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termine:ss16:160706 [04.07.2016 19:56] (current)
peter created
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 +====== 06.07.2016 - Sebastian Schweizer ======
 +
 +^ Time       | 09:00    |
 +^ Room       | 34-420 ​  |
 +
 +===== Title =====
 +
 +Lifetime Analysis for Whiley
 +
 +===== Abstract =====
 +
 +Safety critical environments require high programming standards.
 +//​Verification//​ is a way to prove absence of certain faults and to make
 +sure that a program meets a given specification. Unfortunately,​ most
 +modern programming languages do not actively support verification.
 +External tools are necessary and there is no good integration with the
 +development process.
 +
 +//Whiley// is a programming language that aims to popularize verification.
 +Functions can be annotated with pre- and postconditions and the compiler
 +ships with a verifier that ensures that the implementation satisfies the
 +specification. Verification is automatic, the programmer only needs to
 +provide loop invariants. Verified //Whiley// programs are guaranteed to be
 +free of runtime failures like index-out-of-bounds access in arrays and
 +nullpointer dereferences.
 +
 +//Rust// is a new programming language that aims to be fast and safe, and
 +it is classified as a systems programming language. //Rust// introduces a
 +revolutionary concept of //​ownership//​ and //​lifetimes//​ that allows for
 +automatic and safe memory management without using garbage collection. A
 +lifetime roughly states how long a dynamically allocated portion of
 +memory can be used. Each allocation belongs to a unique owner, and as
 +soon as the owner’s lifetime ends the memory will be freed, without the
 +need for garbage collection. Memory safety is guaranteed by using static
 +checks at compile time.
 +
 +This thesis extends the //Whiley// programming language to introduce a
 +concept of lifetimes similar to //Rust//. But both programming languages
 +have a different focus. We therefore need to adapt the concept such that
 +it fits //​Whiley//​’s environment. Our extension involves changes to the
 +language syntax and several parts of the compiler and intermediate code
 +formats. A main challenge is the treatment of lifetimes for subtyping
 +with recursive types and in method invocations.
 +
 +//Whiley// currently compiles to bytecode for the //Java Virtual Machine
 +(JVM)//, using its garbage collector to deallocate memory. There is an
 +experimental compiler for //Whiley// that generates //C// code, but it is
 +not yet able to deallocate dynamically allocated memory. We show how the
 +compiler can use lifetimes for memory management without garbage
 +collection, though the actual implementation for this part is left as
 +future work. This allows one to greatly improve the //Whiley// to //C//
 +compiler, which is necessary to run //Whiley// programs on embedded
 +devices that do not have enough resources to execute the //JVM//.
 +
 +
  
termine/ss16/160706.txt · Last modified: 04.07.2016 19:56 by peter