For a long time Ada has been a popular programming language aimed at objects (a bit like C++, although it also has certain properties of Pascal in its syntax). This GNAT - Ada compiler is nothing more than a source code compiler written in Ada 95.
The best thing about GNAT - Ada compiler is that the syntax is highly legible, and it is also highly portable, stable and, above all, hardly consumes resources. That makes Ada ideal for programmers in PCs that aren`t very powerful.
GNAT - Ada compiler is distributed freely as a GNU licence.