Solving “Same Fringe” with Stream Generators
A classic problem in concurrent programming is known as the “same fringe” problem [1]. What is the same fringe problem? As described by Richard Gabriel [2]: The samefringe problem is this: two binary...
View Article“Dining Philosophers” in Humus
The “Dining Philosophers” problem is a classic example used to illustrate various challenges with concurrency. We will approach this problem by incrementally designing the actors which model the...
View ArticleEvaluating Expressions, part 3 – Pairs and Parallelism
In part 3 of our series implementing programming language constructs with actors, we explore parallel evaluation of sub-expressions and introduce pairs. Pairs allow the construction of tuples,...
View ArticleEvaluating Expressions, part 7 – Transactions and Exceptions
In part 7 of our series implementing programming language constructs with actors, we implement parallel execution of block statements. Parallel execution motivates the use of single-assignment...
View ArticlePlaying the Stooge with Humus
Happy New Year and welcome to 2011. With the coming of the new year, I’m happy to announce the availability of a simulator/debugger environment for Humus, currently hosted at...
View ArticleImplementing Actors in Kernel
Now is the time we come full-circle in our exploration of Kernel/Scheme/LISP and show how Actors can be implemented on this foundation. This should dispel the notion that Actors are just...
View ArticleFutures and Capabilities
In the Actor Model, concurrency is the default. Sequencing must by arranged explicitly. An important case of sequencing occurs when there is a data dependency between different parts of a system. One...
View Article“Sleeping Barber” in Humus
The “Sleeping Barber” problem is another classic concurrency example. As with our previous discussion of “Dining Philosophers”, actors allow a novel approaching to solving this problem. We will adjust...
View Article“Same Fringe” Revisited
The fringe of a binary tree is simply the sequence of leaves reading from left to right [1]. Comparing the fringe of two binary trees to see if they are the same has been described as the simplest...
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