Hex!

3 files changed, 35 insertions, 1 deletions

diff --git a/src/gleam/bit_array.gleam b/src/gleam/bit_array.gleam
index b85782d..79860e9 100644
--- a/src/gleam/bit_array.gleam
+++ b/src/gleam/bit_array.gleam
@@ -147,3 +147,11 @@ pub fn base64_url_decode(encoded: String) -> Result(BitArray, Nil) {
   |> string.replace("_", "/")
   |> base64_decode()
 }
+
+@external(erlang, "binary", "encode_hex")
+@external(javascript, "../gleam_stdlib.mjs", "base16_encode")
+pub fn base16_encode(input: BitArray) -> String
+
+@external(erlang, "gleam_stdlib", "base16_decode")
+@external(javascript, "../gleam_stdlib.mjs", "base16_decode")
+pub fn base16_decode(input: String) -> Result(BitArray, Nil)
diff --git a/src/gleam_stdlib.erl b/src/gleam_stdlib.erl
index 0ac4747..0e2136f 100644
--- a/src/gleam_stdlib.erl
+++ b/src/gleam_stdlib.erl
@@ -13,7 +13,7 @@
     decode_tuple5/1, decode_tuple6/1, tuple_get/2, classify_dynamic/1, print/1,
     println/1, print_error/1, println_error/1, inspect/1, float_to_string/1,
     int_from_base_string/2, utf_codepoint_list_to_string/1, contains_string/2,
-    crop_string/2
+    crop_string/2, base16_decode/1
 ]).
 
 %% Taken from OTP's uri_string module
@@ -490,3 +490,10 @@ crop_string(String, Prefix) ->
 
 contains_string(String, Substring) ->
     is_bitstring(string:find(String, Substring)).
+
+base16_decode(String) ->
+    try
+        {ok, binary:decode_hex(String)}
+    catch
+        _:_ -> {error, nil}
+    end.
diff --git a/src/gleam_stdlib.mjs b/src/gleam_stdlib.mjs
index 645e22a..2a1a6cf 100644
--- a/src/gleam_stdlib.mjs
+++ b/src/gleam_stdlib.mjs
@@ -842,3 +842,22 @@ export function inspectBitArray(bits) {
 export function inspectUtfCodepoint(codepoint) {
   return `//utfcodepoint(${String.fromCodePoint(codepoint.value)})`;
 }
+
+export function base16_encode(bit_array) {
+  let result = "";
+  for (const byte of bit_array.buffer) {
+    result += byte.toString(16).padStart(2, "0").toUpperCase();
+  }
+  return result;
+}
+
+export function base16_decode(string) {
+  const bytes = new Uint8Array(string.length / 2);
+  for (let i = 0; i < string.length; i += 2) {
+    const a = parseInt(string[i], 16);
+    const b = parseInt(string[i + 1], 16);
+    if (isNaN(a) || isNaN(b)) return new Error(Nil);
+    bytes[i / 2] = a * 16 + b;
+  }
+  return new Ok(new BitArray(bytes));
+}