Ako {
  Program = Stmt*

  // Statement
  Block = "{" Stmt* "}"
  Stmt = (Metadata | If | Assign | AssignTask | TaskDef | SkipTask | Task | ForLoop | Expr | comment)

  Assign = AssignLeft | AssignAdd | AssignIncr | AssignDecr | AssignSub
  AssignTask = Var "=" (SkipTask | Task)
  AssignLeft = Var "=" Expr
  AssignAdd = Var "+=" Expr
  AssignSub = Var "-=" Expr
  AssignIncr = Var "++"
  AssignDecr = Var "--"
  Metadata = "##" id Term

  TaskDef = "task" id (Array)? Block
  SkipTask = "@@" ListOf<id, "."> "(" NamedArguments ")"
  Task = "@" ListOf<id, "."> "(" NamedArguments ")"
  NamedArguments = ListOf<(KeyValue | Expr), ",">
  Arguments = ListOf<Expr, ",">

  // Expression
  Pipe = (Pipe | ExprItem) "|>" ExprItem
  Expr =  Pipe | ExprItem
  ExprItem = LambdaInline | MathExpr

  Term = Fn | bool | Var | Number | String | Array | Dictionary | Last
  Fn = ListOf<id, "."> "(" Arguments ")"
  // Lambda = "(" ListOf<id, ","> ")" "=>" Block
  LambdaInline = "(" ListOf<id, ","> ")" "=>" Expr

  // Math
  MathExpr = BinExpr

  BinExpr = BinExpr "and" EqExpr  -- and
    | BinExpr "or" EqExpr  -- or
    | EqExpr

  EqExpr = EqExpr "==" AddExpr -- eq
    | EqExpr "!=" AddExpr   -- neq
    | EqExpr "<" AddExpr	-- lt
    | EqExpr "<=" AddExpr  -- lte
    | EqExpr ">" AddExpr	-- gt
    | EqExpr ">=" AddExpr  -- gte
    | AddExpr

  AddExpr = AddExpr "+" MulExpr  -- plus
    | AddExpr "-" MulExpr  -- minus
    | MulExpr

  MulExpr = MulExpr "*" PriExpr  -- times
    | MulExpr "/" PriExpr  -- divide
    | MulExpr "%" PriExpr  -- mod
    | PriExpr

  PriExpr = "(" Expr ")"  -- paren
    | "-" PriExpr   -- neg
    | "NOT" PriExpr   -- not
    | Term "++"  -- inc
    | Term "--"  -- dec
    | Term

  // Conditionnal
  If = "if" Expr Block
     ("elif" Expr Block)*
     ("else" Block)?

  // Loop
  ForLoop =  Foreach | While | Infinite | Continue | Return
  Foreach = "for" id ("," id)? "in" Expr Block
  While = "for" Expr Block
  Infinite = "for" Block
  Continue = "continue"
  Return = "return" (Expr)?

  // Identifier / Variable
  Last = "$"
  Var =  Var "[" Expr "]"    -- subscript
              |  Var "[" Expr? ":" Expr? "]"    -- range
              |  Var "." id  -- select
              |  id -- single

  id  = ~(keyword end) char
  char = letter (letter | digit | "_")*
  keyword = "$" | "task" | "for" | "false" | "true" | "or" | "and" | "not" | "if" | "elif" | "else" | "continue" | "return"

  // List
  Array       = "[" ListOf<Expr, ","> "]"
  Dictionary  = "{" ListOf<KeyValue, ","> "}"
  KeyValue = id "=" Expr

  // Boolean
  bool = "true" | "false"

  // String
  String = sqString | dqString | emptyString
  squote = "'"
  sqString = (squote (~squote any)+ squote)
  dquote = "\""
  dqString = (dquote (~dquote any)+ dquote)
  emptyString = "\"\"" | "''"

  // Number
  Number  (a number literal)
    = hex | float | int

  int    = digit+
  float  = digit+ "." digit+
  hex    = "#" hexDigit+

  // Other
  space := "\t" | " " | "\n" | "\r"
  comment = singlecomment | multilinecomment
  singlecomment = "//" (~"\n" any)*
  multilinecomment = "/*" (~"*/"any)* "*/"
}