Columbia University Programming Languages and Translators Spring 2007 Professor Edwards Semester Project Proposal Steve Henderson Levi Lister Abe Skolnik Wei Teng SLAWscript Language Proposal Page 2 of 4 Executive Summary Two modes Text simplified Python GUI HyperCard for the Java age Introduction The name of our language is SLAWscript Steve Levi Abe and Wei s scripting language SLAWscript is a general purpose yet simple scripting language designed to enable the easy production of either text i e command line environment applications or GUI applications that are made of dialog boxes optionally with custom graphics Amongst other possible uses it will allow for quickly programming and deploying interactive training tutorial and survey applications SLAWscript is modeled on Python but on a smaller scale SLAWscript has no arrays classes or objects At this time only the three standard UNIX like channels stderr stdin and stdout are accessible that is to say files cannot be opened and used Also SLAWscript is not strict about the use of leading spacing Fundamental Need The Java Swing Application Programming Interface API provides a rich set of Graphical User Interface GUI widgets that can create useful and intuitive GUI interfaces Because such interfaces are based on Java they are highly portable and deployable and thus are desirable for mixed OS mixed CPU architecture communities However Swing requires considerable Java knowledge and experience to create a functional GUI application This can prevent a non Swing savvy researcher engineer or other programmer from experiencing the benefits of Swing For example a seventh grade music teacher may want to quickly design a GUI based tutorial for reviewing musical notation He or she envisions a series of windows where the student reviews and demonstrates knowledge of musical notation However although the teacher is highly familiar with the content of the tutorial he or she has no idea how to implement it He or she doesn t have the time to learn Swing or another language s GUI library and needs a custom solution with per student question generation and answer processing that cannot be performed or cannot be easily performed with common presentation tools such as Microsoft PowerPoint We are developing SLAWscript to address this need SLAWscript allows a designer to use a simple scripting language to develop a program that may use a series of customizable dialog boxes that interact with an end user SLAWscript allows a programmer to focus primarily on the content of the application and to use SLAWscript s program control logic to specify how the application should behave based on user input The more complicated aspects of Swing applications component layout event handling etc are handled by the SLAWscript implementation SLAWscript Language Proposal Page 3 of 4 Key Features Conventional SLAWscript attempts to use conventional notation where possible as limited by the expressive abilities of ASCII For example the bar symbol is used to both begin and end an operator which returns either the absolute value for numeric operands or the string length for string operands Dynamic In SLAWscript variables don t need to be declared and they are allowed to contain different data types at different points in time Flexible In SLAWscript the addition operator can take either a number or string as either of its parameters and intelligently decides whether to perform arithmetic addition or string concatenation The multiplication operator is similarly flexible and intelligently decides whether to perform arithmetic multiplication or string multiplication i e multiplying 3 by Hi produces HiHiHi In general wherever a number is required a variable containing a string containing an appropriate number may be used instead The primary exception assert statements This allows for easier use of user entered numbers in SLAWscript programs For example if the user entered 3 in response to a prompt and that string is stored in a variable called input then the expression 10 input yields the number seven Interpreted Our implementation of SLAWscript is an interpreter which facilitates rapid development Intuitive SLAWscript is designed to use the English language as a basis whenever it is helpful to do so for example to copy the data from a variable named a to a variable named b simply use the command copy a to b Portable and architecture neutral Our implementation of SLAWscript is based on Java which gets us for free the advantages that it should be able to run correctly on many different operating systems and CPU types Reduced ambiguity In SLAWscript the equals sign means only one thing test for equality Copying data unchanged from one variable to another can be done with the copy verb and general purpose assignment can be accomplished with the set verb SLAWscript Language Proposal Page 4 of 4 Representative program One representative program is an exam preparation assistant for a course in the humanities such as a history course Many of these tests require memorization of large amounts of information SLAWscript can easily be used to create a program to act as an interactive practice exam This practice exam would involve a series of text prompts or dialog boxes that display practice questions prompting for student input after each question SLAWscript s control logic allows the test designer to then branch and evolve the exam based on the student s input For example if the student answers incorrectly hints can be presented to aid in memorization Or if the student is mastering the questions corresponding to a certain level of difficulty the test can provide more difficult questions thus adapting to the individual student A study guide for a typical Art Humanities course is already in the early prototype stage The plan for this program is for it to act as a set of interactive flash cards by for each available picture displaying a picture of a painting and presenting appropriate multiple choice questions and then responding appropriately depending on whether the user answers correctly or incorrectly Examples of Syntax set a to 9 this is how we load a literal value set a to a 1 this is how we increment a variable copy a to b this is how we copy from one variable to another put b to stdout this is how we print put b n to stdout this is how we println the CLI way to ask a question and get the user s answer put What is your favorite color to stdout get color from stdin the GUI way to do it
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