dash-lang 0.1.0

A simple interpreted language
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WHITESPACE     = _{ " " | "\t" | "\n" }

program        =  { SOI ~ statement* ~ EOI }

statement      =  {
    print_stmt
  | let_stmt
  | if_stmt
  | while_stmt
  | break_stmt
  | continue_stmt
  | return_stmt
  | fn_stmt
  | call_stmt
}

print_stmt     =  { "print" ~ "(" ~ expr ~ ")" }
let_stmt       =  { "let" ~ ident ~ "=" ~ expr }
if_stmt        =  { "if" ~ expr ~ block ~ ("else" ~ block)? }
while_stmt     =  { "while" ~ expr ~ block }
break_stmt     =  { "break" }
continue_stmt  =  { "continue" }
return_stmt    =  { "return" ~ expr }
fn_stmt        =  { "fn" ~ ident ~ "(" ~ param_list? ~ ")" ~ block }
call_stmt      =  { call_expr }

param_list     =  { ident ~ ("," ~ ident)* }
arg_list       =  { expr ~ ("," ~ expr)* }

block          =  { "{" ~ statement* ~ "}" }

expr           =  { term ~ (add_op ~ term)* }
term           =  { factor ~ (mul_op ~ factor)* }
factor         =  { comparison }
comparison     =  { primary ~ (comparison_op ~ primary)? }
primary        =  {
    number
  | string
  | call_expr
  | ident
  | "(" ~ expr ~ ")"
}

call_expr      =  { ident ~ "(" ~ arg_list? ~ ")" }

ident          = @{ ASCII_ALPHANUMERIC+ }
number         = @{ "-"? ~ ASCII_DIGIT+ }
string         = @{ "\"" ~ (!"\"" ~ ANY)* ~ "\"" }

add_op         =  { "+" | "-" }
mul_op         =  { "*" | "/" }
comparison_op  =  { ">" | "<" | ">=" | "<=" | "==" | "!=" }