zayfen / RivenLang

a language implemented in rust

RivenLang

A simple language for children implemented in rust. We can teach children basic math knowledge and basic coding knowledge in RivenLang.

Why RivenLang? Because my cute daughter named "芮文" in Chinese, its pronunciation very like the word riven in English. So, as a matter of course, I named this programming language riven.

Example

fib.riven

// Code example

program {
    fn fib(n) {
      if (n = 0) {
        return 0;
      }

      if (n = 1) {
        return 1;
      }

      fib_n = fib(n-1) + fib(n-2);
      printf("fib(%d): %d\n", n, fib_n);
      return fib_n;
    }

    fn main() {
      fib((1+1) * 2);
      return 0;
    }
  }

Output:

❯ ./b.out
fib(2): 1
fib(3): 2
fib(2): 1
fib(4): 3

How to compile? riven <your source file path>, e.g.: riven fib.riven

If build successfully, there is a file named b.out in the directory source file stays, Now, we can run b.out in terminal just like the way your run ls cd.

grammar

<program>   ::= program { <statement-list> }

<statement-list>    ::= <empty>
                        | <statement> <statement-list>

<statement>   ::=   <assign-statement>
                    | <call-statement>
                    | <return-statement>
                    | <function-statement>
                    | <if-statement>

<function-statement>  ::= fn <identifier> ( <identifier-list> ) { <statement-list> }

<if-statement>  ::= if (<logic-expression>) { <statement-list> }

<return-statement>  ::= return <expression> ;

<assign-statement>     ::= <identifier> = <expression> ;

<call-statement>    ::= <call-expression> ;

<logic-expression> ::= <compare-expression>
                    |  not (<logic-expression>)
                    |  and (<logic-expression> , <logic-expression>)
                    |  or (<logic-expression> , <logic-expression>)



<compare-expression>   ::= <expression>
                      | <expression> = <expression>
                      | <expression> > <expression>
                      | <expression> < <expression>  

<expression-list>   ::= <expression>
                      | <expresison> , <expression-list>

// identifier (  <=> identifier [*/+-]
<expression>    ::= <component-arithmetic-expression>


<call-expression>       ::= <identifier> ()
                          | <identifier> ( <expression-list> )

<component-arithmetic-expression> ::= <component-term>
                                    | <component-term> + <component-arithmetic-expression>
                                    | <component-term> - <component-arithmetic-expression>

<compoennt-term>  ::= <component-factor>
                    | <component-factor> * <component-term>
                    | <component-factor> / <component-term>

// like factor
<component-factor>  ::= <arithmetic-expression>
                      | ( <component-factor> ) 

<arithmetic-expression> ::= <term>
                        | <term> + <arithmetic-expression>
                        | <term> - <arithmetic-expression>

<term>      ::= <factor>
            | <factor> * <term>
            | <factor> / <term>

<factor>    ::= <primary> | <identifier> | <call-expression>

<primary>   ::= <string> | <number>

<identifier-list>       ::= <identifier>
                        | <identifier> , <identifier-list>

// useName
<identifier>    ::= [a-z][A-Z]

<string>    ::= '<charactoers>'
            | ''
<characters>    ::= <character>
                | <character> <characters>


<number>    ::= <integer>
<integer>   ::= <decimal digit>
            | <decimal digit> <integer>
<decimal digit>     ::= 0|1|2|3|4|5|6|7|8|9