Florian Schanda

1. Ada 202x
A broad overview of relevant news
1st November, 2016
HIS 2016
Altran UK Limited
Florian Schanda
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2. Introduction
Apologies
Anish Mohammed (Ripple Labs) could sadly not attend - this is
not his talk.
Instead some news from the Ada language design group!
Overall direction
New language features
Potential language features
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3. Ada 202x
Broad direction
’95 Polymorphism, Protected objects, and many more
2005 Interfaces, Ravenscar, Assertions, Containers
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4. Ada 202x
Broad direction
’95 Polymorphism, Protected objects, and many more
2005 Interfaces, Ravenscar, Assertions, Containers
2012 Contracts (and richer expressions)
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5. Ada 202x
Broad direction
’95 Polymorphism, Protected objects, and many more
2005 Interfaces, Ravenscar, Assertions, Containers
2012 Contracts (and richer expressions)
202x Parallelism (and richer expressions)
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6. Ada 202x
Parallelism
Todays architectures are increasingly multi-core
GPU based solutions are an extreme example
It’s notoriously difficult to get this right
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7. Ada 202x
Parallelism
Todays architectures are increasingly multi-core
GPU based solutions are an extreme example
It’s notoriously difficult to get this right
Ada should make this easy!
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8. Ada 202x
Parallelism
The parallel block statement:
parallel
P := Compute_Prime (Bits => 4096 ,
RNG => "/dev/random");
and
Q := Compute_Prime (Bits => 4096 ,
RNG => "/dev/random");
end parallel;
parallel
N := P * Q;
and
Phi := (P - 1) * (Q - 1);
end parallel;
parallel
Public_Key := Make_Public_Key (N, Phi );
and
Private_Key := Make_Private_Key (N, Phi);
end parallel;
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9. Ada 202x
Parallelism
Something similar is planned for parallel loops. Three parts:
Optional declaration of storage for each chunk
Loop
Optional reduction
parallel
Sum : array (<>) of Integer := (others => 0);
−− Size of loop array depends on number of chunks
for I in 1 .. 1_000_000 loop
Sum (<>) := Sum (<>) + A (I); −− Write to the current chunk’s sum
then
Answer := 0;
for Value of Sum loop
Answer := Answer + Value;
end loop;
end loop;
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10. Ada 202x
Expressions
Short-hand for the left-hand-side of an assignment:
Database. Current_Instance (N). Usage_Count := @ + 1;
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11. Ada 202x
Expressions
Short-hand for the left-hand-side of an assignment:
Database. Current_Instance (N). Usage_Count := @ + 1;
More flexible than += or similar short-hands found in other
languages:
Arr (X + Y) := (if @ < Integer ’Last
then @ + 1
else Integer ’First );
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12. Ada 202x
Expressions
Delta aggregates replace Spark update expressions:
procedure Adjust (R : in out Record_T;
Fudge : Float)
with Post => R = (R’Old with delta
Low_Bound => Fudge * R’Old.Low_Bound ,
Hi_Bound => Fudge * R’Old.Hi_Bound );
−− We now know all other fields *do not* change
Also quite useful in non-contract code:
All_Zero : constant Array_T := (others => 0);
Mask : constant Array_T := (All_Zero with delta
A .. B => 1,
C .. D => 1);
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13. Ada 202x
Tasking
New aspect Nonblocking
New aspect Max Entry Queue Length
Extended Ravenscar profile
Multiple entries
Relative delay
Support for Ada.Calendar and implicit heap allocations
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14. Ada 202x
Other possible features
Let expressions
Lambda functions
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15. Ada 202x
Other possible features
Let expressions
Lambda functions
Generator subprograms (a limited form of co-routines)
yield 0; −− Return to calling subprogram, resume execution here
yield X;
These are iterable:
for Values of My_Generator loop
−− First we get 0, then we get X, ...
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16. Ada 202x
Other possible features
Let expressions
Lambda functions
Generator subprograms (a limited form of co-routines)
yield 0; −− Return to calling subprogram, resume execution here
yield X;
These are iterable:
for Values of My_Generator loop
−− First we get 0, then we get X, ...
Container aggregates and displays
S : Hash_Set := (X, Y, Z);
P : Hash_Set := (for N in Positive if Is_Prime (N) => N);
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17. Ada 202x
Conclusion
Parallelism
More expressions (better contracts)
Many of these will make it into Spark
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