ATS Programming Tutorial

ATS Programming TutorialATS Programming TutorialATS Programming TutorialATS Programming TutorialATS Programming Tutorial
Kiwamu Okabe @ RIKEN AICSKiwamu Okabe @ RIKEN AICSKiwamu Okabe @ RIKEN AICSKiwamu Okabe @ RIKEN AICSKiwamu Okabe @ RIKEN AICS

Are you ready?Are you ready?Are you ready?Are you ready?Are you ready?
Have you installed ATS2 compiler? If
not, please install the ATS2 into your
PC on following manual:
☆ In English: http://bit.ly/instats☆ In English: http://bit.ly/instats☆ In English: http://bit.ly/instats☆ In English: http://bit.ly/instats☆ In English: http://bit.ly/instats
☆ In Japanese: http://bit.ly/instatsj☆ In Japanese: http://bit.ly/instatsj☆ In Japanese: http://bit.ly/instatsj☆ In Japanese: http://bit.ly/instatsj☆ In Japanese: http://bit.ly/instatsj
Also, you can get a code of this slide at
following:
following:
following:
following:
following:
☆ http://bit.ly/ats20150306☆ http://bit.ly/ats20150306☆ http://bit.ly/ats20150306☆ http://bit.ly/ats20150306☆ http://bit.ly/ats20150306

Install ATS2 into Debian #1Install ATS2 into Debian #1Install ATS2 into Debian #1Install ATS2 into Debian #1Install ATS2 into Debian #1
☆ Get source code of ATS2 compiler☆ Get source code of ATS2 compiler☆ Get source code of ATS2 compiler☆ Get source code of ATS2 compiler☆ Get source code of ATS2 compiler
$ wget http://downloads.sourceforge.net/project/ats2-lang/ats2-
lang/ats2-postiats-0.1.9/ATS2-Postiats-0.1.9.tgz
$ wget http://downloads.sourceforge.net/project/ats2-lang-contrib/
ats2-lang-contrib/ATS2-Postiats-contrib-0.1.6.tgz
☆ Install packages needed by the ATS2☆ Install packages needed by the ATS2☆ Install packages needed by the ATS2☆ Install packages needed by the ATS2☆ Install packages needed by the ATS2
$ sudo apt-get install gcc libgc-dev libgmp-dev make$ sudo apt-get install gcc libgc-dev libgmp-dev make$ sudo apt-get install gcc libgc-dev libgmp-dev make$ sudo apt-get install gcc libgc-dev libgmp-dev make$ sudo apt-get install gcc libgc-dev libgmp-dev make

Install ATS2 into Debian #2Install ATS2 into Debian #2Install ATS2 into Debian #2Install ATS2 into Debian #2Install ATS2 into Debian #2
☆ Compile the ATS2 compiler☆ Compile the ATS2 compiler☆ Compile the ATS2 compiler☆ Compile the ATS2 compiler☆ Compile the ATS2 compiler
$ tar xf ATS2-Postiats-0.1.9.tgz
$ export PATSHOME=`pwd`/ATS2-Postiats-0.1.9
$ export PATH=${PATSHOME}/bin:${PATH}
$ tar xf ATS2-Postiats-contrib-0.1.6.tgz
$ export PATSHOMERELOC=`pwd`/ATS2-Postiats-contrib-0.1.6
$ cd ${PATSHOME}
$ ./configure
$ make
$ cd ${PATSHOME}
$ ./configure
$ make
$ cd ${PATSHOME}
$ ./configure
$ make
$ cd ${PATSHOME}
$ ./configure
$ make
$ cd ${PATSHOME}
$ ./configure
$ make
☆ Ready to compile ATS code!☆ Ready to compile ATS code!☆ Ready to compile ATS code!☆ Ready to compile ATS code!☆ Ready to compile ATS code!
$ patsopt --version
ATS/Postiats version 0.1.9 with Copyright (c) 2011-2015 Hongwei Xi
$ patsopt --version
$ patsopt --version
$ patsopt --version
$ patsopt --version

What is ATS?What is ATS?What is ATS?What is ATS?What is ATS?
http://www.ats-lang.org/http://www.ats-lang.org/http://www.ats-lang.org/http://www.ats-lang.org/http://www.ats-lang.org/
☆ Syntax like ML☆ Syntax like ML☆ Syntax like ML☆ Syntax like ML☆ Syntax like ML
☆ Dependent types☆ Dependent types☆ Dependent types☆ Dependent types☆ Dependent types
☆ Linear types☆ Linear types☆ Linear types☆ Linear types☆ Linear types
☆ Optional GC☆ Optional GC☆ Optional GC☆ Optional GC☆ Optional GC
☆ Without any runtime☆ Without any runtime☆ Without any runtime☆ Without any runtime☆ Without any runtime
☆ Successor of Dependent ML☆ Successor of Dependent ML☆ Successor of Dependent ML☆ Successor of Dependent ML☆ Successor of Dependent ML

What can ATS do?What can ATS do?What can ATS do?What can ATS do?What can ATS do?
☆ Proof code using dependent types☆ Proof code using dependent types☆ Proof code using dependent types☆ Proof code using dependent types☆ Proof code using dependent types
☆ Safely use malloc using linear types☆ Safely use malloc using linear types☆ Safely use malloc using linear types☆ Safely use malloc using linear types☆ Safely use malloc using linear types
☆ Safely use pointer using linear types☆ Safely use pointer using linear types☆ Safely use pointer using linear types☆ Safely use pointer using linear types☆ Safely use pointer using linear types
☆ Use strong type without any OS☆ Use strong type without any OS☆ Use strong type without any OS☆ Use strong type without any OS☆ Use strong type without any OS
☆ Write code on bare metal hardware☆ Write code on bare metal hardware☆ Write code on bare metal hardware☆ Write code on bare metal hardware☆ Write code on bare metal hardware
☆ Write code in Linux kernel☆ Write code in Linux kernel☆ Write code in Linux kernel☆ Write code in Linux kernel☆ Write code in Linux kernel

The goal of todayThe goal of todayThe goal of todayThe goal of todayThe goal of today
Already, ATS has some good documents.Already, ATS has some good documents.Already, ATS has some good documents.Already, ATS has some good documents.Already, ATS has some good documents.
* Introduction to Programming in ATS
http://ats-lang.sourceforge.net/DOCUMENT/INT2PROGINATS/HTML/
* A Tutorial on Programming Features in ATS
http://ats-lang.sourceforge.net/DOCUMENT/ATS2TUTORIAL/HTML/
* Effective ATS
http://ats-lang.sourceforge.net/EXAMPLE/EFFECTIVATS/
* Wiki for ATS2
https://github.com/githwxi/ATS-Postiats/wiki
* Effective ATS
* Wiki for ATS2
* Effective ATS
* Wiki for ATS2
* Effective ATS
* Wiki for ATS2
* Effective ATS
* Wiki for ATS2
However, they are sometimes hard for
beginner. The goal of today is to learn
to read "Introduction to Programming
in ATS" by yourself.

Hello WorldHello WorldHello WorldHello WorldHello World
$ vi helloworld.dats
val () = println! "Hello, world!"
implement main0 () = ()
$ patscc helloworld.dats
$ ./a.out
Hello, world!
$ ./a.out
Hello, world!
$ ./a.out
Hello, world!
$ ./a.out
Hello, world!
$ ./a.out
Hello, world!
You can call println! directly.You can call println! directly.You can call println! directly.You can call println! directly.You can call println! directly.
$ vi helloworld2.dats
implement main0 () = () where {
}
}
}
}
}
Or more simply...Or more simply...Or more simply...Or more simply...Or more simply...
implement main0 () = println! "Hello, world!"

IntegerIntegerIntegerIntegerInteger
The "share/atspre_staload.hats" is
needed by overloaded operators.
$ vi int_op.dats
#include "share/atspre_staload.hats"
val () = println! (3 + 4 * 2)
val () = println! ((3 + 4) * 2)
val () = println! (2 - 3)
val () = println! (7 / 2)
val () = println! (7 % 2)
$ patscc int_op.dats
$ ./a.out
11
14
-1
3
1
$ vi int_op.dats
val () = println! (3 + 4 * 2)
val () = println! ((3 + 4) * 2)
$ ./a.out
11
14
-1
3
1
$ vi int_op.dats
val () = println! (3 + 4 * 2)
val () = println! ((3 + 4) * 2)
$ ./a.out
11
14
-1
3
1
$ vi int_op.dats
val () = println! (3 + 4 * 2)
val () = println! ((3 + 4) * 2)
$ ./a.out
11
14
-1
3
1
$ vi int_op.dats
val () = println! (3 + 4 * 2)
val () = println! ((3 + 4) * 2)
$ ./a.out
11
14
-1
3
1

Zero DivisionZero DivisionZero DivisionZero DivisionZero Division
But, zero-division causes compile error!But, zero-division causes compile error!But, zero-division causes compile error!But, zero-division causes compile error!But, zero-division causes compile error!
$ vi divmod.dats
val () = println! (7 / (2 - 2))
$ patscc divmod.dats
/home/kiwamu/tmp/tmp/divmod.dats: 60(line=3, offs=22) -- 61
r
)))
typechecking has failed: there are some unsolved constraints:
please inspect the above reported error message(s) for information.
exit(ATS): uncaught exception:
_2home_2kiwamu_2src_2ATS_2dPostiats_2src_2pats_error_2esats__FatalE
rrorExn(1025)
$ vi divmod.dats
val () = println! (7 / (2 - 2))
r
)))
rrorExn(1025)
$ vi divmod.dats
val () = println! (7 / (2 - 2))
r
)))
rrorExn(1025)
$ vi divmod.dats
val () = println! (7 / (2 - 2))
r
)))
rrorExn(1025)
$ vi divmod.dats
val () = println! (7 / (2 - 2))
r
)))
rrorExn(1025)
The error message is hard to be read ...The error message is hard to be read ...The error message is hard to be read ...The error message is hard to be read ...The error message is hard to be read ...

Understanding internal typesUnderstanding internal typesUnderstanding internal typesUnderstanding internal typesUnderstanding internal types
Let's decode the error message that is
represented on following internal types:
https://github.com/githwxi/ATS-Postiats/wiki/Internal-types
* S2Eapp - an application term.
* S2Ecst - a type constant (for instance, int, bool, list, etc.)
* S2Eeff - function effects.
* S2Eexi - an existentially quantified type.
* S2Eint - machine precision integer.
* S2Eintinf - infinite precision integer; commonly used for
integer sorts in most compiled versions of atsopt (patsopt).
* S2Evar - a (typically universally quantified) variable.
* S2Etop (0; T) means T?
* S2Etop (1; T) means T?!
* S2EVar - an (existentially quantified) unification variable
introduced by the typechecker.

The zero division error means...The zero division error means...The zero division error means...The zero division error means...The zero division error means...
unsolved constraint: C3NSTRprop(main; S2Eapp(S2Ecst(!=); S2EVar
(4177->S2Eapp(S2Ecst(sub_int_int); S2EVar(4173->S2Eintinf(2)),
S2EVar(4174->S2Eintinf(2)))), S2Eintinf(0)))
↓ meaning
The proposition "2 - 2 != 0" is not solved.
↓ meaning
↓ meaning
↓ meaning
↓ meaning
It's powered by dependent types that
are used at ATS language's prelude.
$ vi ATS-Postiats/prelude/SATS/integer.sats
typedef
g1int_div_type
(tk:tk) =
{i,j:int | j != 0}
(g1int (tk, i), g1int (tk, j)) -<fun0> g1int (tk)
--snip--
fun g1int_div_int : g1int_div_type (intknd) = "mac#%"
fun g1int_div_lint : g1int_div_type (lintknd) = "mac#%"
fun g1int_div_llint : g1int_div_type (llintknd) = "mac#%"
fun g1int_div_ssize : g1int_div_type (ssizeknd) = "mac#%"
typedef
g1int_div_type
(tk:tk) =
{i,j:int | j != 0}
--snip--
typedef
g1int_div_type
(tk:tk) =
{i,j:int | j != 0}
--snip--
typedef
g1int_div_type
(tk:tk) =
{i,j:int | j != 0}
--snip--
typedef
g1int_div_type
(tk:tk) =
{i,j:int | j != 0}
--snip--

Real NumberReal NumberReal NumberReal NumberReal Number
$ vi double_op.dats
val () = println! ((3.0 + 5.0) * 8.0 / 3.0)
$ patscc double_op.dats
$ ./a.out
21.333333
$ vi double_op.dats
val () = println! ((3.0 + 5.0) * 8.0 / 3.0)
$ ./a.out
21.333333
$ vi double_op.dats
val () = println! ((3.0 + 5.0) * 8.0 / 3.0)
$ ./a.out
21.333333
$ vi double_op.dats
val () = println! ((3.0 + 5.0) * 8.0 / 3.0)
$ ./a.out
21.333333
$ vi double_op.dats
val () = println! ((3.0 + 5.0) * 8.0 / 3.0)
$ ./a.out
21.333333
The operators are overloaded.The operators are overloaded.The operators are overloaded.The operators are overloaded.The operators are overloaded.
$ vi double_int_op.dats
val () = println! ((3 + 5.0) * 8 / 3.0)
$ patscc double_int_op.dats
$ ./a.out
21.333333
val () = println! ((3 + 5.0) * 8 / 3.0)
$ ./a.out
21.333333
val () = println! ((3 + 5.0) * 8 / 3.0)
$ ./a.out
21.333333
val () = println! ((3 + 5.0) * 8 / 3.0)
$ ./a.out
21.333333
val () = println! ((3 + 5.0) * 8 / 3.0)
$ ./a.out
21.333333

Boolean valueBoolean valueBoolean valueBoolean valueBoolean value
$ vi bool_op.dats
val () = println! (true && false)
val () = println! (not (false || not false && not false))
val () = println! (2 < 3)
val () = println! (2 < 3 && 2.0 >= 3.0)
val () = println! (2 < 3 || 2.0 = 3.0)
val () = println! (not (3 < 2))
$ patscc bool_op.dats
$ ./a.out
false
false
true
false
true
true
$ vi bool_op.dats
val () = println! (2 < 3 && 2.0 >= 3.0)
val () = println! (2 < 3 || 2.0 = 3.0)
$ ./a.out
false
false
true
false
true
true
$ vi bool_op.dats
val () = println! (2 < 3 && 2.0 >= 3.0)
val () = println! (2 < 3 || 2.0 = 3.0)
$ ./a.out
false
false
true
false
true
true
$ vi bool_op.dats
val () = println! (2 < 3 && 2.0 >= 3.0)
val () = println! (2 < 3 || 2.0 = 3.0)
$ ./a.out
false
false
true
false
true
true
$ vi bool_op.dats
val () = println! (2 < 3 && 2.0 >= 3.0)
val () = println! (2 < 3 || 2.0 = 3.0)
$ ./a.out
false
false
true
false
true
true

Constant definitionConstant definitionConstant definitionConstant definitionConstant definition
$ vi val_overwrite.dats
implement main0 () = {
val a = 1
val b = a
val () = println! a
val () = println! b
val a = 2
val () = println! a
val () = println! b
}
$ patscc val_overwrite.dats
$ ./a.out
1
1
2
1
val a = 1
val b = a
val () = println! a
val () = println! b
val a = 2
val () = println! a
val () = println! b
}
$ ./a.out
1
1
2
1
val a = 1
val b = a
val () = println! a
val () = println! b
val a = 2
val () = println! a
val () = println! b
}
$ ./a.out
1
1
2
1
val a = 1
val b = a
val () = println! a
val () = println! b
val a = 2
val () = println! a
val () = println! b
}
$ ./a.out
1
1
2
1
val a = 1
val b = a
val () = println! a
val () = println! b
val a = 2
val () = println! a
val () = println! b
}
$ ./a.out
1
1
2
1

Function definitionFunction definitionFunction definitionFunction definitionFunction definition
$ vi two_arguments.dats
fun g (x:int, y:int): int = x * x + y * y - 4
implement main0 () = println! (g (3, 2))
$ patscc two_arguments.dats
$ ./a.out
9
$ ./a.out
9
$ ./a.out
9
$ ./a.out
9
$ ./a.out
9

TypecheckingTypecheckingTypecheckingTypecheckingTypechecking
$ vi f_takes_double.dats
fun f (x:int): int = 3 * x
val r = f 4.0
val () = println! r
}
$ patscc f_takes_double.dats
/home/kiwamu/tmp/tmp/f_takes_double.dats: 103(line=6, offs=14) --
106(line=6, offs=17): error(3): the dynamic expression cannot be
106(line=6, offs=17): error(3): mismatch of static terms (tyleq):
The actual term is: S2Eapp(S2Ecst(g0float_t0ype); S2Ecst
(double_kind))
The needed term is: S2Eapp(S2Ecst(g0int_t0ype); S2Ecst(int_kind))
val r = f 4.0
val () = println! r
}
(double_kind))
val r = f 4.0
val () = println! r
}
(double_kind))
val r = f 4.0
val () = println! r
}
(double_kind))
val r = f 4.0
val () = println! r
}
(double_kind))
Function "f" should take value of int.Function "f" should take value of int.Function "f" should take value of int.Function "f" should take value of int.Function "f" should take value of int.

Conditional branchConditional branchConditional branchConditional branchConditional branch
$ vi if_then_else.dats
val a = if 1 < 2 then 3 else 4
val () = println! (a:int)
}
$ patscc if_then_else.dats
$ ./a.out
3
}
$ ./a.out
3
}
$ ./a.out
3
}
$ ./a.out
3
}
$ ./a.out
3

Able to drop else clauseAble to drop else clauseAble to drop else clauseAble to drop else clauseAble to drop else clause
$ vi println_expr.dats
implement main0 () = if 7 > 5 then println! "It's true."
$ patscc println_expr.dats
$ ./a.out
It's true.
$ ./a.out
It's true.
$ ./a.out
It's true.
$ ./a.out
It's true.
$ ./a.out
It's true.

Showing typesShowing typesShowing typesShowing typesShowing types
$ vi showtype_int.dats
val () = println! 3
val _ = $showtype 3
$ patscc showtype_int.dats
**SHOWTYPE[UP]**(/home/kiwamu/tmp/tmp/showtype_int.dats: 39
(line=2, offs=19) -- 40(line=2, offs=20)): S2Eapp(S2Ecst
(g1int_int_t0ype); S2Ecst(int_kind), S2Eintinf(3)): S2RTbas
(S2RTBASimp(1; t@ype))
$ ./a.out
3
val () = println! 3
val _ = $showtype 3
$ ./a.out
3
val () = println! 3
val _ = $showtype 3
$ ./a.out
3
val () = println! 3
val _ = $showtype 3
$ ./a.out
3
val () = println! 3
val _ = $showtype 3
$ ./a.out
3
"Wiki for ATS2" explains "$showtype"."Wiki for ATS2" explains "$showtype"."Wiki for ATS2" explains "$showtype"."Wiki for ATS2" explains "$showtype"."Wiki for ATS2" explains "$showtype".
"$showtype" prints out the type of a value or variable in ATS's
internal type representation. Very helpful for understanding type
errors, but the exact meaning of the output can still be cryptic
for more complicated cases.

Immutable stringImmutable stringImmutable stringImmutable stringImmutable string
$ vi print_foo.dats
val () = println! "foo"
$ patscc print_foo.dats
$ ./a.out
foo
$ vi print_foo.dats
$ ./a.out
foo
$ vi print_foo.dats
$ ./a.out
foo
$ vi print_foo.dats
$ ./a.out
foo
$ vi print_foo.dats
$ ./a.out
foo
However, immutable string can't do
such like following:
☆ append☆ append☆ append☆ append☆ append
☆ reverse☆ reverse☆ reverse☆ reverse☆ reverse

Try to use mutable stringTry to use mutable stringTry to use mutable stringTry to use mutable stringTry to use mutable string
$ vi try_string_append.dats
val s3 = string_append ("Yokohama", "Station")
val () = println! s3
}
$ patscc try_string_append.dats
/home/kiwamu/tmp/try_string_append.dats: 60(line=3, offs=22) -- 135
(line=6, offs=2): error(3): the linear dynamic variable [s3$3509
(-1)] needs to be consumed but it is preserved with the type
[S2Eapp(S2Ecst(strptr_addr_vtype); S2EVar(4175))] instead.
patsopt(TRANS3): there are [1] errors in total.
rrorExn(1025)
}
rrorExn(1025)
}
rrorExn(1025)
}
rrorExn(1025)
}
rrorExn(1025)
Why does error occur?Why does error occur?Why does error occur?Why does error occur?Why does error occur?

Need to free mutable stringNeed to free mutable stringNeed to free mutable stringNeed to free mutable stringNeed to free mutable string
$ vi string_append.dats
val () = free s3
}
$ patscc string_append.dats -DATS_MEMALLOC_LIBC
$ ./a.out
YokohamaStation
val () = free s3
}
$ ./a.out
YokohamaStation
val () = free s3
}
$ ./a.out
YokohamaStation
val () = free s3
}
$ ./a.out
YokohamaStation
val () = free s3
}
$ ./a.out
YokohamaStation
The "ATS_MEMALLOC_LIBC" flag is
needed to use malloc on libc.
How can ATS2 know failure of free?How can ATS2 know failure of free?How can ATS2 know failure of free?How can ATS2 know failure of free?How can ATS2 know failure of free?

Linear type watches resourceLinear type watches resourceLinear type watches resourceLinear type watches resourceLinear type watches resource

Type of ListType of ListType of ListType of ListType of List

Create listCreate listCreate listCreate listCreate list
$ vi make_pair.dats
val l = list_vt_make_pair (1, 2)
val () = print_list_vt<int> l
val () = list_vt_free<int> l
}
$ patscc make_pair.dats -DATS_MEMALLOC_LIBC
$ ./a.out
1, 2
$ vi make_pair.dats
}
$ ./a.out
1, 2
$ vi make_pair.dats
}
$ ./a.out
1, 2
$ vi make_pair.dats
}
$ ./a.out
1, 2
$ vi make_pair.dats
}
$ ./a.out
1, 2
The "<int>" is needed to use template
function.
function.
function.
function.
function.

Create list as figureCreate list as figureCreate list as figureCreate list as figureCreate list as figure

Append listAppend listAppend listAppend listAppend list
$ vi append_list.dats
val l1 = list_vt_make_pair (1, 2)
val l2 = list_vt_make_sing 3
val l3 = list_vt_append (l2, l1)
val () = print_list_vt<int> l3
val () = list_vt_free<int> l3
}
$ patscc append_list.dats -DATS_MEMALLOC_LIBC
$ ./a.out
3, 1, 2
}
$ ./a.out
3, 1, 2
}
$ ./a.out
3, 1, 2
}
$ ./a.out
3, 1, 2
}
$ ./a.out
3, 1, 2

Append list as figureAppend list as figureAppend list as figureAppend list as figureAppend list as figure

Join "Japan ATS User Group" !Join "Japan ATS User Group" !Join "Japan ATS User Group" !Join "Japan ATS User Group" !Join "Japan ATS User Group" !
http://jats-ug.metasepi.org/http://jats-ug.metasepi.org/http://jats-ug.metasepi.org/http://jats-ug.metasepi.org/http://jats-ug.metasepi.org/
We translate following ATS documents
into Japanese.
into Japanese.
into Japanese.
into Japanese.
into Japanese.
* ATSプログラミング入門
http://jats-ug.metasepi.org/doc/ATS2/INT2PROGINATS/
* ATSプログラミングチュートリアル
http://jats-ug.metasepi.org/doc/ATS2/ATS2TUTORIAL/
* Effective ATS
https://github.com/jats-ug/translate/blob/master/Manual/
EffectiveATS.md
* Effective ATS
EffectiveATS.md
* Effective ATS
EffectiveATS.md
* Effective ATS
EffectiveATS.md
* Effective ATS
EffectiveATS.md
Join us and review it!Join us and review it!Join us and review it!Join us and review it!Join us and review it!

ATS Programming Tutorial

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