<s>
Time	B-Application
travel	I-Application
debugging	I-Application
or	O
time	O
traveling	O
debugging	O
is	O
the	O
process	O
of	O
stepping	O
back	O
in	O
time	O
through	O
source	O
code	O
to	O
understand	O
what	O
is	O
happening	O
during	O
execution	B-General_Concept
of	O
a	O
computer	B-Application
program	I-Application
.	O
</s>
<s>
Typically	O
,	O
debugging	O
and	O
debuggers	B-Application
,	O
tools	O
that	O
assist	O
a	O
user	O
with	O
the	O
process	O
of	O
debugging	O
,	O
allow	O
users	O
to	O
pause	O
the	O
execution	B-General_Concept
of	O
running	O
software	O
and	O
inspect	O
the	O
current	O
state	O
of	O
the	O
program	O
.	O
</s>
<s>
Interactive	O
debuggers	B-Application
include	O
the	O
ability	O
to	O
modify	O
code	O
and	O
step	O
forward	O
based	O
on	O
updated	O
information	O
.	O
</s>
<s>
Reverse	O
debugging	B-Application
tools	I-Application
allow	O
users	O
to	O
step	O
backwards	O
in	O
time	O
through	O
the	O
steps	O
that	O
resulted	O
in	O
reaching	O
a	O
particular	O
point	O
in	O
the	O
program	O
.	O
</s>
<s>
Time	O
traveling	O
debuggers	B-Application
provide	O
these	O
features	O
and	O
also	O
allow	O
users	O
to	O
interact	O
with	O
the	O
program	O
,	O
changing	O
the	O
history	O
if	O
desired	O
,	O
and	O
watch	O
how	O
the	O
program	O
responds	O
.	O
</s>
<s>
Selecting	O
a	O
purely	B-Application
functional	I-Application
programming	I-Application
language	O
helps	O
due	O
to	O
the	O
self-contained	O
nature	O
of	O
pure	B-Application
functions	I-Application
.	O
</s>
<s>
Pure	B-Application
functions	I-Application
have	O
no	O
side	O
effects	O
and	O
depend	O
only	O
on	O
the	O
information	O
explicitly	O
provided	O
to	O
the	O
function	O
,	O
providing	O
a	O
repeatable	O
,	O
reliable	O
,	O
replayable	O
path	O
through	O
the	O
code	O
.	O
</s>
<s>
Languages	O
and	O
debuggers	B-Application
that	O
enable	O
hot	B-Device
swapping	I-Device
,	O
the	O
ability	O
to	O
modify	O
code	O
as	O
the	O
code	O
is	O
running	O
,	O
provide	O
some	O
of	O
the	O
requirements	O
necessary	O
to	O
rewind	O
,	O
and	O
potentially	O
rewrite	O
execution	B-General_Concept
.	O
</s>
<s>
Tools	O
based	O
on	O
the	O
GNU	B-Language
debugger	I-Language
(	O
GDB	B-Language
)	O
,	O
available	O
for	O
compatible	O
languages	O
such	O
as	O
C	B-Language
,	O
C++	B-Language
,	O
Go	B-Application
,	O
and	O
Fortran	B-Application
are	O
capable	O
of	O
reverse	O
debugging	O
,	O
but	O
the	O
effort	O
significantly	O
slows	O
interaction	O
.	O
</s>
<s>
Examples	O
of	O
Debuggers	B-Application
with	O
the	O
ability	O
to	O
step	O
backwards	O
:	O
</s>
