<s>
Crystal	O
is	O
a	O
high-level	B-Language
general-purpose	B-Language
,	O
object-oriented	B-Language
programming	I-Language
language	I-Language
,	O
designed	O
and	O
developed	O
by	O
Ary	O
Borenszweig	O
,	O
Juan	O
Wajnerman	O
,	O
Brian	O
Cardiff	O
and	O
more	O
than	O
400	O
contributors	O
.	O
</s>
<s>
With	O
syntax	O
inspired	O
by	O
the	O
language	O
Ruby	B-Language
,	O
it	O
is	O
a	O
compiled	B-Language
language	I-Language
with	O
static	O
type-checking	O
,	O
but	O
specifying	O
the	O
types	O
of	O
variables	O
or	O
method	O
arguments	O
is	O
generally	O
unneeded	O
.	O
</s>
<s>
It	O
is	O
released	O
as	O
free	B-License
and	I-License
open-source	I-License
software	I-License
under	O
the	O
Apache	B-Application
License	I-Application
version	O
2.0	O
.	O
</s>
<s>
Work	O
on	O
the	O
language	O
began	O
in	O
June	O
2011	O
,	O
with	O
the	O
aim	O
of	O
merging	O
the	O
elegance	O
and	O
productivity	O
of	O
Ruby	B-Language
with	O
the	O
speed	O
,	O
efficiency	O
,	O
and	O
type	O
safety	O
of	O
a	O
compiled	B-Language
language	I-Language
.	O
</s>
<s>
The	O
Crystal	O
compiler	O
was	O
first	O
written	O
in	O
Ruby	B-Language
,	O
but	O
later	O
rewritten	O
in	O
Crystal	O
,	O
thus	O
becoming	O
self-hosting	O
,	O
as	O
of	O
November	O
2013	O
.	O
</s>
<s>
Although	O
resembling	O
the	O
Ruby	B-Language
language	I-Language
in	O
syntax	O
,	O
Crystal	O
compiles	O
to	O
much	O
more	O
efficient	O
native	O
code	O
using	O
an	O
LLVM	B-Application
backend	O
,	O
at	O
the	O
cost	O
of	O
precluding	O
the	O
dynamic	O
aspects	O
of	O
Ruby	B-Language
.	O
</s>
<s>
It	O
has	O
automated	O
garbage	O
collection	O
and	O
offers	O
a	O
Boehm	B-Language
collector	I-Language
.	O
</s>
<s>
Its	O
concurrency	B-Architecture
model	O
is	O
inspired	O
by	O
communicating	O
sequential	O
processes	O
(	O
CSP	O
)	O
and	O
implements	O
lightweight	O
fibers	O
and	O
channels	O
(	O
for	O
interfiber	O
communication	O
)	O
inspired	O
by	O
Go	B-Application
.	O
</s>
<s>
The	O
same	O
as	O
in	O
Ruby	B-Language
.	O
</s>
<s>
Or	O
using	O
an	O
object-oriented	B-Language
programming	I-Language
style	O
:	O
</s>
