Exceptions are an important feature of modern programming languages, but their compilation has traditionally been viewed as an advanced topic. In this article we show that the basic method of compiling exceptions using stack unwinding can be explained and verified both simply and precisely, using elementary functional programming techniques. In particular, we develop a compiler for a small lang...

In recent years there has been much interest in the idea of concurrent programming using transactional memory, for example as provided in STM Haskell. While programmers are provided with a simple high-level model of transactions in terms of a stop-the-world semantics, the low-level implementation is rather more complex, involving subtle techniques that allow multiple transactions to execute con...

We consider the problem of adding two n-bit numbers which are chosen independently and uniformly at random where the adder is a circuit of AND, OR, and NOT gates of fan-in two. The fastest currently known worst-case adder has running time logn +O( p logn) [Khr]. We rst present a circuit which adds at least 1 fraction of pairs of numbers correctly and has running time log log ( n ) +O( p log log...