Stekovaya Tutorial Part1
Stekovaya is a stack based language. It is very light weight but also very versatile.
Let's start with a simple hello world program.
STR Hello World! END MSG
Congratulations! You've made a major step in understanding Stekovaya.
In this simple example, we've added a string (Hello World) and terminated with
END. We've also popped it off of the stack and printed it to the console using
Let's make our example easier to read by adding some comments.
REM is a key word reserved for adding comments.
STR Hello World! END MSG REM Push Hello World! to the stack and pop it off to print to the console.
REM is a hard keyword to memorize for comments, think of it like
REMembering something to write down.
We can also work with numbers. Simply typing numbers will push them to the stack.
1 2 7 3
Booleans are basically true or false. In Stekovaya, a true is a 1 and a false is a 0. We'll review this concept more when we look at comparison operators.
Variables are an easy way to store values. There are two types of variables in Stekovaya: constant and changeable. Both variable types can be declared with
Let's start with a changeable variable. As the name suggests, the values of these variables can be changed.
STR message END STR Hello World END DEF
What are we doing here? First we define an identifier called "message", which is terminated with
END. We assign "message" a value of "Hello World" in a similar fashion, ending it with
DEF. We can use this variable later on like so:
STR message END STR Hello World END DEF message MSG REM we define a "message" variable and then print it to the console.
There are also constant variables. The values of these variables cannot be changed. In order to define a constant variable, simply add an underscore
_ to the beginning of the variable name.
STR _message END STR Hello World END DEF REM the value of _message cannot be changed.
So far, we've reviewed the
MSG command, which prints the top of the stack to the console. We can also print the entire stack to the console using
STK, which can be useful for debugging.
1 2 7 3 STK REM outputs STACK<4> 1 2 7 3 to the console
The other method to print to the console is
DMSG. This method is special in that it does not alter the stack, it simply logs the top of the stack (
MSG logs and pops the top of the stack).
DMSG is used in the exact same way as
1 DMSG REM outputs 1 to the console without popping the stack
Stekovaya does not use the common operators you might expect, as it revolves around a purely stack based programming language. Let's start by learning how to perform simple math.
We can add, subtract, multiply, and divide fairly inuitively using
5 2 ADD MSG
In this example, we simply add the two numbers at the top of the stack and log it to the console. As mentioned earlier, the rest can be done in the same way.
5 2 SUB MSG REM outputs 3 to the console 5 2 MUL MSG REM outputs 10 to the console 5 2 DIV MSG REM outputs 2.5 to the console
We can also calculate other mathematical operations with some useful functions. The first is
POW, which raises the second value of the stack to the first stack power.
2 5 POW MSG REM outputs 32 to the console
We are effectively raising 2 to the 5th power (2 ^ 5). Like
POW, we can also take roots of values using
ROT. This is also the same as taking a value to the 1/n (where n is a real number).
2 4 ROT MSG REM outputs 2 to the console
Here, we take √4, or 4 to the 1/2 power.
In other programming languages, you might expect to see
<=. Stekovaya uses key words to perform similar actions.
5 2 LSS MSG REM equivalent of 5 < 2 REM outputs 0 for false
LSS is used as the less than comparison operator. In order to log the result, we use
MSG. The others are fairly self explanatory, so let's go over them quickly.
5 2 LEQ REM equivalent of 5 <= 2, checks if 5 is less than or equal to 2 5 2 GTR REM equivalent of 5 > 2, checks if 5 is greater than 2 5 2 GEQ REM equivalent of 5 >= 2, checks if 5 is greater than or equal to 2 5 2 EQU REM equivalent of 5 == 2, checks if 5 is equal to 2 5 2 NEQ REM equivalent of 5 != 2, checks if 5 is not equal to 2
Remember, 0 is false and 1 is true. To log the results of comparisons, you can use
There is only one kind of loop in Stekovaya, the
FOR loop. Initializing a loop is easy. Simple start a loop with
FOR and end it with
EFOR For instance, the example below infinitely logs "Hello World!" to the stack.
FOR STR Hello World! END MSG EFOR
In order to terminate or break from a loop, you must use
While it seems like useless filler, you can also choose not to do anything with the stack.
EMP REM nothing happens
You can exit a Stekovaya program with either
EXT exits the program with a status of 0, where as
ERX exits with a status of 1.
EXT REM exit status 0 ERX REM technically this won't run, but if it did it would exit with status 1.
Thanks @AdCharity for write markdown!