<s>
Hume	B-Language
is	O
a	O
functionally	O
based	O
programming	O
language	O
developed	O
at	O
the	O
University	O
of	O
St	O
Andrews	O
and	O
Heriot-Watt	O
University	O
in	O
Scotland	O
since	O
the	O
year	O
2000	O
.	O
</s>
<s>
The	O
language	O
name	O
is	O
both	O
an	O
acronym	O
meaning	O
'	O
Higher-order	O
Unified	O
Meta-Environment	O
'	O
and	O
an	O
honorific	O
to	O
the	O
18th-century	O
philosopher	O
David	O
Hume	B-Language
.	O
</s>
<s>
It	O
targets	O
real-time	B-General_Concept
embedded	B-Architecture
systems	I-Architecture
,	O
aiming	O
to	O
produce	O
a	O
design	O
that	O
is	O
both	O
highly	O
abstract	O
,	O
yet	O
which	O
will	O
still	O
allow	O
precise	O
extraction	O
of	O
time	O
and	O
space	O
execution	O
costs	O
.	O
</s>
<s>
Hume	B-Language
combines	O
functional	B-Language
programming	I-Language
ideas	O
with	O
ideas	O
from	O
finite	B-Architecture
state	I-Architecture
automata	I-Architecture
.	O
</s>
<s>
Automata	O
are	O
used	O
to	O
structure	O
communicating	O
programs	O
into	O
a	O
series	O
of	O
"	O
boxes	O
"	O
,	O
where	O
each	O
box	O
maps	O
inputs	O
to	O
outputs	O
in	O
a	O
purely	B-Application
functional	I-Application
way	O
using	O
high-level	O
pattern-matching	O
.	O
</s>
<s>
The	O
Hume	B-Language
language	O
design	O
attempts	O
to	O
maintain	O
the	O
essential	O
properties	O
and	O
features	O
required	O
by	O
the	O
embedded	B-Architecture
systems	I-Architecture
domain	O
(	O
especially	O
for	O
transparent	O
time	O
and	O
space	O
costing	O
)	O
whilst	O
incorporating	O
as	O
high	O
a	O
level	O
of	O
program	O
abstraction	O
as	O
possible	O
.	O
</s>
<s>
It	O
aims	O
to	O
target	O
applications	O
ranging	O
from	O
simple	O
micro-controllers	O
to	O
complex	O
real-time	B-General_Concept
systems	I-General_Concept
such	O
as	O
smartphones	B-Application
.	O
</s>
<s>
The	O
inner	O
layer	O
is	O
stateless	O
and	O
purely	B-Application
functional	I-Application
.	O
</s>
<s>
RTSJ	B-Language
)	O
,	O
the	O
approach	O
taken	O
by	O
the	O
Hume	B-Language
designers	O
is	O
to	O
design	O
Hume	B-Language
in	O
such	O
a	O
way	O
that	O
formal	O
models	O
and	O
proofs	O
can	O
definitely	O
be	O
constructed	O
.	O
</s>
<s>
Hume	B-Language
is	O
structured	O
as	O
a	O
series	O
of	O
overlapping	O
language	O
levels	O
,	O
where	O
each	O
level	O
adds	O
expressibility	O
to	O
the	O
expression	O
semantics	O
,	O
but	O
either	O
loses	O
some	O
desirable	O
property	O
or	O
increases	O
the	O
technical	O
difficulty	O
of	O
providing	O
formal	O
correctness/cost	O
models	O
.	O
</s>
<s>
The	O
coordination	O
system	O
wires	O
boxes	O
in	O
a	O
dataflow	B-Application
programming	I-Application
style	O
.	O
</s>
<s>
The	O
expression	O
language	O
is	O
Haskell-like	O
.	O
</s>
<s>
The	O
message	O
passing	O
concurrency	O
system	O
remembers	O
JoCaml	B-Language
's	O
Join	B-Operating_System
patterns	I-Operating_System
or	O
Polyphonic	B-Language
C	I-Language
Sharp	I-Language
chords	B-Operating_System
,	O
but	O
with	O
all	O
channels	O
asynchronous	O
.	O
</s>
