diff --git a/locale/locale.ha b/locale/locale.ha
new file mode 100644
index 0000000..bf39c8c
--- /dev/null
+++ b/locale/locale.ha
@@ -0,0 +1,61 @@
+use errors;
+use fmt;
+use strings;
+
+// A parsed locale name.
+export type locale = struct {
+	language: str,
+	country:  str,
+	encoding: str,
+	modifier: str,
+};
+
+// Parses a [[locale]] name of the form:
+// 
+//   lang_COUNTRY.ENCODING@MODIFIER
+// 
+// Where _COUNTRY, .ENCODING, and @MODIFIER may be omitted. The function
+// returns a [[locale]], or [[errors::invalid]] if the input cannot be parsed.
+// All memory is borrowed from the input.
+export fn parse_locale(in: str) (locale | errors::invalid) = {
+	let (in, modifier) = strings::rcut(in, "@");
+	if (strings::compare(in, "") == 0) return void: errors::invalid;
+	let (in, encoding) = strings::rcut(in, ".");
+	if (strings::compare(in, "") == 0) return void: errors::invalid;
+	let (in, country) = strings::rcut(in, "_");
+	if (strings::compare(in, "") == 0) return void: errors::invalid;
+	return locale {
+		language = in,
+		country  = country,
+		encoding = encoding,
+		modifier = modifier,
+	};
+};
+
+// Formats a [[locale]]. The caller must free the return value.
+export fn format_locale(local: locale) str = {
+	let output = strings::dup(local.language);
+	if (strings::compare(local.country, "") != 0) {
+		let new_output = strings::join("_", output, local.country);
+		free(output);
+		output = new_output;
+	};
+	if (strings::compare(local.encoding, "") != 0) {
+		let new_output = strings::join(".", output, local.encoding);
+		free(output);
+		output = new_output;
+	};
+	if (strings::compare(local.modifier, "") != 0) {
+		let new_output = strings::join("@", output, local.modifier);
+		free(output);
+		output = new_output;
+	};
+	return output;
+};
+
+// Checks if two [[locale]]s are equal.
+export fn locale_equal(a: locale, b: locale) bool =
+	strings::compare(a.language, b.language) == 0 &&
+	strings::compare(a.country,  b.country ) == 0 &&
+	strings::compare(a.encoding, b.encoding) == 0 &&
+	strings::compare(a.modifier, b.modifier) == 0;
diff --git a/locale/locale_test.ha b/locale/locale_test.ha
new file mode 100644
index 0000000..ab8a743
--- /dev/null
+++ b/locale/locale_test.ha
@@ -0,0 +1,143 @@
+use fmt;
+use errors;
+use strings;
+
+@test fn parse_locale_full() void = {
+	let local = match(parse_locale("lang_COUNTRY.ENCODING@MODIFIER")) {
+	case let local: locale => yield local;
+	case                   => abort("error");
+	};
+	fmt::printf("[{}]\n", local.language)!;
+	assert(strings::compare(local.language, "lang") == 0);
+	fmt::printf("[{}]\n", local.country)!;
+	assert(strings::compare(local.country, "COUNTRY") == 0);
+	fmt::printf("[{}]\n", local.encoding)!;
+	assert(strings::compare(local.encoding, "ENCODING") == 0);
+	fmt::printf("[{}]\n", local.modifier)!;
+	assert(strings::compare(local.modifier, "MODIFIER") == 0);
+};
+
+@test fn parse_locale_sparse_a() void = {
+	let local = match(parse_locale("lang.ENCODING@MODIFIER")) {
+	case let local: locale => yield local;
+	case                   => abort("error");
+	};
+	fmt::printf("[{}]\n", local.language)!;
+	assert(strings::compare(local.language, "lang") == 0);
+	fmt::printf("[{}]\n", local.country)!;
+	assert(strings::compare(local.country, "") == 0);
+	fmt::printf("[{}]\n", local.encoding)!;
+	assert(strings::compare(local.encoding, "ENCODING") == 0);
+	fmt::printf("[{}]\n", local.modifier)!;
+	assert(strings::compare(local.modifier, "MODIFIER") == 0);
+};
+
+@test fn parse_locale_sparse_b() void = {
+	let local = match(parse_locale("lang.ENCODING")) {
+	case let local: locale => yield local;
+	case                   => abort("error");
+	};
+	fmt::printf("[{}]\n", local.language)!;
+	assert(strings::compare(local.language, "lang") == 0);
+	fmt::printf("[{}]\n", local.country)!;
+	assert(strings::compare(local.country, "") == 0);
+	fmt::printf("[{}]\n", local.encoding)!;
+	assert(strings::compare(local.encoding, "ENCODING") == 0);
+	fmt::printf("[{}]\n", local.modifier)!;
+	assert(strings::compare(local.modifier, "") == 0);
+};
+
+@test fn parse_locale_sparse_c() void = {
+	let local = match(parse_locale("lang")) {
+	case let local: locale => yield local;
+	case                   => abort("error");
+	};
+	fmt::printf("[{}]\n", local.language)!;
+	assert(strings::compare(local.language, "lang") == 0);
+	fmt::printf("[{}]\n", local.country)!;
+	assert(strings::compare(local.country, "") == 0);
+	fmt::printf("[{}]\n", local.encoding)!;
+	assert(strings::compare(local.encoding, "") == 0);
+	fmt::printf("[{}]\n", local.modifier)!;
+	assert(strings::compare(local.modifier, "") == 0);
+};
+
+@test fn parse_locale_error() void = {
+	let local = match(parse_locale("_COUNTRY.ENCODING@MODIFIER")) {
+	case errors::invalid => void;
+	case                 => abort("error");
+	};
+};
+
+@test fn format_locale_a() void = {
+	let string = format_locale(locale {
+		language = "lang",
+		country  = "COUNTRY",
+		encoding = "ENCODING",
+		modifier = "MODIFIER",
+	});
+	defer free(string);
+	fmt::printf("[{}]\n", string)!;
+	assert(strings::compare(string, "lang_COUNTRY.ENCODING@MODIFIER") == 0);
+};
+
+@test fn format_locale_b() void = {
+	let string = format_locale(locale {
+		language = "lang",
+		country  = "COUNTRY",
+		modifier = "MODIFIER",
+		...
+	});
+	defer free(string);
+	fmt::printf("[{}]\n", string)!;
+	assert(strings::compare(string, "lang_COUNTRY@MODIFIER") == 0);
+};
+
+@test fn format_locale_c() void = {
+	let string = format_locale(locale {
+		language = "lang",
+		...
+	});
+	defer free(string);
+	fmt::printf("[{}]\n", string)!;
+	assert(strings::compare(string, "lang") == 0);
+};
+
+@test fn locale_equal() void = {
+	assert(locale_equal(locale {
+		language = "lang",
+		country  = "COUNTRY",
+		encoding = "ENCODING",
+		modifier = "MODIFIER",
+	},
+	locale {
+		language = "lang",
+		country  = "COUNTRY",
+		encoding = "ENCODING",
+		modifier = "MODIFIER",
+	}));
+	assert(!locale_equal(locale {
+		language = "lang",
+		country  = "COUNTRY",
+		encoding = "ENCODING",
+		modifier = "MODIFIER",
+	},
+	locale {
+		language = "foo",
+		country  = "COUNTRY",
+		encoding = "ENCODING",
+		modifier = "MODIFIER",
+	}));
+	assert(!locale_equal(locale {
+		language = "lang",
+		encoding = "ENCODING",
+		modifier = "MODIFIER",
+		...
+	},
+	locale {
+		language = "lang",
+		country  = "COUNTRY",
+		encoding = "ENCODING",
+		...
+	}));
+};