commit 538fd90b0cadee4ba62a7980ff06d73369dd7b6e
Author: Erica Marigold <hi@devcomp.xyz>
Date:   Mon Apr 1 11:37:43 2024 +0530

    feat: initial Result and barebones Option implementation

diff --git a/.vscode/settings.json b/.vscode/settings.json
new file mode 100644
index 0000000..167d616
--- /dev/null
+++ b/.vscode/settings.json
@@ -0,0 +1,13 @@
+{
+  "luau-lsp.inlayHints.variableTypes": true,
+  "luau-lsp.inlayHints.functionReturnTypes": true,
+  "luau-lsp.inlayHints.parameterNames": "all",
+  "luau-lsp.inlayHints.parameterTypes": true,
+  "luau-lsp.inlayHints.typeHintMaxLength": 50,
+  "luau-lsp.require.mode": "relativeToFile",
+  "luau-lsp.require.directoryAliases": {
+    "@lune/": "~/.lune/.typedefs/0.8.2/"
+  },
+
+  "editor.formatOnSave": true
+}
diff --git a/aftman.toml b/aftman.toml
new file mode 100644
index 0000000..208aba1
--- /dev/null
+++ b/aftman.toml
@@ -0,0 +1,5 @@
+[tools]
+lune = "lune-org/lune@0.8.2"
+stylua = "JohnnyMorganz/StyLua@0.20.0"
+luau-lsp = "JohnnyMorganz/luau-lsp@1.27.0"
+darklua = "seaofvoices/darklua@0.13.0"
diff --git a/lib/option.luau b/lib/option.luau
new file mode 100644
index 0000000..5d7fce6
--- /dev/null
+++ b/lib/option.luau
@@ -0,0 +1,34 @@
+local Option = {}
+export type Option<T> = typeof(Option) & {
+    _optValue: T?,
+    typeId: "Option"
+}
+
+function None<T>(): Option<T>
+    return Option.new(nil) :: Option<T>
+end
+
+function Some<T>(val: T): Option<T>
+    return Option.new(val) :: Option<T>
+end
+
+function Option.new<T>(val: T?)
+    return setmetatable({
+        _optValue = val,
+        typeId = "Option"
+    } :: Option<T>, {
+        __index = Option,
+        __tostring = function(self)
+            -- Return formatted enum variants too
+
+            return `{self.typeId}<T>`
+        end
+    })
+end
+
+return {
+    -- TODO: Implement Option utility methods
+    Option = Option,
+    Some = Some,
+    None = None
+}
\ No newline at end of file
diff --git a/lib/result.luau b/lib/result.luau
new file mode 100644
index 0000000..8be4961
--- /dev/null
+++ b/lib/result.luau
@@ -0,0 +1,277 @@
+local option = require("option")
+local Option = option.Option
+type Option<T> = option.Option<T>
+local None = option.None
+local Some = option.Some
+
+local Result = {}
+export type Result<T, E> = typeof(Result) & {
+	_value: T,
+	_error: E,
+	typeId: "Result",
+}
+
+function Ok<T, E>(val: T): Result<T, E>
+	return Result.new(val, (nil :: unknown) :: E)
+end
+
+function Err<T, E>(err: E): Result<T, E>
+	return Result.new((nil :: unknown) :: T, err)
+end
+
+function Result.new<T, E>(val: T, err: E)
+	return setmetatable(
+		{
+			_value = val,
+			_error = err,
+			typeId = "Result",
+		} :: Result<T, E>,
+		{
+			__index = Result,
+			__tostring = function<T, E>(self: Result<T, E>)
+				if self:isOk() then
+					return `{self.typeId}::Ok<{self._value}>`
+				end
+
+				if self:isErr() then
+					return `{self.typeId}::Err<{self._error}>`
+				end
+
+				return `{self.typeId}}<T, E>`
+			end,
+			__eq = function<T, E>(self: Result<T, E>, other: Result<T, E>)
+				if
+					typeof(self._value) ~= "table"
+					and typeof(self._error) ~= "table"
+					and typeof(other._value) ~= "table"
+					and typeof(other._error) ~= "table"
+				then
+					return self._value == other._value and self._error == other._error
+				end
+
+				error(`eq: cannot compare {tostring(self)} and {tostring(other)}`)
+			end,
+
+			-- TODO: Implement __iter, once iterators traits exist
+		}
+	)
+end
+
+function Result.isOk<T, E>(self: Result<T, E>): boolean
+	if self._value == nil then
+		return false
+	end
+
+	return true
+end
+
+function Result.isOkAnd<T, E>(self: Result<T, E>, predicate: (val: T?) -> boolean): boolean
+	return self:isOk() and predicate(self._value)
+end
+
+function Result.isErr<T, E>(self: Result<T, E>)
+	return not self:isOk()
+end
+
+function Result.isErrAnd<T, E>(self: Result<T, E>, predicate: (val: E) -> boolean): boolean
+	if self:isErr() then
+		return predicate(self._error)
+	end
+
+	return false
+end
+
+function Result.ok<T, E>(self: Result<T, E>): Option<T>
+	if self:isOk() then
+		if self._value == nil then
+			return None()
+		end
+
+		return Some(self._value)
+	end
+
+	return None()
+end
+
+function Result.err<T, E>(self: Result<T, E>): Option<E>
+	if self:isErr() then
+		return Option.new(self._error) :: Option<E>
+	end
+
+	return None()
+end
+
+function Result.map<T, E, U>(self: Result<T, E>, op: (val: T) -> U): Result<U, E>
+	if self:isOk() then
+		return Result.new(op(self._value), self._error) :: Result<U, E>
+	end
+
+	return Err(self._error)
+end
+
+function Result.mapOr<T, E, U>(self: Result<T, E>, default: U, op: (val: T) -> U): U
+	if self:isOk() then
+		return op(self._value)
+	end
+
+	return default
+end
+
+function Result.mapOrElse<T, E, U>(self: Result<T, E>, default: (val: E) -> U, op: (val: T) -> U): U
+	if self:isOk() then
+		return op(self._value)
+	end
+
+	return default(self._error)
+end
+
+function Result.mapErr<T, E, F>(self: Result<T, E>, op: (val: E) -> F): Result<T, F>
+	if self:isErr() then
+		return Result.new(self._value, op(self._error))
+	end
+
+	return Ok(self._value)
+end
+
+function Result.inspect<T, E>(self: Result<T, E>, op: (val: T) -> nil): Result<T, E>
+	if self:isOk() then
+		op(self._value)
+	end
+
+	return self
+end
+
+function Result.inspectErr<T, E>(self: Result<T, E>, op: (val: E) -> nil): Result<T, E>
+	if self:isErr() then
+		op(self._error)
+	end
+
+	return self
+end
+
+-- TODO: Iterator traits
+function Result.iter() end
+
+function Result.expect<T, E>(self: Result<T, E>, msg: string): T | never
+	if self:isOk() then
+		return self._value
+	end
+
+	return error(`panic: {msg}; {self._error}`)
+end
+
+function Result.unwrap<T, E>(self: Result<T, E>): T | never
+	if self:isOk() then
+		return self._value
+	end
+
+	return error(`panic: \`Result:unwrap()\` called on an \`Err\` value: {self._error}`)
+end
+
+function Result.unwrapOrDefault<T, E>(self: Result<T, E>): never
+	return error("TODO: Result:unwrapOrDefault()")
+end
+
+function Result.exceptErr<T, E>(self: Result<T, E>, msg: string): E | never
+	if self:isErr() then
+		return self._error
+	end
+
+	return error(`panic: {msg}; {self._error}`)
+end
+
+function Result.unwrapErr<T, E>(self: Result<T, E>): E | never
+	if self:isErr() then
+		return self._error
+	end
+
+	return error(`panic: \`Result:unwrapErr()\` called on an \`Ok\` value: {self._value}`)
+end
+
+-- TODO: How the fuck do I implement this?
+function Result.intoOk<T, E>(self: Result<T, E>) end
+function Result.intoErr<T, E>(self: Result<T, E>) end
+
+function Result.and_<T, E, U>(self: Result<T, E>, res: Result<U, E>): Result<U, E>
+	if self:isOk() then
+		return res
+	end
+
+	return Err(self._error)
+end
+
+function Result.andThen<T, E, U>(self: Result<T, E>, op: (...any) -> any): Result<U, E>
+	if self:isOk() then
+		return op(self._value)
+	end
+
+	return Err(self._error) :: Result<U, E>
+end
+
+function Result.or_<T, E, F>(self: Result<T, E>, res: Result<T, F>): Result<T, F> | never
+	if self:isErr() then
+		return res
+	end
+
+	if self:isOk() then
+		return Ok(self._value) :: Result<T, F>
+	end
+
+	return error("called `Result:or()` with an invalid value")
+end
+
+function Result.orElse<T, E, U>(self: Result<T, E>, op: (x: E) -> Result<T, U>): Result<T, U>
+	if self:isErr() then
+		return op(self._error)
+	end
+
+	return Ok(self._value)
+end
+
+function Result.unwrapOr<T, E>(self: Result<T, E>, default: T): T
+	if self:isOk() then
+		return self._value
+	end
+
+	return default
+end
+
+function Result.unwrapOrElse<T, E>(self: Result<T, E>, op: (x: E) -> T)
+	if self:isOk() then
+		return self._value
+	end
+
+	return op(self._error)
+end
+
+function Result.contains<T, E>(self: Result<T, E>, val: T): boolean
+	if self:isOk() then
+		return self._value == val
+	end
+
+	return false
+end
+
+function Result.containsErr<T, E>(self: Result<T, E>, err: E): boolean
+	if self:isErr() then
+		return self._error == err
+	end
+
+	return false
+end
+
+function Result.transpose<T, E>(self: Result<Option<T>, E>): Option<Result<T, E>>
+	-- TODO: Instead of checking whether values are nil, use
+	-- utility methods for Options once available
+	if self._value == None() then
+		return None()
+	elseif self:isOkAnd(function(val): boolean
+		return val._optValue == nil
+	end) ~= nil then
+		return Some(Ok(self._value._optValue))
+	elseif self:isErr() then
+		return Some(Err(self._error))
+	end
+
+	error("`Result` is not transposable")
+end