diff --git a/prototype/Doubt.xcodeproj/project.pbxproj b/prototype/Doubt.xcodeproj/project.pbxproj
index b0bcf44f6..1f15fd867 100644
--- a/prototype/Doubt.xcodeproj/project.pbxproj
+++ b/prototype/Doubt.xcodeproj/project.pbxproj
@@ -38,7 +38,7 @@
 		D4AAE5401B5AE2D0004E581F /* Array.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4AAE5351B5AE2D0004E581F /* Array.swift */; };
 		D4AAE5421B5AE2D0004E581F /* Doc.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4AAE5371B5AE2D0004E581F /* Doc.swift */; };
 		D4AAE5451B5AE2D0004E581F /* Operators.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4AAE53A1B5AE2D0004E581F /* Operators.swift */; };
-		D4AAE5471B5AE2D0004E581F /* Prelude.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4AAE53C1B5AE2D0004E581F /* Prelude.swift */; };
+		D4AAE5471B5AE2D0004E581F /* Optional.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4AAE53C1B5AE2D0004E581F /* Optional.swift */; };
 		D4AAE5481B5AE2D0004E581F /* String.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4AAE53D1B5AE2D0004E581F /* String.swift */; };
 		D4AAE5491B5AE2D0004E581F /* StringLiteralConvertible.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4AAE53E1B5AE2D0004E581F /* StringLiteralConvertible.swift */; };
 		D4AAE54A1B5AE2D0004E581F /* Syntax.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4AAE53F1B5AE2D0004E581F /* Syntax.swift */; };
@@ -123,7 +123,7 @@
 		D4AAE5351B5AE2D0004E581F /* Array.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Array.swift; sourceTree = "<group>"; };
 		D4AAE5371B5AE2D0004E581F /* Doc.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Doc.swift; sourceTree = "<group>"; };
 		D4AAE53A1B5AE2D0004E581F /* Operators.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Operators.swift; sourceTree = "<group>"; };
-		D4AAE53C1B5AE2D0004E581F /* Prelude.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Prelude.swift; sourceTree = "<group>"; };
+		D4AAE53C1B5AE2D0004E581F /* Optional.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Optional.swift; sourceTree = "<group>"; };
 		D4AAE53D1B5AE2D0004E581F /* String.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = String.swift; sourceTree = "<group>"; };
 		D4AAE53E1B5AE2D0004E581F /* StringLiteralConvertible.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = StringLiteralConvertible.swift; sourceTree = "<group>"; };
 		D4AAE53F1B5AE2D0004E581F /* Syntax.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Syntax.swift; sourceTree = "<group>"; };
@@ -233,7 +233,7 @@
 				D4AAE5351B5AE2D0004E581F /* Array.swift */,
 				D4AAE5371B5AE2D0004E581F /* Doc.swift */,
 				D4AAE53A1B5AE2D0004E581F /* Operators.swift */,
-				D4AAE53C1B5AE2D0004E581F /* Prelude.swift */,
+				D4AAE53C1B5AE2D0004E581F /* Optional.swift */,
 				D4AAE53D1B5AE2D0004E581F /* String.swift */,
 				D4AAE53E1B5AE2D0004E581F /* StringLiteralConvertible.swift */,
 				D4AAE53F1B5AE2D0004E581F /* Syntax.swift */,
@@ -459,7 +459,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				D4AAE5471B5AE2D0004E581F /* Prelude.swift in Sources */,
+				D4AAE5471B5AE2D0004E581F /* Optional.swift in Sources */,
 				D4413FEF1BB06D4C00E3C3C1 /* Dictionary.swift in Sources */,
 				D4AAE5481B5AE2D0004E581F /* String.swift in Sources */,
 				D4D7F3171BBB22E500AAB0C0 /* Hash.swift in Sources */,
diff --git a/prototype/Doubt/Prelude.swift b/prototype/Doubt/Optional.swift
similarity index 100%
rename from prototype/Doubt/Prelude.swift
rename to prototype/Doubt/Optional.swift