DataMelt is written in Java, but can be used with the Python language too. Thus it combines the word's most-popular enterprise language, Java, with the most popular scripting language used in data science.
Java is far and away the most popular and widely used programming language in the world. It is enterprise standard language. It has been the number 1 most popular language since its creation in the mid-90's. See TIOBE popularity Index.
DataMelt uses scripting languages which are significantly faster than the standard Python implemented in C. For example, DataMelt provides Groovy dynamic scripting language which is a factor 10 faster than the standard Python for numeric calculations. JRuby is another dynamic language included in DataMelt which has a higher performance compared to Python. DataMelt algorithms implemented in Java are as fast as similar programs in C/C++.