Added to/from BitArray support

Implemeted:
- `Ulid` creation from a `BitArray`
- `Ulid` conversion to a `BitArray`

README.md

@@ -69,8 +69,9 @@ pub fn main() {
 }
 ```
 # Advanced Use
-In case one needs to create ULIDs out of predefined constituents
-(timestamp and random), or extract them:
+In case one needs to create or outpur ULIDs out of
+- predefined constituents (timestamp and random)
+- binary representation
 
 ```gleam
 import gleam/erlang
@@ -80,7 +81,7 @@ import gleam/list
 import gleam/result
 import gleam/string
 import gleam/bool
-import gulid.{from_parts, from_tuple, to_parts}
+import gulid.{from_parts, from_tuple, to_parts, from_bitarray, to_bitarray}
 
 pub fn main() {
   let ulid =
@@ -103,6 +104,22 @@ pub fn main() {
   let same_ulid = from_tuple(#(timestamp, random))
 
   io.println("Same ulids? " <> { bool.to_string(same_ulid == ulid) })
+
+  // Ulid from a binary
+  let assert Ok(bin_ulid) =
+    <<
+      erlang.system_time(erlang.Millisecond):big-48,
+      int.random(9_999_999_999):big-80,
+    >>
+    |> from_bitarray
+  io.println("Ulid from a bitarray: ")
+  io.debug(bin_ulid)
+
+  // Ulid to a bitarray
+  io.println("Ulid to binary: ")
+  bin_ulid
+  |> to_bitarray
+  |> io.debug
 }
 
 @external(erlang, "calendar", "system_time_to_rfc3339")

gleam.toml

@@ -1,5 +1,5 @@
 name = "gulid"
-version = "0.0.2"
+version = "0.0.3"
 
 description = "ULID implementation in Gleam (Erlang target only)"
 licences = ["Apache-2.0"]

src/examples/example2.gleam

@@ -5,7 +5,9 @@ import gleam/io
 import gleam/list
 import gleam/result
 import gleam/string
-import gulid.{from_parts, from_tuple, to_parts, to_string_function}
+import gulid.{
+  from_bitarray, from_parts, from_tuple, to_parts, to_string_function,
+}
 
 pub fn main() {
   let to_string = to_string_function()
@@ -32,6 +34,22 @@ pub fn main() {
   )
 
   io.println("Same ulids? " <> { bool.to_string(same_ulid == ulid) })
+
+  // Ulid from a binary
+  let assert Ok(bin_ulid) =
+    <<
+      erlang.system_time(erlang.Millisecond):big-48,
+      int.random(9_999_999_999):big-80,
+    >>
+    |> from_bitarray
+  io.println("Ulid from a bitarray: ")
+  io.debug(bin_ulid)
+
+  // Ulid to a bitarray
+  io.println("Ulid to binary: ")
+  bin_ulid
+  |> gulid.to_bitarray
+  |> io.debug
 }
 
 @external(erlang, "calendar", "system_time_to_rfc3339")

src/gulid.gleam

@@ -62,7 +62,7 @@ pub fn to_string_function() -> fn(Ulid) -> String {
     // to string
     let assert Ok(ulid_str) =
       ulid
-      |> to_bitarray
+      |> to_bitarray_130bits
       |> encode_to_string_with_accumulator("", base32_array)
 
     ulid_str
@@ -97,7 +97,7 @@ pub fn new_as_string() -> String {
 }
 
 /// Builds a `Ulid` value from given `BitArray`. Returns `Ok` with `Ulid` value
-/// on success or `UlidError` otherwise.
+/// on success or `Error(UlidError)` otherwise.
 pub fn from_bitarray(array: BitArray) -> Result(Ulid, UlidError) {
   case array {
     <<ulid:bits-128>> -> Ok(Ulid(ulid))
@@ -239,6 +239,12 @@ pub fn from_tuple(parts: #(Int, Int)) -> Ulid {
   from_parts(timestamp: parts.0, random: parts.1)
 }
 
+/// Returns a binary representation of given `Ulid` value
+pub fn to_bitarray(ulid: Ulid) -> BitArray {
+  let Ulid(result) = ulid
+  <<result:bits>>
+}
+
 //-- Private stuff
 
 // Crockford base32 encoding characters
@@ -276,8 +282,7 @@ fn encode_to_string_with_accumulator(
   }
 }
 
-/// Returns a binary representation of givem `Ulid` value
-fn to_bitarray(ulid: Ulid) -> BitArray {
-  let Ulid(result) = ulid
-  <<0:2, result:bits>>
+/// Returns a binary representation of given `Ulid` value, expanded to 130 bits
+fn to_bitarray_130bits(ulid: Ulid) -> BitArray {
+  <<0:2, to_bitarray(ulid):bits>>
 }

test/gulid_test.gleam

@@ -77,3 +77,19 @@ pub fn from_parts_test() {
   ts |> should.equal(date_time)
   rnd |> should.equal(random)
 }
+
+pub fn from_bitarray_success_test() {
+  <<int.random(99_999_999):big-128>>
+  |> gulid.from_bitarray
+  |> should.be_ok
+}
+
+pub fn from_bitarray_fail_test() {
+  <<int.random(99_999_999):big-130>>
+  |> gulid.from_bitarray
+  |> should.be_error
+}
+
+pub fn to_bitarray_test() {
+  let assert <<_:unsigned-128>> = gulid.to_bitarray(new())
+}