And

The And programming language is a very peculiar esoteric language by User:Rdococ.

Structure
And takes advantage of lazy evaluation so that you can do this:

In that snippet of And code, if x 2 or the fourth entry of z = 1, and your input is the letter a, then x will become y + 1 and y will become 0, and then the user will see the words, "Hello guys!", and then the instruction pointer will return to the top, asking for another input. The reason this stuff happens is because of lazy evaluation - which allows a chain of and operators like that to work like a conditional.

And code is essentially lines upon lines of chained && and || operations that are repeatedly evaluated over and over again, asking the user for input every time. Who needs conditionals?!

Oh and a few more things. The exit statement - when evaluated - will end the program. The print statement - when evaluated - will print a message. And stuff like assignment and printing always return true.

Computational Class
At least that of a push down automaton.

Proof
This code halts when the number of {'s inputted equals the number of }'s inputted - that is, the brackets are nested properly.

Reduction to brainfuck
ugh... I know it is possible... but...

Cat program
This is a bit restricted because the user can only input one character at a time.

99 bottles of beer
This version adds a new line every time it is evaluated. It goes from 99 to 0 and then repeats, and it handles grammar correctly.