Why scripting language is required?

Answer 1

Everything that an electronic digital computer does is determined by sequences of instructions, which are stored in the form of binary values. Instructions in that form are called machine language. Machine language is extremely tedious and difficult for humans to read, write or understand. To make it easier for humans to write instructions for computers, all sorts of languages have been developed, which can all be automatically translated into machine language. Over many decades, new programming languages have been designed to help people think about programs in more abstract ways, avoid making mistakes, and write programs in parts or layers that can be used by other programmers. The objective of almost all programming languages is to make people more productive when developing and maintaining computer programs.

Answer 2

We use programming languages to create machine code. Machine code is the native language of the machine and is written entirely in binary. While it is possible to create machine code by hand it is extremely difficult, laborious and prone to error. Thus machine code is limited to writing relatively trivial programs. One such program is called an assembler which translates a low-level symbolic language known as assembly language into machine code. Assembly language maps one-to-one with the instruction set of the computer and is therefore very simple to translate. However, different machine types have different instructions sets, thus each machine type requires its own assembler and thus its own assembly language. As a result, assembly languages are machine-dependant languages.

In order to write code that is portable between machine types we need to use high-level symbolic languages. These languages are more abstract and much easier for humans to work with. To convert these languages to machine code we need to use another type of translator known as a compiler. These are more complex than assemblers but they do pretty much the same job. As with assemblers, each machine type has its own compiler. However, because high-level source code is more abstract than assembly language it need not be machine-dependent. Thus the same source code may be compiled upon any machine with a suitable compiler.

Some high-level languages use interpretation rather than compilation. Interpreters do not translate the entire source code at once as compilers and assemblers do, they translate one statement at a time. The main advantage of interpretation is that you can more quickly develop the software because there is no need to wait for the program to compile in order to execute it; you can execute immediately. With compiled languages, every time you change the source code you must recompile, but with interpreted languages you can pause execution, edit the code and then continue execution with the modified code. While paused, you can also invoke commands to modify the machine's state. This is extremely useful when testing new algorithms.

Some languages are both compiled and interpreted. Java is a typical example. First, the program must be compiled but rather than creating machine code this creates byte code. The byte code is then interpreted. The main advantage of this is that the byte code is portable (non-machine-dependent) and is easier to interpret than the non-compiled source code would be. in other words, the source need only be compiled once but can be executed upon any machine with a suitable interpreter.

With these programming languages it would still be possible to write computer programs in machine code, but these languages exist to make life easier for the programmer. This makes it possible to produce more complex programs much more quickly and with fewer errors than would be possible with machine code alone.

Answer 3

For pre-compiled in at least some sense for superior performance.