ExpL is a simple programming language designed specifically for instructional purposes. Application programs for eXpOS may be written in ExpL.
The ExpL compiler supplied along with the eXpOS pakage extents the language with an additional eXpOS library interface function exposcall(). ExpL programs can invoke eXpOS system calls and dynamic memory allocation routines supported by the library by passing appropriate arguments to the exposcall() function. The exposcall() interface is given in detail here.