How can a system that differs sharply from all currently fashionable approaches score any kind of success? Here's how.

Linda in context

Since the early 1960's, researchers have built a number of programming languages and environments with the intention of making programming accessible to a larger number of people. This article presents a taxonomy of languages and environments designed to make programming more accessible to novice programmers of all ages. The systems are organized by their primary goal, either to teach programming or to use programming to empower their users, and then, by each system's authors' approach, to making learning to program easier for novice programmers. The article explains all categories in the taxonomy, provides a brief description of the systems in each category, and suggests some avenues for future work in novice programming environments and languages.

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Lowering the barriers to programming: A taxonomy of programming environments and languages for novice programmers

No wonder you activities are, reading will be always needed. It is not only to fulfil the duties that you need to finish in deadline time. Reading will encourage your mind and thoughts. Of course, reading will greatly develop your experiences about everything. Reading molecular biology of the gene is also a way as one of the collective books that gives many advantages. The advantages are not only for you, but for the other peoples with those meaningful benefits.

Molecular Biology of the Gene.

The programming language aspects of a graphic simulation laboratory named ThingLab are presented. The design and implementation of ThingLab are extensions to Smalltalk. In ThingLab, constraints are used to specify the relations that must hold among the parts of the simulation. The system is object-oriented and employs inheritance and part-whole hierarchies to describe the structure of a simulation. An interactive, graphic user interface is provided that allows the user to view and edit a simulation.

The Programming Language Aspects of ThingLab, a Constraint-Oriented Simulation Laboratory

In previous heap storage systems, the cost of creating objects and garbage collection is independent of the lifetime of the object. Since objects with short lifetimes account for a large portion of storage use, it is worth optimizing a garbage collector to reclaim storage for these objects more quickly. The garbage collector should spend proportionately less effort reclaiming objects with longer lifetimes. We present a garbage collection algorithm that (1) makes storage for short-lived objects cheaper than storage for long-lived objects, (2) that operates in real time—object creation and access times are bounded, (3) increases locality of reference, for better virtual memory performance, (4) works well with multiple processors and a large address space.

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A real-time garbage collector based on the lifetimes of objects

Squeak is an open, highly-portable Smalltalk implementation whose virtual machine is written entirely in Smalltalk, making it easy to. debug, analyze, and change. To achieve practical performance, a translator produces an equivalent C program whose performance is comparable to commercial Smalltalks.Other noteworthy aspects of Squeak include: a compact object format that typically requires only a single word of overhead per object; a simple yet efficient incremental garbage collector for 32-bit direct pointers; efficient bulk-mutation of objects; extensions of BitBlt to handle color of any depth and anti-aliased image rotation and scaling; and real-time sound and music synthesis written entirely in Smalltalk.

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Back to the future: the story of Squeak, a practical Smalltalk written in itself

This paper describes a programming system based on the metaphor of communicating objects. Experience with a running system shows that this model provides flexibility, modularity and compactness. A compiled representation for the language is presented, along with an interpreter suitable for microcoding. The object-oriented model provides naturally efficient addressing; a corresponding virtual memory is described which offers dense utilization of resident space.

https://wiki.squeak.org/squeak/uploads/400/Smalltalk-76.pdf

The Smalltalk-76 programming system design and implementation

Fabrik is a visual programming environment - a kit of computational and user-interface components that can be “wired” together to build new components and useful applications. Fabrik diagrams utilize bidirectional dataflow connections as a shorthand for multiple paths of flow. Built on object-oriented foundations. Fabrik components can compute arbitrary objects as outputs. Music and animation can be programmed in this way and the user interface can even be extended by generating graphical structures that depend on other data. An interactive type system guards against meaningless connections. As with simple dataflow, each Fabrik component can be compiled into an object with access methods corresponding to each of the possible paths of data propagation.

Fabrik: a visual programming environment

Smalltalk classes may be arranged in hierarchies, so that a class can inherit the properties of another class. In the standard Smalltalk language, a class may inherit from only one other class. In this paper we describe an implementation of multiple inheritance in Smalltalk.

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Multiple inheritance in smalltalk-80

Certain situations arise in programming that lead to multiply polymorphic expressions, that is, expressions in which several terms may each be of variable type. In such situations, conventional object-oriented programming practice breaks down, leading to code which is not properly modular. This paper describes a simple approach to such problems which preserves all the benefits of good object-oriented programming style in the face of any degree of polymorphism. An example is given in Smalltalk-80 syntax, but the technique is relevant to all object-oriented languages.

Daniel H. H. Ingalls

Papers

Back to the future: the story of Squeak, a practical Smalltalk written in itself

The Smalltalk-76 programming system design and implementation

Fabrik: a visual programming environment

Multiple inheritance in smalltalk-80

A simple technique for handling multiple polymorphism