diff --git a/src/Codegen/Constraints/StringBuilder.php b/src/Codegen/Constraints/StringBuilder.php
index 8b8631d..1a1dc6d 100644
--- a/src/Codegen/Constraints/StringBuilder.php
+++ b/src/Codegen/Constraints/StringBuilder.php
@@ -7,181 +7,182 @@
 use type Facebook\HackCodegen\{CodegenMethod, HackBuilderValues};
 
 type TStringSchema = shape(
-  'type' => TSchemaType,
-  ?'maxLength' => int,
-  ?'minLength' => int,
-  ?'enum' => vec<string>,
-  ?'hackEnum' => string,
-  ?'generateHackEnum' => bool,
-  ?'pattern' => string,
-  ?'format' => string,
-  ?'sanitize' => shape(
-    'multiline' => bool,
-  ),
-  ?'coerce' => bool,
-  ...
+	'type' => TSchemaType,
+	?'maxLength' => int,
+	?'minLength' => int,
+	?'enum' => vec<string>,
+	?'hackEnum' => string,
+	?'generateHackEnum' => bool,
+	?'pattern' => string,
+	?'format' => string,
+	?'sanitize' => shape(
+		'multiline' => bool,
+	),
+	?'coerce' => bool,
+	...
 );
 
 class StringBuilder extends BaseBuilder<TStringSchema> {
-  protected static string $schema_name = 'Slack\Hack\JsonSchema\Codegen\TStringSchema';
-
-  <<__Override>>
-  public function build(): this {
-    $class = $this->codegenClass()
-      ->addMethod($this->getCheckMethod());
-
-    $properties = vec[];
-    $max_length = $this->typed_schema['maxLength'] ?? null;
-    if ($max_length is nonnull) {
-      $properties[] = $this->codegenProperty('maxLength')
-        ->setType('int')
-        ->setValue($max_length, HackBuilderValues::export());
-    }
-
-    $min_length = $this->typed_schema['minLength'] ?? null;
-    if ($min_length is nonnull) {
-      $properties[] = $this->codegenProperty('minLength')
-        ->setType('int')
-        ->setValue($min_length, HackBuilderValues::export());
-    }
-
-    $pattern = $this->typed_schema['pattern'] ?? null;
-    if ($pattern is nonnull) {
-      $properties[] = $this->codegenProperty('pattern')
-        ->setType('string')
-        ->setValue($pattern, HackBuilderValues::export());
-    }
-
-    $format = $this->typed_schema['format'] ?? null;
-    if ($format is nonnull) {
-      $properties[] = $this->codegenProperty('format')
-        ->setType('string')
-        ->setValue($format, HackBuilderValues::export());
-    }
-
-    $enum = $this->getEnumCodegenProperty();
-    $generateHackEnum = $this->typed_schema['generateHackEnum'] ?? false;
-    if ($enum is nonnull) {
-      if ($generateHackEnum) {
-        $enum = $this->typed_schema['enum'] ?? vec[];
-        $factory = $this->ctx->getHackCodegenFactory();
-        $members = \HH\Lib\Vec\map(
-          $enum,
-          $member ==> $factory->codegenEnumMember(Str\uppercase($member))
-            ->setValue($member, HackBuilderValues::export()),
-        );
-        $enumName = $this->typed_schema['hackEnum'] ?? null;
-        invariant($enumName is string, 'hackEnum is required when generating hack enum.');
-        $enum_obj = $factory->codegenEnum($enumName, 'string')
-          ->addMembers($members)
-          ->setIsAs('string');
-        $this->ctx->getFile()->addEnum($enum_obj);
-      } else {
-        $properties[] = $enum;
-      }
-    } else {
-      invariant(!$generateHackEnum, 'enum is required when generating hack enum');
-    }
-
-    $coerce = $this->typed_schema['coerce'] ?? $this->ctx->getCoerceDefault();
-    $properties[] = $this->codegenProperty('coerce')
-      ->setType('bool')
-      ->setValue($coerce, HackBuilderValues::export());
-
-    $class->addProperties($properties);
-    $this->addBuilderClass($class);
-
-    return $this;
-  }
-
-  protected function getCheckMethod(): CodegenMethod {
-    $hb = $this->getHackBuilder()
-      ->addAssignment(
-        '$typed',
-        'Constraints\StringConstraint::check($input, $pointer, self::$coerce)',
-        HackBuilderValues::literal(),
-      )
-      ->ensureEmptyLine();
-
-    $sanitize = $this->typed_schema['sanitize'] ?? null;
-    $sanitize_string = $this->ctx->getSanitizeStringConfig();
-    if ($sanitize is nonnull && $sanitize_string === null) {
-      throw new \Exception('Specified `sanitize` on a string without providing sanitization functions.');
-    } else if ($sanitize is nonnull && $sanitize_string is nonnull) {
-      if ($sanitize['multiline']) {
-        $sanitization_func = get_function_name_from_function($sanitize_string['multiline']);
-      } else {
-        $sanitization_func = get_function_name_from_function($sanitize_string['uniline']);
-      }
-
-      $hb
-        ->addAssignment('$sanitize_string', "\\$sanitization_func<>", HackBuilderValues::literal())
-        ->addAssignment('$typed', '$sanitize_string($typed)', HackBuilderValues::literal())
-        ->ensureEmptyLine();
-    }
-    if (!($this->typed_schema['generateHackEnum'] ?? false)) {
-      $this->addEnumConstraintCheck($hb);
-    }
-
-    $max_length = $this->typed_schema['maxLength'] ?? null;
-    $min_length = $this->typed_schema['minLength'] ?? null;
-    $pattern = $this->typed_schema['pattern'] ?? null;
-    $format = $this->typed_schema['format'] ?? null;
-
-    if ($pattern is nonnull) {
-      $hb->addMultilineCall('Constraints\StringPatternConstraint::check', vec['$typed', 'self::$pattern', '$pointer']);
-    }
-
-    if ($format is nonnull) {
-      $hb->addMultilineCall('Constraints\StringFormatConstraint::check', vec['$typed', 'self::$format', '$pointer']);
-    }
-
-    if ($max_length is nonnull || $min_length is nonnull) {
-      $hb->addAssignment('$length', '\mb_strlen($typed)', HackBuilderValues::literal());
-    }
-
-    if ($max_length is nonnull) {
-      $hb->addMultilineCall(
-        'Constraints\StringMaxLengthConstraint::check',
-        vec['$length', 'self::$maxLength', '$pointer'],
-      );
-    }
-
-    if ($min_length is nonnull) {
-      $hb->addMultilineCall(
-        'Constraints\StringMinLengthConstraint::check',
-        vec['$length', 'self::$minLength', '$pointer'],
-      );
-    }
-
-    $this->addHackEnumConstraintCheck($hb);
-
-    $hb->addReturn('$typed', HackBuilderValues::literal());
-
-    return $this->codegenCheckMethod()
-      ->addParameters(vec['mixed $input', 'string $pointer'])
-      ->setBody($hb->getCode())
-      ->setReturnType($this->getType());
-  }
-
-  <<__Override>>
-  public function getType(): string {
-    if (Shapes::keyExists($this->typed_schema, 'hackEnum')) {
-      if ($this->typed_schema['generateHackEnum'] ?? false) {
-        return $this->typed_schema['hackEnum'];
-      }
-      return Str\format('\%s', $this->typed_schema['hackEnum']);
-    }
-
-    return 'string';
-  }
-
-  <<__Override>>
-  public function getTypeInfo(): Typing\Type {
-    if ($this->getType() === 'string') {
-      return Typing\TypeSystem::string();
-    }
-    // TODO: Type resolution for hackEnum
-    return Typing\TypeSystem::nonnull();
-  }
+	protected static string $schema_name = 'Slack\Hack\JsonSchema\Codegen\TStringSchema';
+
+	<<__Override>>
+	public function build(): this {
+		$class = $this->codegenClass()
+			->addMethod($this->getCheckMethod());
+
+		$properties = vec[];
+		$max_length = $this->typed_schema['maxLength'] ?? null;
+		if ($max_length is nonnull) {
+			$properties[] = $this->codegenProperty('maxLength')
+				->setType('int')
+				->setValue($max_length, HackBuilderValues::export());
+		}
+
+		$min_length = $this->typed_schema['minLength'] ?? null;
+		if ($min_length is nonnull) {
+			$properties[] = $this->codegenProperty('minLength')
+				->setType('int')
+				->setValue($min_length, HackBuilderValues::export());
+		}
+
+		$pattern = $this->typed_schema['pattern'] ?? null;
+		if ($pattern is nonnull) {
+			$properties[] = $this->codegenProperty('pattern')
+				->setType('string')
+				->setValue($pattern, HackBuilderValues::export());
+		}
+
+		$format = $this->typed_schema['format'] ?? null;
+		if ($format is nonnull) {
+			$properties[] = $this->codegenProperty('format')
+				->setType('string')
+				->setValue($format, HackBuilderValues::export());
+		}
+
+		$enum = $this->getEnumCodegenProperty();
+		$generateHackEnum = $this->typed_schema['generateHackEnum'] ?? false;
+		if ($enum is nonnull) {
+			if ($generateHackEnum) {
+				$enum = $this->typed_schema['enum'] ?? vec[];
+				$factory = $this->ctx->getHackCodegenFactory();
+				$members = \HH\Lib\Vec\map(
+					$enum,
+					$member ==> $factory->codegenEnumMember(Str\uppercase($member))
+						->setValue($member, HackBuilderValues::export()),
+				);
+				$enumName = $this->typed_schema['hackEnum'] ?? null;
+				invariant($enumName is string, 'hackEnum is required when generating hack enum.');
+				invariant(!Str\contains($enumName, '\\'), 'hackEnum must not contain a slash.');
+				$enum_obj = $factory->codegenEnum($enumName, 'string')
+					->addMembers($members)
+					->setIsAs('string');
+				$this->ctx->getFile()->addEnum($enum_obj);
+			} else {
+				$properties[] = $enum;
+			}
+		} else {
+			invariant(!$generateHackEnum, 'enum is required when generating hack enum');
+		}
+
+		$coerce = $this->typed_schema['coerce'] ?? $this->ctx->getCoerceDefault();
+		$properties[] = $this->codegenProperty('coerce')
+			->setType('bool')
+			->setValue($coerce, HackBuilderValues::export());
+
+		$class->addProperties($properties);
+		$this->addBuilderClass($class);
+
+		return $this;
+	}
+
+	protected function getCheckMethod(): CodegenMethod {
+		$hb = $this->getHackBuilder()
+			->addAssignment(
+				'$typed',
+				'Constraints\StringConstraint::check($input, $pointer, self::$coerce)',
+				HackBuilderValues::literal(),
+			)
+			->ensureEmptyLine();
+
+		$sanitize = $this->typed_schema['sanitize'] ?? null;
+		$sanitize_string = $this->ctx->getSanitizeStringConfig();
+		if ($sanitize is nonnull && $sanitize_string === null) {
+			throw new \Exception('Specified `sanitize` on a string without providing sanitization functions.');
+		} else if ($sanitize is nonnull && $sanitize_string is nonnull) {
+			if ($sanitize['multiline']) {
+				$sanitization_func = get_function_name_from_function($sanitize_string['multiline']);
+			} else {
+				$sanitization_func = get_function_name_from_function($sanitize_string['uniline']);
+			}
+
+			$hb
+				->addAssignment('$sanitize_string', "\\$sanitization_func<>", HackBuilderValues::literal())
+				->addAssignment('$typed', '$sanitize_string($typed)', HackBuilderValues::literal())
+				->ensureEmptyLine();
+		}
+		if (!($this->typed_schema['generateHackEnum'] ?? false)) {
+			$this->addEnumConstraintCheck($hb);
+		}
+
+		$max_length = $this->typed_schema['maxLength'] ?? null;
+		$min_length = $this->typed_schema['minLength'] ?? null;
+		$pattern = $this->typed_schema['pattern'] ?? null;
+		$format = $this->typed_schema['format'] ?? null;
+
+		if ($pattern is nonnull) {
+			$hb->addMultilineCall('Constraints\StringPatternConstraint::check', vec['$typed', 'self::$pattern', '$pointer']);
+		}
+
+		if ($format is nonnull) {
+			$hb->addMultilineCall('Constraints\StringFormatConstraint::check', vec['$typed', 'self::$format', '$pointer']);
+		}
+
+		if ($max_length is nonnull || $min_length is nonnull) {
+			$hb->addAssignment('$length', '\mb_strlen($typed)', HackBuilderValues::literal());
+		}
+
+		if ($max_length is nonnull) {
+			$hb->addMultilineCall(
+				'Constraints\StringMaxLengthConstraint::check',
+				vec['$length', 'self::$maxLength', '$pointer'],
+			);
+		}
+
+		if ($min_length is nonnull) {
+			$hb->addMultilineCall(
+				'Constraints\StringMinLengthConstraint::check',
+				vec['$length', 'self::$minLength', '$pointer'],
+			);
+		}
+
+		$this->addHackEnumConstraintCheck($hb);
+
+		$hb->addReturn('$typed', HackBuilderValues::literal());
+
+		return $this->codegenCheckMethod()
+			->addParameters(vec['mixed $input', 'string $pointer'])
+			->setBody($hb->getCode())
+			->setReturnType($this->getType());
+	}
+
+	<<__Override>>
+	public function getType(): string {
+		if (Shapes::keyExists($this->typed_schema, 'hackEnum')) {
+			if ($this->typed_schema['generateHackEnum'] ?? false) {
+				return $this->typed_schema['hackEnum'];
+			}
+			return Str\format('\%s', $this->typed_schema['hackEnum']);
+		}
+
+		return 'string';
+	}
+
+	<<__Override>>
+	public function getTypeInfo(): Typing\Type {
+		if ($this->getType() === 'string') {
+			return Typing\TypeSystem::string();
+		}
+		// TODO: Type resolution for hackEnum
+		return Typing\TypeSystem::nonnull();
+	}
 }