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mxsjoberg / hlwasm

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hlwasm

A High-Level WebAssembly programming language.

grammar

<program> ::= <function> | <program> <function>

<function> ::= <function_declaration> <block>

<function_declaration> ::= 'function' <identifier> '(' <parameters> ')' ':' <return_type>

<parameters> ::= <parameter> | <parameter> ',' <parameters>

<parameter> ::= <identifier> ':' <type>

<return_type> ::= <type> | 'void'

<block> ::= '{' <statement>* '}'

<statement> ::= <assignment> | <expression> | <return> | <if_statement> | <while_statement> | <block>

<assignment> ::= <identifier> '=' <expression>

<expression> ::= <binary_operation> | <unary_operation> | <literal> | <identifier> | <function_call>

<binary_operation> ::= <expression> <binary_operator> <expression>

<unary_operation> ::= <unary_operator> <expression>

<literal> ::= <integer> | <float> | <boolean> | <string>

<if_statement> ::= 'if' <expression> <block> ('else' <block>)?

<while_statement> ::= 'while' <expression> <block>

<binary_operator> ::= '+' | '-' | '*' | '/' | '%' | '==' | '!=' | '<' | '>' | '<=' | '>=' | '&&' | '||'

<unary_operator> ::= '-' | '!' 

<function_call> ::= <identifier> '(' <arguments> ')'

<arguments> ::= <expression> | <expression> ',' <arguments>

<type> ::= 'int' | 'float' | 'bool' | 'string' | <identifier>

<identifier> ::= <letter> <alphanumeric>*

<integer> ::= <digit>+

<float> ::= <digit>+ '.' <digit>*

<boolean> ::= 'true' | 'false'

<string> ::= '"' <any_character>* '"'

<letter> ::= 'a' | 'b' | ... | 'z' | 'A' | 'B' | ... | 'Z'

<digit> ::= '0' | '1' | ... | '9'

<alphanumeric> ::= <letter> | <digit>

example hlwasm program

function factorial(n: int): int {
  if (n == 0) {
    return 1;
  } else {
    return n * factorial(n - 1);
  }
}

function main() {
  let input: int = 5;
  let result: int = factorial(input);
  print("Factorial of " + input + " is " + result);
}

example wat (to be translated from hlwasm program)

(module
  (func $factorial (param $n i32) (result i32)
    (if (result i32)
      (i32.eqz (get_local $n))
      (then (i32.const 1))
      (else
        (i32.mul (get_local $n)
                 (call $factorial (i32.sub (get_local $n) (i32.const 1))))
      )
    )
  )
  (func $main
    (local $input i32)
    (local $result i32)
    (set_local $input (i32.const 5))
    (set_local $result (call $factorial (get_local $input)))
    (call $print
      (call $concat
        (call $concat
          (call $concat (i32.const 12) (i32.const 70))
          (i32.const 97)
        )
        (call $concat (i32.const 99) (call $concat (i32.const 116) (i32.const 111)))
      )
    )
  )
  (func $print (param $strptr i32))
  (func $concat (param $strptr1 i32) (param $strptr2 i32) (result i32))
  (export "factorial" (func $factorial))
  (export "main" (func $main))
  (export "print" (func $print))
  (export "concat" (func $concat))
)

utility functions: print and concat

(func $print (param $strptr i32)
  (call $puts (get_local $strptr))
)

(func $concat (param $strptr1 i32) (param $strptr2 i32) (result i32)
  (local $len1 i32)
  (local $len2 i32)
  (local $result i32)
  (local $i i32)

  ;; Get length of first string
  (set_local $len1 (call $strlen (get_local $strptr1)))

  ;; Get length of second string
  (set_local $len2 (call $strlen (get_local $strptr2)))

  ;; Allocate memory for result string
  (set_local $result (call $malloc (i32.add (get_local $len1) (get_local $len2))))

  ;; Copy first string into result string
  (block
    (set_local $i (i32.const 0))
    (loop
      (br_if $concat_end (i32.ge_u (get_local $i) (get_local $len1)))
      (i32.store8
        (i32.add (get_local $result) (get_local $i))
        (i32.load8_u (i32.add (get_local $strptr1) (get_local $i)))
      )
      (set_local $i (i32.add (get_local $i) (i32.const 1)))
      (br $concat_loop)
    )
  )

  ;; Copy second string into result string
  (block $concat_loop
    (set_local $i (i32.const 0))
    (loop
      (br_if $concat_end (i32.ge_u (get_local $i) (get_local $len2)))
      (i32.store8
        (i32.add (get_local $result) (i32.add (get_local $len1) (get_local $i)))
        (i32.load8_u (i32.add (get_local $strptr2) (get_local $i)))
      )
      (set_local $i (i32.add (get_local $i) (i32.const 1)))
      (br $concat_loop)
    )
  )

  ;; Null-terminate the result string
  (i32.store8 (i32.add (get_local $result) (i32.add (get_local $len1) (get_local $len2))) (i32.const 0))

  ;; Return pointer to result string
  (get_local $result)

  (block $concat_end)
)

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