Scripting Languages (was Re: Techniques for writing an interpreter)

Chris Reedy
>A quick question: What are the key differences between a scripting
>language and an ordinary programming language? That is, what is it
>about a language that makes it better or worse for the uses described
>above?


Here's some features of languages (at least on Unix)
described as scripting that I think have in common.


Useful features.
================


Built-in support for hash tables, lists and regular expressions. Often
  with syntax support.


Garbage collection. Consequent greater flexibility of creating and
  disposing small objects, especially strings.


OS support provided simply - files, directories, fork, exec,
  file handles and IPC (pipes and sockets)


Extension to native C code is often done simply


Byte code generated on fly or interpreted language. Aides portability,
  'feedback' style development.


I don't like these aspects
==========================


Type checking is often minimal, often only done at runtime. I suppose
    this feature is so you don't have to do extra typing for declarations


Often special characters are used to denote variable usage / type. These
    are a pain, and often quoting special characters can be a problem.


The start-up time can be large, depending on script size and functionality
    provided by the package.


Trends in scripting languages
=============================


Module and name space support. Attempt to provide some sort of
object-orientatedness


GUI interface.


Java considered a scripting language?
=====================================


I would guess three things stop Java being considered a scripting language
in the same sense and Perl, Python and TCL:


type checking


OS support is only done through the Java Way - for example no forking,
just threads.


C native code is not simple (although maybe with SWIG?)


Jamie Honan
jhonan@mpx.com.au
--

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