Chap

Chap is an easy to learn, dynamic, interpretive, and keyword-less language written in Rust.

Remember, Chap is not a tool! its Art.

Syntax is something between Lisp, Assembly and PHP.

ChapApp is an offline Chap Editor/Compiler on Browser (Powered by WASM). ChapApp is written in Rust(Dioxus) as well. Open ChapApp in a new tab.

Table of content

1. Why was it named 'Chap'?
2. Features
3. Keywords
4. Syntax
5. Operators
6. ControlFlow
7. Samples
8. Data Types
9. Memory Management
10. Installation
11. How to use
12. Builtin function

Name

Rust or راست in persian means right and Chap or چپ means left.

If you code in rust(right) too much, you gradually become capitalist after a while. So you need to write some chap(left) to escape from the matrix.

Chap unlocks Two-Dimensional Full Stack Development. Front⬆️End, Back⬇️End, Rust➡️End, Chap⬅️End.

Features

1. Easy to learn.
2. Cross platform (It runs on Linux, MacOS, Windows, Web(WASM))

Keywords

What makes a programming language hard to learn?

"Keywords"

There are no keywords in Chap.

Syntax

A normal line of code in chap has 3 chunks separated with -> operator:

chunk1 -> chunk2 -> chunk3

param1, param2 -> function_name -> $output_variable

For example:

1, 2 -> add -> $sum

1 and 2 separated by "," are input params.
These input params are moving to "add" function.
Finally $sum is a variable that holds the add result in it.

Note: "add" is not a keyword, it's a builtin function.

Ok but why?

English language is a "left to right" (aka LTR) language, and programming languages should follow the same rule, right?

Wrong:

// c base languages:
result = send(sqrt(1 + 2).toString());
   ↑       ↑    ↑     ↑       ↑
   5       4    2     1       3

But chap:

// chap
1,2 -> add -> sqrt -> to_string -> send -> $result
        ↑       ↑         ↑          ↑        ↑
        1       2         3          4        5

This is actually left to right like normal english.

Note: "Chain" syntax is added in version 2.0.0

Syntax Rules

Make a comment with // and anything you write on the right side will be ignored by compiler.

1, 2 -> add -> $sum // this is a comment

You can write many lines of code in one line by separating lines by ";"

1 -> $a; $a, 2-> sum -> $b; $b -> print -> $_

Input params are separated by comma character ",".

Input params can be:

1. Variable
2. String with " character around like: "hello world"
3. Int just a number: 5
4. Float just a normal form of floating point number 3.14
5. Bool is a boolean value which is a true or false
6. Tags start with @. (more on control flow)

$a, "hello", 5, 3.14, false -> function_name -> $output_var

Function names are not case-sensitive.

Function names are not sensitive about anything else:

// to_string = ToString = TOSTRING = to string = t o s t r_i_n_g

Variables should start with $ which is known as the most loved feature of PHP.

Variable name rules:

$12 // Ok
$sp a ce // OK
$#^3 // Ok
$a,b // comma not allowed
$really? // question mark at the end not allowed
$rea?lly // OK
$some->thing // "->" is not allowed 

Short syntax features

If a function has no output variable you can remove chunk3:

"hello world" -> print
    ↑              ↑         ↑
   input         function   removed chunk3

If a function has no input param you can remove chunk1:

              input -> $user_input
 ↑              ↑         ↑
nothing      function    output

Removing chunk2 (function name) means assigning a variable:

1 -> $variable
// it's actually short for:
// 1 -> assign -> $variable

If a function has no input param and output_var you just write function name:

exit

If a function has output var but you removed chunk3 the result of function will get printed:

1, 2 -> add
// it's short for:
// 1, 2 -> add -> print

If you just write some params. chap will print them:

1, 2
// result: 1, 2

// or
$a
// prints whatever $a is

As you can guess, we have the world's smallest hello world:

"Hello World"

I wish I could remove double quotes too :)

Chain syntax (aka pipe)

Sometimes you have a collection of function calls like this:

1, 2 -> add -> $tmp1
$tmp1 -> sqrt -> $tmp2
$tmp2 -> print

As you can see, output of a function call is input of the next function call.

In this case, you can use piping syntax to write functions next to each other and get rid of temp variables:

1, 2 -> add -> sqrt -> print

Parentheses

You can't use Piping when one of the functions has more than one param.

1,2 -> add -> add -> print
               ↑
               This needs two input params

In this case you can use Parentheses:

(1,2 -> add), (3 -> sqrt) -> add -> print

This converts two:

1,2 -> add -> $TMP1
3 -> sqrt -> $TMP2
$TMP1, $TMP2 -> add -> print

Operators

There is one operator -> which moves data from left to right and it is language logo.

Why are operators bad?
Because they behave different with different types. Look at this python example:

number = input("Enter a number:")
result = number * 5 # multiply number by 5
print(number, "* 5 =", result)

Following code has a bug and the result will be:

Enter a number: 3
3 * 5 = 33333
# no runtime error

Why? Because Python uses the same operator for math.multiply and strings.repeat.

So * operator "IS NOT A TYPE SAFE" operator and it will "DO UNEXPECTED THINGS" when your forget to pass the right type to it and it will happen without throwing runtime errors (which is bad).

Same code in Chap:

input -> $number
$number, 5 -> multiply -> $result 
$result
// error in line 2: multiply function works only with numbers int and float

Runtime errors are much better than logical errors, and in chap we have the repeat function:

"foo ", 3 -> repeat
// foo foo foo 

In many languages "+" operator has the same problem:

# Python
def add(a, b):
    a + b # concat or add? both?

add("1", "2") # 12
add(1, 2) # 3

// Chap:
"1", "2" -> concat // 12
1, 2 -> concat // 12 // you can concat integers safely
1, 2 -> add // 3
"1", "2" -> add // runtime error

Debugger

You can put a ? at the end of function name to debug that line:

1 -> $a
2 -> $b
$a, $b -> add? -> $c
// result 1, 2 -> add -> 3

Chap also has a function called "dump" which prints every variable you have.

Control Flow

You can create a tag like this:

@tag_name

And you can jump to it:

@tag_name -> jump
// or
@tag_name, true -> jump_if
// or
@tag_name, 1, 1 -> jump_if_equal
// or
@tag_name, 1, 0 -> jump_if_not_equal

loop

Jumping backward makes loops:

@l
    "Hello until your battery dies"
@l -> jump

if

@i, 1, 1 -> jump_if_equal
    "this will not print"
@i

Note: Indention is not necessary

Array

Initialize:

[1 2 3 4] -> $myArray

Insert:

$myArray, 5 -> insert

Pop:

$myArray-> pop -> $last_item

Get item by index:

$myArray, 1 -> get -> $first_item
// arrays index start from 1

Samples

Note: You can test and tweak samples at ChapApp.

hello_world.chp

"Hello world"

Hello world

counter.chp

0 -> $counter
@l
    $counter -> increase
@l, $counter, 100 -> jump_if_not_equal
$counter

100

number_guess_game.chp

1,10 -> random_number -> $answer
@loop
    input -> $guess
    $guess -> to_int -> $guess
    @win, $answer, $guess -> jump_if_equal
    "wrong"
@loop -> jump

@win
"you win"

1
wrong
2
wrong
3
you win

christmas_tree.chp

 // Editable
0 -> $counter
@loop
    $counter -> increase

    $counter, 2 -> multiply -> $stars_size
    10, $counter -> minus -> $space_size

    "*", $stars_size -> repeat -> $stars
    " ", $space_size -> repeat -> $spaces

    $spaces, $stars -> cat
@loop, $counter, 10 -> jump if not equal

         **
        ****
       ******
      ********
     **********
    ************
   **************
  ****************
 ******************
********************

christmas_tree_with_trunk.chp

 // Editable
0 -> $counter
@loop
    $counter -> increase

    $counter, 1 -> multiply -> $stars_size
    19, $counter -> minus -> $space_size

    " * ", $stars_size -> repeat -> $stars
    " ", $space_size -> repeat -> $spaces

    $spaces, $stars -> cat

    "`*-", $stars_size -> repeat -> $stars
    " ", $space_size -> repeat -> $spaces

    $spaces, $stars -> cat
@loop, $counter, 10 -> jump if not equal

3 -> $c
@loop
    $c-> increase

    $c, 2 -> multiply -> $stars_size
    22, $c-> minus -> $space_size


    "*", $stars_size -> repeat -> $stars
    " ", $space_size -> repeat -> $spaces

    $spaces, $stars -> cat

@loop, $c, 7 -> jump if not equal

                   * 
                  `*-
                  *  * 
                 `*-`*-
                 *  *  * 
                `*-`*-`*-
                *  *  *  * 
               `*-`*-`*-`*-
               *  *  *  *  * 
              `*-`*-`*-`*-`*-
              *  *  *  *  *  * 
             `*-`*-`*-`*-`*-`*-
             *  *  *  *  *  *  * 
            `*-`*-`*-`*-`*-`*-`*-
            *  *  *  *  *  *  *  * 
           `*-`*-`*-`*-`*-`*-`*-`*-
           *  *  *  *  *  *  *  *  * 
          `*-`*-`*-`*-`*-`*-`*-`*-`*-
          *  *  *  *  *  *  *  *  *  * 
         `*-`*-`*-`*-`*-`*-`*-`*-`*-`*-
                  ********
                 **********
                ************
               **************

DataTypes

1 -> type_of
int

3.14 -> type of
float

"ali" -> TypeOf
string

true -> type      
boolean

-> [1 2 3] -> type      
list

Memory Management

Your OS will free memory after process is done!

Installation

Download release

link

Build from source

git clone https://github.com/ali77gh/Chap
cargo build --release
sudo cp ./target/release/chap /usr/bin

How To Use

REPL (Run Execute Print Loop)

./repl/mod.rs

❯ chap
-> "hello world"
hello world
-> 

File_executor

./file_executor/mod.rs

❯ chap number_guess_game.chp 
1
wrong
2
wrong
3
you win answer was: 3

Use As lib

./lib.rs

cargo add chap # this include eval function

or

cargo build --release --lib

Release Note version 2.0.0

• Arrays
• fix: 'random' module will not work on WASM
• eval function
• ChapApp
• Piping syntax (1, 2 -> add -> toString -> print)
• Parentheses (1, 2 -> add), (2, 3 -> add) -> concat -> $var // 35
• New debugger syntax 1,2 -> add? -> $sum

Stars

Builtin Functions

runtime/builtin_function
Chap has 49 builtin function(version 2.0.0) (less than Java's keywords)