Euphoria (programming language)

Euphoria is a programming language created by Robert Craig of Rapid Deployment Software in Toronto, Ontario, Canada. Initially developed (though not publicly released) on the Atari ST, the first commercial release was for the 16-bit DOS platform and was proprietary. In 2006, with the release of version 3, Euphoria became open-source software. The openEuphoria Group continues to administer and develop the project. In December 2010, the openEuphoria Group released version 4 of openEuphoria along with a new identity and mascot for the project. OpenEuphoria is currently available for Windows, Linux, macOS and three flavors of *BSD.
Euphoria is a general-purpose high-level imperative-procedural interpreted language. A translator generates C source code and the GNU compiler collection (GCC) and Open Watcom compilers are supported. Alternatively, Euphoria programs may be bound with the interpreter to create stand-alone executables. A number of graphical user interface (GUI) libraries are supported including Win32lib and wrappers for wxWidgets, GTK+ and IUP. Euphoria has a simple built-in database and wrappers for a variety of other databases.
Overview.
The Euphoria language is a general purpose procedural language that focuses on simplicity, legibility, rapid development and performance via several means.
History.
Developed as a personal project to invent a programming language from scratch, Euphoria was created by Robert Craig on an Atari Mega-ST. Many design ideas for the language came from Craig's Master's thesis in computer science at the University of Toronto. Craig's thesis was heavily influenced by the work of John Backus on functional programming (FP) languages.
Craig ported his original Atari implementation to the 16-bit DOS platform and Euphoria was first released, version 1.0, in July 1993 under a proprietary licence. The original Atari implementation is described by Craig as "primitive" and has not been publicly released. Euphoria continued to be developed and released by Craig via his company Rapid Deployment Software (RDS) and website rapideuphoria.com. In October 2006 RDS released version 3 of Euphoria and announced that henceforth Euphoria would be freely distributed under an open-source software licence.
RDS continued to develop Euphoria, culminating with the release of version 3.1.1 in August, 2007. Subsequently, RDS ceased unilateral development of Euphoria and the openEuphoria Group took over ongoing development. The openEuphoria Group released version 4 in December, 2010 along with a new logo and mascot for the openEuphoria project.
Version 3.1.1 remains an important milestone release, being the last version of Euphoria which supports the DOS platform.
Euphoria is an acronym for "End-User Programming with Hierarchical Objects for Robust Interpreted Applications" although there is some suspicion that this is a backronym.
The Euphoria interpreter was originally written in C. With the release of version 2.5 in November 2004 the Euphoria interpreter was split into two parts: a front-end parser, and a back-end interpreter. The front-end is now written in Euphoria (and used with the Euphoria-to-C translator and the Binder). The main back-end and run time library are written in C.
Features.
Euphoria was conceived and developed with the following design goals and features:
Use.
Euphoria is designed to readily facilitate handling of dynamic sets of data of varying types and is particularly useful for string and image processing. Euphoria has been used in artificial intelligence experiments, the study of mathematics, for teaching programming, and to implement fonts involving thousands of characters. A large part of the Euphoria interpreter is written in Euphoria.
Data types.
Euphoria has two basic data types:
Euphoria has two additional data types predefined:
There is no character string data type. Strings are represented by a "sequence" of "integer" values. However, because literal strings are so commonly used in programming, Euphoria interprets double-quote enclosed characters as a sequence of integers. Thus
 "ABC"
is seen as if the coder had written:
which is the same as:
Hello, World!
 puts(1, "Hello, World!\n")
Examples.
Program comments start with a double hyphen codice_1 and go through the end of line.
The following code looks for an old item in a group of items. If found, it removes it by concatenating all the elements before it with all the elements after it. Note that the first element in a sequence has the index one [1] and that $ refers to the length (i.e., total number of elements) of the sequence.
 global function delete_item( object old, sequence group )
 integer pos
 -- Code begins --
 pos = find( old, group )
 if pos > 0 then
 group = group[1 .. pos-1] & group[pos+1 .. $]
 end if
 return group
 end function
The following modification to the above example replaces an old item with a new item. As the variables "old" and "new" have been defined as objects, they could be "atoms" or "sequences". Type checking is not needed as the function will work with any sequence of data of any type and needs no external libraries.
 global function replace_item( object old, object new, sequence group )
 integer pos
 -- Code begins --
 pos = find( old, group )
 if pos > 0 then
 group[pos] = new
 end if
 return group
 end function
Furthermore, no pointers are involved and subscripts are automatically checked. Thus the function cannot access memory out-of-bounds. There is no need to allocate or deallocate memory explicitly and no chance of a memory leak.
The line
 group = group[1 .. pos-1] & group[pos+1 .. $]
shows some of the "sequence" handling facilities. A "sequence" may contain a set of any types, and this can be sliced (to take a subset of the data in a "sequence") and concatenated in expressions with no need for special functions.
Parameter passing.
Arguments to routines are always passed by value; there is no pass-by-reference facility. However, parameters are allowed to be modified "locally" (i.e., within the callee) which is implemented very efficiently as sequences have automatic copy-on-write semantics. In other words, when you pass a sequence to a routine, initially only a reference to it is passed, but at the point the routine modifies this sequence parameter the sequence is copied and the routine updates only a copy of the original.
External links.
Free downloads of Euphoria for the various platforms, packages, Windows IDE, Windows API libraries, a cross-platform GTK3 wrapper for Linux and Windows, graphics libraries (DOS, OpenGL, etc.).