type binop =
  | Add
  | Sub
  | Mul
  | Div
  | Eq
  | Ne
  | Lt
  | Le
  | Gt
  | Ge
  | And
  | Or

type expr = {
  e : expr_desc;
  espan : Location.span;
}

and expr_desc =
  | EInt of int
  | EBool of bool
  | EString of string
  | EUnit
  | EVar of string
  | ELet of string * expr * expr
  | ELambda of string * expr
  | EApp of expr * expr
  | EIf of expr * expr * expr
  | EBinop of binop * expr * expr
  | ENeg of expr
  | ETuple of expr list
  | ERecord of (string * expr) list
  | EField of expr * string
  | EFilter of expr
  | EMap of expr
  | ESum
  | ECount

type tyexpr = {
  ty : tyexpr_desc;
  tyspan : Location.span;
}

and tyexpr_desc =
  | TyName of string
  | TyCollection of tyexpr
  | TyTuple of tyexpr list

type record_decl = {
  rd_name : string;
  rd_name_span : Location.span;
  rd_fields : (string * tyexpr) list;
  rd_span : Location.span;
}

type input_decl = {
  in_name : string;
  in_name_span : Location.span;
  in_ty : tyexpr;
  in_span : Location.span;
}

type helper = {
  h_name : string;
  h_name_span : Location.span;
  h_params : string list;
  h_body : expr;
  h_span : Location.span;
}

type query = {
  q_name : string;
  q_name_span : Location.span;
  q_body : expr;
  q_span : Location.span;
}

type declaration =
  | DRecord of record_decl
  | DInput of input_decl
  | DHelper of helper
  | DQuery of query

type program = {
  prog_records : record_decl list;
  prog_input : input_decl;
  prog_helpers : helper list;
  prog_query : query;
}

let make e espan = { e = e; espan = espan }

let make_ty ty tyspan = { ty = ty; tyspan = tyspan }

let binop_name = function
  | Add -> "+"
  | Sub -> "-"
  | Mul -> "*"
  | Div -> "/"
  | Eq -> "="
  | Ne -> "<>"
  | Lt -> "<"
  | Le -> "<="
  | Gt -> ">"
  | Ge -> ">="
  | And -> "&&"
  | Or -> "||"

let string_of_binop = binop_name

let rec string_of_tyexpr tyexpr =
  match tyexpr.ty with
  | TyName name -> name
  | TyCollection element -> "collection " ^ string_of_tyexpr element
  | TyTuple elements -> "(" ^ String.concat ", " (List.map string_of_tyexpr elements) ^ ")"