Abstract
This article deals with elementary knowledge of the programming language theory. It is
divided into two parts. There is shown how we can formal prove program by Floyd-Hoare
Logic in the first one. At the beginning is defined a little programming language with basic
commands and further are shown some axioms and rules of Floyd-Hoare Logic. At the end of
the first part is introduced an example of proving simple program. The second part attends to
l-calculus. There is explained its notation and using for representing functions and data
objects as number or list. Further there is shown which classes of functions can be in lcalculus represented.