diff --git a/Sources/Core/CMakeLists.txt b/Sources/Core/CMakeLists.txt
index f7d6e64..0eee81a 100644
--- a/Sources/Core/CMakeLists.txt
+++ b/Sources/Core/CMakeLists.txt
@@ -23,6 +23,7 @@ add_library(swiftCore
   Pointer.swift
   Policy.swift
   Sequence.swift
+  StaticString.swift
   Swift.swift
   UInt.swift
   UInt8.swift
diff --git a/Sources/Core/CompilerProtocols.swift b/Sources/Core/CompilerProtocols.swift
index 9f04ca2..2fa88f6 100644
--- a/Sources/Core/CompilerProtocols.swift
+++ b/Sources/Core/CompilerProtocols.swift
@@ -38,3 +38,13 @@ public protocol RawRepresentable {
   var rawValue: RawValue { get }
   init?(rawValue: RawValue)
 }
+
+public protocol _ExpressibleByBuiltinStringLiteral {
+  init(_builtinStringLiteral start: Builtin.RawPointer, utf8CodeUnitCount: Builtin.Word, isASCII: Builtin.Int1)
+}
+
+public protocol ExpressibleByStringLiteral {
+  associatedtype StringLiteralType: _ExpressibleByBuiltinStringLiteral
+
+  init(stringLiteral value: StringLiteralType)
+}
diff --git a/Sources/Core/Policy.swift b/Sources/Core/Policy.swift
index 791befb..991fa16 100644
--- a/Sources/Core/Policy.swift
+++ b/Sources/Core/Policy.swift
@@ -50,6 +50,10 @@ precedencegroup NilCoalescingPrecedence {
   higherThan: ComparisonPrecedence
 }
 
+precedencegroup CastingPrecedence {
+  higherThan: NilCoalescingPrecedence
+}
+
 precedencegroup AdditionPrecedence {
   associativity: left
   higherThan: NilCoalescingPrecedence
diff --git a/Sources/Core/StaticString.swift b/Sources/Core/StaticString.swift
new file mode 100644
index 0000000..3e22f3b
--- /dev/null
+++ b/Sources/Core/StaticString.swift
@@ -0,0 +1,79 @@
+// Copyright © 2022 Max Desiatov <max@desiatov.com>.
+// All Rights Reserved.
+// SPDX-License-Identifier: BSD-3
+
+@frozen
+public struct StaticString {
+  /// `StaticString` stores either a pointer to null-terminated string data, or a single unicode scalar if possible.
+  @usableFromInline
+  internal var _startPtrOrData: Builtin.Word
+
+  @usableFromInline
+  internal var _utf8CodeUnitCount: Builtin.Word
+
+  /// Flags indicating how `StaticString` storage is used.
+  /// Only two bits are used.
+  /// Bit 1 is set to 1 if `_startPtrOrData` contains a Unicode scalar, 0 otherwise.
+  /// Bit 2 is set to 1 if `_startPtrOrData` is a pointer to an ASCII string, or stores an ASCII scalar value.
+  @usableFromInline
+  internal var _flags: Builtin.Int8
+
+  @_transparent
+  public init() {
+    self = ""
+  }
+
+  @usableFromInline
+  @_transparent
+  internal init(
+    _start: Builtin.RawPointer,
+    utf8CodeUnitCount: Builtin.Word,
+    isASCII: Builtin.Int1
+  ) {
+    _startPtrOrData = Builtin.ptrtoint_Word(_start)
+    _utf8CodeUnitCount = utf8CodeUnitCount
+
+    // First bit indicates whether `StaticString` stores a pointer to the null-terminated string.
+    let pointerRepresentationFlag = (0x0 as UInt8)._value
+
+    // Second bit tells if this string is ASCII.
+    let asciiFlag = (0x2 as UInt8)._value
+    _flags = Bool(isASCII) ? asciiFlag : pointerRepresentationFlag
+  }
+
+  @_alwaysEmitIntoClient
+  @_transparent
+  internal var unsafeRawPointer: Builtin.RawPointer {
+    Builtin.inttoptr_Word(_startPtrOrData)
+  }
+
+  @_transparent
+  public var hasPointerRepresentation: Bool {
+    return (UInt8(_flags) & 0x1) == 0
+  }
+
+  @_transparent
+  public var isASCII: Bool {
+    return (UInt8(_flags) & 0x2) != 0
+  }
+}
+
+extension StaticString: _ExpressibleByBuiltinStringLiteral {
+  @_effects(readonly)
+  @_transparent
+  public init(_builtinStringLiteral start: Builtin.RawPointer, utf8CodeUnitCount: Builtin.Word, isASCII: Builtin.Int1) {
+    self = StaticString(
+      _start: start,
+      utf8CodeUnitCount: utf8CodeUnitCount,
+      isASCII: isASCII
+    )
+  }
+}
+
+extension StaticString: ExpressibleByStringLiteral {
+  @_effects(readonly)
+  @_transparent
+  public init(stringLiteral value: StaticString) {
+    self = value
+  }
+}