
This	O
information	O
is	O
useful	O
to	O
compilers	B-Language
because	O
strict	O
functions	O
can	O
be	O
compiled	B-Language
more	O
efficiently	O
.	O
</s>
<s>
Thus	O
,	O
if	O
a	O
function	O
is	O
proven	O
to	O
be	O
strict	O
(	O
using	O
strictness	B-Application
analysis	I-Application
)	O
at	O
compile	B-Language
time	O
,	O
it	O
can	O
be	O
compiled	B-Language
to	O
use	O
a	O
more	O
efficient	O
calling	O
convention	O
without	O
changing	O
the	O
meaning	O
of	O
the	O
enclosing	O
program	O
.	O
</s>
<s>
The	O
notion	O
of	O
"	O
divergence	O
"	O
is	O
significant	O
because	O
a	O
strict	O
function	O
is	O
one	O
that	O
always	O
diverges	O
when	O
given	O
an	O
argument	O
that	O
diverges	O
,	O
whereas	O
a	O
lazy	O
(	O
or	O
non-strict	B-Application
)	O
function	O
is	O
one	O
that	O
may	O
or	O
may	O
not	O
diverge	O
when	O
given	O
such	O
an	O
argument	O
.	O
</s>
<s>
Strictness	B-Application
analysis	I-Application
attempts	O
to	O
determine	O
the	O
"	O
divergence	O
properties	O
"	O
of	O
functions	O
,	O
which	O
thus	O
identifies	O
some	O
functions	O
that	O
are	O
strict	O
.	O
</s>
<s>
Strictness	B-Application
analysis	I-Application
can	O
be	O
characterized	O
as	O
a	O
forward	O
abstract	O
interpretation	O
which	O
approximates	O
each	O
function	O
in	O
the	O
program	O
by	O
a	O
function	O
that	O
maps	O
divergence	O
properties	O
of	O
the	O
arguments	O
onto	O
divergence	O
properties	O
of	O
the	O
results	O
.	O
</s>
<s>
The	B-Application
Glasgow	I-Application
Haskell	I-Application
Compiler	I-Application
(	O
GHC	O
)	O
uses	O
a	O
backward	O
abstract	O
interpretation	O
known	O
as	O
demand	O
analysis	O
to	O
perform	O
strictness	B-Application
analysis	I-Application
as	O
well	O
as	O
other	O
program	O
analyses	O
.	O
</s>
<s>
Projection-based	O
strictness	B-Application
analysis	I-Application
,	O
introduced	O
by	O
Philip	O
Wadler	O
and	O
R.J.M.	O
</s>
<s>
There	O
was	O
a	O
large	O
body	O
of	O
research	O
on	O
strictness	B-Application
analysis	I-Application
in	O
the	O
1980s	O
.	O
</s>
