pub(all) suberror InterpreterError {
  TypeMismatch(String, String)
  KeyNotFound(String)
  IndexOutOfBounds(Int)
  InvalidOperation(String)
  DivisionByZero
  TypeError(String)
  EvalError(String)
}

pub(all) enum BinaryOp {
  Add
  Subtract
  Multiply
  Divide
  Modulo
  Equal
  NotEqual
  LessThan
  LessEq
  GreaterThan
  GreaterEq
  And
  Or
}

pub(all) enum Expr {
  Identity
  Literal(Literal)
  Pipe(Expr, Expr)
  Comma(Expr, Expr)
  Key(String)
  Index(Array[Int])
  Slice(Int?, Int?)
  Optional(Expr)
  ArrayConstruct(Expr?)
  ObjectConstruct(Array[(Expr, Expr?)])
  Operation(Expr, BinaryOp, Expr)
  Length
  Keys
  Values
  Type
  Empty
  Not
  Map(Expr)
  Select(Expr)
  Sort
  SortBy(Expr)
  Reverse
  Flatten(Int?)
  Unique
  UniqueBy(Expr)
  GroupBy(Expr)
  Combinations
  Transpose
  Add
  Floor
  Sqrt
  Min
  MinBy(Expr)
  Max
  MaxBy(Expr)
  Round
  Ceil
  Abs
  Split(String)
  Join(String)
  StartsWith(String)
  EndsWith(String)
  Contains(Expr)
  Inside(Expr)
  Has(String)
  In(Expr)
  ToEntries
  FromEntries
  WithEntries(Expr)
  MapValues(Expr)
  Range(Int)
  RangeFromTo(Expr, Expr)
  RangeWithStep(Expr, Expr, Expr)
  First
  FirstGen(Expr)
  Last
  LastGen(Expr)
  Repeat(Expr)
  IndicesOf(Expr)
  IndexOf(Expr)
  Any
  AnyGen(Expr, Expr)
  All
  AllGen(Expr, Expr)
  IfThenElse(Expr, Expr, Expr)
  TryCatch(Expr, Expr?)
  Variable(String)
  As(Expr, String, Expr)
  Reduce(Expr, String, Expr, Expr)
  Foreach(Expr, String, Expr, Expr, Expr?)
  Recurse
  RecurseWith(Expr, Expr)
  Walk(Expr)
  Path(Expr)
  Update(Expr, Expr)
  Assign(Expr, Expr)
  Alternative(Expr, Expr)
  AddAssign(Expr, Expr)
  SubAssign(Expr, Expr)
  MulAssign(Expr, Expr)
  DivAssign(Expr, Expr)
  ModAssign(Expr, Expr)
  AltAssign(Expr, Expr)
  Format(String)
  StringInterpolation(Array[(String, Expr?)])
  FunctionDef(String, Array[String], Expr)
  FunctionCall(String, Array[Expr])
  LTrimStr(String)
  RTrimStr(String)
  AsciiUpcase
  AsciiDowncase
  Explode
  Implode
  ToJsonString
  FromJsonString
  Nth(Int)
  RIndex(Expr)
  Paths
  PathsWithFilter(Expr)
  LeafPaths
  GetPath(Expr)
  SetPath(Expr, Expr)
  DelPaths(Expr)
  Limit(Int, Expr)
  Until(Expr, Expr)
  While(Expr, Expr)
  Pow(Expr)
  Log
  Exp
  Sin
  Cos
  Tan
  Asin
  Acos
  Atan
  Test(String)
  Match(String)
  Capture(String)
  Scan(String)
  Splits(String)
  Sub(String, String)
  GSub(String, String)
}

pub(all) enum Literal {
  Null
  Bool(Bool)
  Number(Double)
  String(String)
}

fn eval(expr : Expr, input : Json) -> Iterator[Json] raise