Introduction

Teeton is a simple programming language created for Runtime Systems course at the Faculty of Information Technology at the Czech Technical University.

Installation

Once you have copy of this repository, you can run make build to build teeton executable. Then it is a good idea to run make test to ensure that everything works correctly.

If everything is fine you can use make run to open teeton console. By running make install the teeton executable is copied into /usr/local/bin and can be used directly in terminal. If you want to get rid of it, simply run make uninstall.

Usage

You can use teeton either in console mode or to run teeton programs.

Console mode

Console mode can be used by running teeton executable without any arguments.

$ teeton
TEETON console 
use ctrl + C to exit
T> 1 + 2

3

Every statement is evaluated after 2 newlines.

Running programs

Once you have written your program, you can run it with teeton. Simply give teeton executable program path as an argument.

$ teeton my_program.ttn

You can see some programs in examples folder.

Language

Types

Teeton supports 4 types.

Int

Int represents positive and negative whole numbers. Teeton does not support real numbers.

x = 10
y = -5

Char

Char represents single character. Must be enclosed in single quotes.

a = 'a'

Bool

Represents boolean value. Two keywords - True and False are used.

a = True
b = False

Lists

Lists can consist of other types. There are functions for manipulating the lists (see below). You can create empty list using []:

my_list = []

Strings are represented as a list of chars. You can create a list of chars using double quotes.

my_list_of_chars = "Hello Teeton!"

Variables

Variables are defined with variable name and expression that will be reduced to a value.

<variable name> = <expression>

Same name can be used to redefine the variable. You can even change type.

x = 1
x = 'a'

Operators

Teeton has various arithmetic, comparison and logical operators. Here is a table of available operators and types that can be used with them.

+   : (int int) -> int, (list list) -> list
-   : (int int) -> int
*   : (int int) -> int
/   : (int int) -> int
<   : (int int) -> bool, (char char) -> bool, (list list) -> bool
>   : (int int) -> bool, (char char) -> bool, (list list) -> bool
<=  : (int int) -> bool, (char char) -> bool, (list list) -> bool
>=  : (int int) -> bool, (char char) -> bool, (list list) -> bool
==  : (int int) -> bool, (char char) -> bool, (list list) -> bool, (bool bool) -> bool
!=  : (int int) -> bool, (char char) -> bool, (list list) -> bool, (bool bool) -> bool 
!   : (bool) -> bool
&&  : (bool bool) -> bool
||  : (bool bool) -> bool
=== : (any any) -> bool

Remember that you can't mix types for binary operators with only exception for === which is reference comparison.

All binary operators are used with infix notation.

x = 1 + 2
y = x > 3

Lists

There are several functions for manipulating lists.

append : (list any) -> void
get    : (list int) -> any
set    : (list int any) -> void
len    : (list) -> int

append

Appends an element at the end of the list.

xs = []
append(xs 2)
append(xs (2 + 8 * 2))

get

Return the element at the given index.

word = "hello"
get(word 1) # -> 'e'

set

Set an element at the given index to a new value.

word = "hello"
set(word 1 'x') # word now contains "hxllo"

len

Return the length of a list.

word = "hello"
len(word) # -> 5

If Else block

You can use if else block in Teeton as follows:

if (x < 10) {
    # do something
} else {
    # do something else
}

The expression used in if condition must resolve in Bool type. Else branch is compulsory.

Loops

Teeton supports only while loop:

i = 0
while (i < 10) {
    # do something
    i = i + 1
}

Loop can be stopped using break statement.

i = 0
while (True) {
    if (i > 10) {
        break
    } else {
        i = i + 1
    }
}

User Input

Teeton has few statements to read user input.

scan_int

Scan int from user input.

a = scan_int

# You can use it in any expression
if (scan_int < 10) {
    # ...    
} else {
    # ...
}

scan_char

Scan single character from user input.

a = scan_char

scan_string

Scan list of characters from user input.

str = scan_string

Output

Teeton has print and println functions that print to standard output.

# print with the final newline
println("Hello Teeton!")

# or without the final newline
x = 2
print("The number is: ")
print(x)

Comments

The hash character # is used for commends. Basically everything from # to the end of line is comment.

Examples

You can find some examples in examples folder.

• hello.ttn - Simple hello world
• reverse_string.ttn - Example of reading string from user input and reversing it
• is_palindrome.ttn - Program that detects whether the given string is palindrome
• bubble_sort.ttn - Example of bubble sort algorithm in teeton