Writing Files in OCaml

Here’s the translation of the Go code to OCaml, along with explanations in Markdown format suitable for Hugo:

Writing files in OCaml follows similar patterns to the ones we saw earlier for reading.

open Printf

(* Helper function to handle exceptions *)
let check_exn f x =
  try f x with
  | e -> failwith (Printexc.to_string e)

let () =
  (* To start, here's how to dump a string (or just bytes) into a file. *)
  let d1 = "hello\nocaml\n" in
  check_exn (Sys.write_file "/tmp/dat1" d1) ();

  (* For more granular writes, open a file for writing. *)
  let oc = open_out "/tmp/dat2" in

  (* It's idiomatic to use a try-finally block to ensure the file is closed *)
  try
    (* You can write strings as you'd expect. *)
    let d2 = "some\n" in
    output_string oc d2;
    printf "wrote %d bytes\n" (String.length d2);

    (* A write_string function is available in the Printf module. *)
    let n3 = fprintf oc "writes\n" in
    printf "wrote %d bytes\n" n3;

    (* Flush writes to ensure they're written to the file. *)
    flush oc;

    (* OCaml provides buffered output channels. *)
    let n4 = fprintf oc "buffered\n" in
    printf "wrote %d bytes\n" n4;

    (* Use flush to ensure all buffered operations have been applied. *)
    flush oc;
  finally
    close_out oc

Try running the file-writing code.

$ ocaml writing_files.ml
wrote 5 bytes
wrote 7 bytes
wrote 9 bytes

Then check the contents of the written files.

$ cat /tmp/dat1
hello
ocaml
$ cat /tmp/dat2
some
writes
buffered

Next we’ll look at applying some of the file I/O ideas we’ve just seen to the stdin and stdout streams.

Time Formatting Parsing in OCaml

Number Parsing in OCaml

Learn X By Example

Title here

Writing Files in OCaml