1. Scripting Languages Intro Jan Stelovsky, ICS 215

2. Wikipedia • A scripting language, script language or extension language is a programming language that allows control of one or more software applications. • "Scripts" are distinct from the core code of the application, as they are usually written in a different language and are often created or at least modified by the end-user. • Scripts are often interpreted from source code or bytecode, whereas the applications they control are traditionally compiled to native machine code. • Scripting languages are nearly always embedded in the applications they control.

3. Comment • from stackoverflow: • You will notice the use of "usually", "often", "traditionally" and "nearly always" - these all tell you that there is no set of distinct attributes that make a specific language a "scripting language".

4. Scripting vs. “Programming” Languages • Scripting languages are Programming languages (PL) • interpreted vs. compiled • slow vs. fast • but: Java – a PL is hybrid • compiled to bytecode • bytecode is common to all hardware platforms • bytecode is then interpreted • JIT even compiles to “native” code dynamically • but: LISP – a PL - is interpreted • but: scripting languages became hybrid/compiled • all JavaScript scripts are nowadays compiled

5. Hybrid Processing program script bytecode nativeWindows Intel nativeMac Intel/Motorola nativeLinux Intel

6. Scripting vs. “Programming” Languages cont. • scripting languages often operate other programs, or the operating system (OS), e.g. Windows, or other applications, e.g. the browser • batch “shells” on Unix • Applescript operating other applications • but often programs in PL can execute or at least create scripts for scripting languages • but does JavaScript “operate another program” • the browser?

7. Other Aspects • verbose vs. terse • PL are typically terse, vs. Applescript • but • but most languages adopted C syntax: C, C++, Java, JavaScript, even Ruby

8. Other Uses of Scripting Languages • CoffeeScript is a better JavaScript • classes: inheritance • consistency • alleviates JavaScript quirks • == and === • is variable defined? • what’s variable’s type • needs to be translated to JavaScript

9. PL Charts • How did PLs develop • typical chart • http://upload.wikimedia.org/wikipedia/commons/a/a7/TaxonomyofProgrammingLanguages.png • mostly C as “grandfather” • Java = C++-- • consider trends (innovation, density) • book publishers, e.g. O’Reilly • http://oreilly.com/news/graphics/prog_lang_poster.pdf

10. Traditional PL Chart (top)

11. Traditional PL Chart (bottom)

12. O’Reilly PLs & Books

13. O’Reilly PLs

14. Most Recent O’Reilly PL Books • 8 out of 13 newer PLs (=60%) • Note: JavaScript ~= ECMA Script ~= ActionScript

15. 215, ICS and PLs Popularity ICS 215 • 5 out of 11 most popular PLs (mpPLs) • 24% of mpPLs ICS • 7 out of 11 mpPLs • 55% of mpPLs

16. Conclusion • The differences between Scripting Languages and Programming Languages are getting more and more blurred • languages are becoming compiled or at least hybrid • languages often operate OS or other applications • e.g. access to file system • our distinction is mainly historical • Java (Pascal) and C++ are taught in intro courses • we need to expose students to other languages • ICS exposes you to most of the trending PLs • already in undergraduate curricullum • in particular in ICS 215 (and ICS 315)

17. Our Definition • now • JavaScript • Ruby • PHP • Python • Perl • in future • other new programming languages as they become important