The document discusses the concept of language composition in programming, emphasizing the need for high performance, good syntactic integration, and minimal engineering effort. It critiques existing composition methods for their limitations in syntactic integration and performance, proposing a solution involving meta-tracing and language boxes to facilitate better integration between different programming languages. The authors provide examples and outline the challenges faced in both syntactic and runtime composition, ultimately illustrating their proposed solution for effective language composition.

1. Language Composition
A Case Study in Cross-Language Tracing
Edd Barrett
Carl
Friedrich
Bolz
Laurence
Tratt
Naveneetha
Krishnan
Vasudevan
Lukas
Diekmann
Software Development Team
2013-11-13
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2. Life is Good
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3. Life is Good
3D Engine
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4. Life is Good
Mobile App
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5. Life is Good
Quick Script
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6. That is, until...
// A load of Android Java code...
// find pairs where i + j < 10
Arraylist<int> result = new ArrayList();
for (int i : ints1) {
for (int j : ints2) {
if (i + j < 10) {
ArrayList<int> n = new ArrayList();
n.add(i);
n.add(j);
result.add(n);
}
}
}
// More Android Java code...
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7. That is, until...
// A load of Android Java code...
# find pairs where i + j < 10 in *Python*
result = [
(i, j) for i in ints1 for j in ints2
if i + j < 10
]
// More Android Java code...
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8. Or until...
# Some Python code...
if first == 1:
if second == 1:
return 999
elif second == 2:
return 666
else:
raise TrollException("naughty")
elif first == 2:
if second == 1:
return 1337
elif second == 2:
return 42
else:
raise TrollException("naughty")
else:
raise TrollException("naughty")
# More Python code...
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9. Or until...
# Some Python code...
(* Much easier to use pattern matching from functional
world, e.g. Ocaml *)
match (first, second) with
| (1, 1) -> 999
| (1, 2) -> 666
| (2, 1) -> 1337
| (2, 2) -> 42
| _ -> raise (TrollException "naughty");;
# More Python code...
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10. So what is my point?
THE POINT:
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11. So what is my point?
THE POINT:
PL Wars!
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12. So what is my point?
THE POINT:
PL Wars!
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13. So what is my point?
THE POINT:
It would be sweet to compose
programming languages.
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14. Language Composition
PL X
PL Z
PL Y
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15. Not a New Idea
Existing composition methods:
Poor syntactic integration.
Stringly-typed.
Languages not born equal.
One language hosts the other.
Poor performance
No cross-language optimisations.
Too much engineering effort.
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16. What do we want from a language
composition?
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17. What do we want from a language composition?
High performance
PL
>>>
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18. What do we want from a language composition?
Good syntactic integration
pl x
pl z
pl y
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19. What do we want from a language composition?
Little effort
<
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20. Breaking down the problem
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21. Breaking Down the Problem
PL X
PL Z
PL Y
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22. Breaking Down the Problem
syntax
PL X
syntax
runtime
PL Z
syntax
runtime
PL Y
runtime
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23. Challenges: Syntactic Composition
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24. Parsing
PL X
<grammar>
expr::= ...
term::= ...
| ...
| ...
func ::= ...
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25. Parsing
PL X
<grammar>
expr::= ...
term::= ...
| ...
| ...
func ::= ...
PL X
<program>
for (j : js) {
doStuff();
}
.
.
.
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26. Parsing
PL X
<grammar>
expr::= ...
term::= ...
| ...
| ...
func ::= ...
Parsing
PL X
<program>
for (j : js) {
doStuff();
}
.
.
.
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27. Parsing
PL X
<grammar>
expr::= ...
term::= ...
| ...
| ...
func ::= ...
Parsing
PL X
<program>
Parse Tree
for (j : js) {
doStuff();
}
.
.
.
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28. Parsing
PL X
<grammar>
expr::= ...
term::= ...
| ...
| ...
func ::= ...
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29. Parsing
PL X
<grammar>
expr::= ...
term::= ...
| ...
| ...
func ::= ...
PL Y
<grammar>
expr::= ...
term::= ...
| ...
| ...
func ::= ...
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30. Parsing
PL X
<grammar>
expr::= ...
term::= ...
| ...
| ...
func ::= ...
PL Y
<grammar>
PL Z
<grammar>
expr::= ...
term::= ...
| ...
| ...
func ::= ...
expr::= ...
term::= ...
| ...
| ...
func ::= ...
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31. Parsing
PL X
<grammar>
expr::= ...
term::= ...
| ...
| ...
func ::= ...
PL Y
<grammar>
AMBI
GUOU
S
PL Z
<grammar>
expr::= ...
term::= ...
| ...
| ...
func ::= ...
expr::= ...
term::= ...
| ...
| ...
func ::= ...
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32. Parsing
PL Z
<grammar>
AM
expr::= ...
term::= ...
| ...
| ...
func ::= ...
BI
GU
OU
S
PL Z
<program>
Parsing
for (j : js) {
doStuff();
}
.
.
.
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?
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33. Challenges: Runtime Composition
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34. Challenges: Runtime Composition
PL X
PL Y
Interpreter
Interpreter
C/C++
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35. Challenges: Runtime Composition
PL X
To
o
Interpreter
PL Y
sl Interpreter
ow
C/C++
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36. Challenges: Runtime Composition
JIT Compiler
JIT Compiler
PL X
PL Y
Interpreter
Interpreter
C/C++
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37. Challenges: Runtime Composition
JIT Compiler
JIT Compiler
PL e Too
X
n
PL Y
gi
mu Interpreter
ne ch
er
in
g
Interpreter
C/C++
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38. Challenges: Runtime Composition
PL X
PL Y
Interpreter
Interpreter
JVM/CLR
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JIT Compiler
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39. Challenges: Runtime Composition
fo Poo
r
r
dy pe
na
Interpreter rfo
Interpreter
mi
rm
c
la anc
ng e
ua
ge
s
JIT Compiler
PL X
PL Y
JVM/CLR
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40. Our Proposed Solution
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41. Proposed solution
Meta-tracing + Language Boxes
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42. Meta-tracing
Meta-tracing
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43. PL
Interpreter
Meta-tracing
Meta-tracing
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PL
Interpreter
Tracing JIT
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44. PL X
PL Y
Interpreters
Glue
Meta-tracing
RPython
Meta-tracing
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PL Z
Interpreter
Tracing JIT
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45. PL X
PL Y
Meta-tracing
Meta-tracing
PL Z
Good perfo
rmance
Interpreters
Glue
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Interpreter
Tracing JIT
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46. PL X
PL Y
Meta-tracing
Meta-tracing
PL Z
Good perfo
rmance
Interpreters
Glue
Interpreter
Tracing JIT
Little effort
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47. Meta-tracing
Language Boxes
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48. Language Boxes Editor
Suppose we want to write a Java + SQL program.
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49. Language Boxes Editor
Suppose we want to write a Java + SQL program.
Begin writing Java code
for (string s :
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50. Language Boxes Editor
Suppose we want to write a Java + SQL program.
for (string s :
Open SQL language box
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51. Language Boxes Editor
Suppose we want to write a Java + SQL program.
Write SQL code
for (string s :
SELECT * FROM tbl WHERE
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52. Language Boxes Editor
Suppose we want to write a Java + SQL program.
SELECT * FROM tbl WHERE
name = this.name;) {
for (string s :
Java code
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53. Language Boxes Editor
Suppose we want to write a Java + SQL program.
Good Syntact
ic Integrati
on
SELECT * FROM tbl WHERE
name = this.name;) {
for (string s :
Java code
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54. Language Boxes Editor
Suppose we want to write a Java + SQL program.
Good Syntact
ic Integrati
on
SELECT * FROM tbl WHERE
name = this.name;) {
y
for (string s :
Avoids Ambiguit
Java code
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55. Language Boxes Editor
Suppose we want to write a Java + SQL program.
Good Syntact
ic Integrati
on
NeedSELECT omFROM tbl WHERE
for (string s : s Cust *
Editor
name = this.name;) {
Avoids Ambiguity
Java code
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56. Our First Composition
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57. Unipycation
Interpreters
Glue
Unipycation
Prolog
RPython
Python
Interpreter
Tracing JIT
+ our language box editor (eco)
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58. Thanks
SELECT * FROM tbl WHERE
name = this.name;) {
for (string s :
Java code
Interpreters
Glue
Unipycation
Prolog
RPython
Python
Interpreter
Tracing JIT
http://soft-dev.org
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