binary -> bit string

1 files changed, 54 insertions, 0 deletions

diff --git a/src/gleam/bit_string.gleam b/src/gleam/bit_string.gleam
new file mode 100644
index 0000000..d6fe14d
--- /dev/null
+++ b/src/gleam/bit_string.gleam
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+//// Working with raw bit string data.
+//// The BitString type should be used instead of a String type when not utf8
+//// encoded.
+
+// TODO: determine which of these functions once we have bit string syntax
+pub external type BitString
+
+/// Convert a utf8 String type into a raw Bitstring type.
+///
+pub external fn from_string(String) -> Bitstring =
+  "gleam_stdlib" "identity"
+
+/// Returns an integer which is the number of bytes in the bit string.
+///
+pub external fn byte_size(Bitstring) -> Int =
+  "erlang" "byte_size"
+
+/// Create a new bit string by joining two binaries.
+///
+/// ## Examples
+///
+///    > append(to: from_string("butter"), suffix: from_string("fly"))
+///    from_string("butterfly")
+///
+pub external fn append(first: Bitstring, second: Bitstring) -> Bitstring =
+  "gleam_stdlib" "bit_string_append"
+
+/// Extracts part of a bit string.
+///
+/// Bitstring part will start at given position and continue up to specified
+/// length.
+/// A negative length can be used to extract bytes at the end of a bit string.
+///
+pub external fn part(
+  string: Bitstring,
+  position: Int,
+  length: Int,
+) -> Result(Bitstring, Nil) =
+  "gleam_stdlib" "bit_string_part_"
+
+/// Convert an integer to unsigned 32 bits.
+///
+/// Returns an error if integer is less than zero or equal to or larger than
+/// 2^32.
+///
+pub external fn int_to_u32(Int) -> Result(Bitstring, Nil) =
+  "gleam_stdlib" "bit_string_int_to_u32"
+
+/// Convert unsigned 32 bits to an integer.
+///
+/// Returns an error if the bit string is not 32 bits in length.
+///
+pub external fn int_from_u32(Bitstring) -> Result(Int, Nil) =
+  "gleam_stdlib" "bit_string_int_from_u32"