1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
open Ast
let is_sep_name = function Some "separator" -> true | _ -> false
(*
--# Write CSV file
--#
--# Writes a DataFrame to a CSV file.
--#
--# @name write_csv
--# @param df :: DataFrame The data to write.
--# @param path :: String The output path.
--# @param separator :: String (Optional) Field separator (default ",").
--# @return :: Null
--# @example
--# write_csv(df, "output.csv")
--# @family dataframe
--# @seealso read_csv
--# @export
*)
let register ~write_csv_fn env =
Env.add "write_csv"
(make_builtin_named ~name:"write_csv" ~variadic:true 2 (fun named_args _env ->
(* Extract named arguments *)
let sep = List.fold_left (fun acc (name, v) ->
match name, v with
| n, VString s when is_sep_name n -> s
| _ -> acc
) "," named_args in
(* Extract positional arguments *)
let args = List.filter (fun (name, _) ->
not (is_sep_name name)
) named_args |> List.map snd in
match args with
| [VDataFrame df; VString path] ->
(match write_csv_fn ~sep df.arrow_table path with
| Ok () -> (VNA NAGeneric)
| Error msg -> Error.make_error FileError (Printf.sprintf "File Error: %s." msg))
| [_; VString _] -> Error.type_error "Function `write_csv` expects a DataFrame as first argument."
| [VDataFrame _; _] -> Error.type_error "Function `write_csv` expects a String path as second argument."
| [_; _] -> Error.type_error "Function `write_csv` expects (DataFrame, String)."
| _ -> Error.make_error ArityError "Function `write_csv` takes exactly 2 positional arguments (dataframe, path)."
))
env