AWS CloudFormation Linter

Using `.deep` to compare `Array`s is deprecatedSC-W1051 Array comparison using conventional comparison operatorsSC-W1046 Invalid deprecated annotation usedSC-W1035 Duplicate `case` bodiesSC-W1036 Method parameter shadowedSC-W1037 Incorrect stringification of an `Array`SC-W1047 Use `.isNaN` to check if a `Double` is `NaN`SC-W1052 Use `==` or `!=` instead of `.equals(null)` to compare against `null`SC-W1053 `Try` values must be checked before calling `.get`SC-W1054 Builtin structure shadowed by user defined typeSC-W1055 Consider adding explicit type annotations to public membersSC-W1058 Initializing `StringBuilder` with a `Char` results in empty stringSC-W1060 Potential `NoSuchElementException` in accessing filtered elementsSC-R1006 Calling garbage collector manually does not necessarily improve performanceSC-P1008 Do not attempt to trap `IllegalMonitorStateException`SC-W1039 Use string interpolation to concatenate an entity to a stringSC-W1070 Audit: log4j version used could lead to remote code executionSC-A1003 Comparing a fresh object with the result of `getClass` always evaluates to `false`SC-W1071 Exception in `catch` clause is unreachableSC-W1072 Missing type parameter for cast operationsSC-W1075 `hashCode()` relies on a mutable valueSC-W1076 Method's generic parameter shadows class' generic parameterSC-W1078 Sealed entity has no descendantsSC-W1079 Equality methods overridden in a `case` classSC-W1074 Missing `catch` clause for `try`SC-W1081 `equals()` and `hashCode()` must be overridden in pairSC-W1073 Consider using `Symbol()` over deprecated symbol literal syntaxSC-W1080 Do not prefix enum members with enum's nameSC-R1085 Consider specifying type in `catch` clauseSC-W1089 Enum value has a member that maps to an already mapped valueSC-W1087 Annotating a method with both `inline` and `tailrec` annotations results in a compile-time error in future Scala versionsSC-W1088 Access modifiers `protected[this]` and `private[this]` are deprecatedSC-W1090 Use the `inline` keyword instead of the annotationSC-R1087 If-else chain has a duplicate conditionSC-W1086 `length`-like property is compared against values which always evaluate to the same resultSC-W1091 XML literals are deprecated and will be phased outSC-W1094 Misplaced `return` statement in a method of `Unit` return typeSC-W1095 Consider using ADTs instead of `scala.Enumeration` for `enum`-like featuresSC-W1093 Object created is neither assigned to a variable nor passed as an argument but is dropped immediatelySC-W1096 Use `summon[T]` over `implicitly[T]` in Scala 3 to probe for `implicit`-sSC-W1092 Methods returning `Option` should only return `Some` or `None`SC-T1005 Use `.lastOption` to access the last elementSC-P1001 Use `.isEmpty` or `.nonEmpty` to check if structure is emptySC-P1002 Consider filtering first and then sortingSC-P1003 Consider using the appropriate overloaded method when searching for a single charSC-P1004 Calling `List.size` is inefficientSC-P1005 Consider rewriting `filter().headOption` as `find()`SC-P1006 Appending to `List` is in-efficientSC-P1007 Consider combining successive `.filter()` callsSC-P1009 Use anonymous pattern-matching functions instead of match blocks within iteratorsSC-R1001 Consider using `.isEmpty` or `.nonEmpty` instead of `.size` for `List`sSC-R1025 Use pattern matching instead of repeated calls to `isInstanceOf`SC-R1029 Consider rewriting `.find().isDefined` as `.exists()`SC-R1033 Consider rewriting `.reverse.tail.reverse` as `.init`SC-R1035 Consider rewriting `.reverse.take().reverse` as `.takeRight()`SC-R1036 Consider rewriting `.filter().lastOption` as `.findLast()`SC-R1037 Duplicate key in `HashMap`SC-W1019 Pattern matching may be non-exhaustiveSC-W1024 Usage of reserved keywordsSC-W1030 Potential resource (file handle) leakSC-W1033 Variable shadows another variable with same name in the parent scopeSC-W1050 Avoid nested `match` expressionsSC-W1059 Consider using `flatten` to extract the required valuesSC-R1034 Consider using `sys.env.get` instead of `System.getenv` when accessing environmental variablesSC-R1044 `stripMargin` on a regular expression alters its behaviorSC-W1066 Consider making `case objects` `final`SC-W1067 Use of Yoda expressionsSC-W1068 `final` modifier is redundant for `object`SC-R1053 Consider explicitly defining the main method, i.e. the entry pointSC-W1062 Classes should not extend `java.lang.Error`SC-R1045 Exception thrown is genericSC-R1043 Consider using `AutoCloseable` for closing resourcesSC-R1052 Deprecated multiarg infix syntaxSC-R1041 Accessor like method has return type `Unit`SC-R1042 `finalize`rs should not be defined explicitlySC-R1046 Explicitly defined `finalize`rs should not be publicSC-R1047 `finalize`rs should call `super.finalize` for super classes to run their own finalization logicSC-R1048 Overridden methods cannot simply call `super`SC-R1049 Empty `finalize`rs do not add anything of value and are redundantSC-R1050 Consider dropping parentheses for accessor like methodsSC-R1051 Consider using `.reduceOption` over `.reduce`SC-R1054 SBT: Consider using the `slash` syntax instead of `in`SC-W1064 Tests should have `assert` statementsSC-W1065 Sealed `trait`s descendants must be `final`SC-W1069 Accessing internal APIs via `--add-exports`SC-W1063 Exception is generalized in the catch clauseSC-R1055 Lambda can be converted to expression bodied lambdaSC-R1063 Specifying the default value for an `implicit` parameter may adversely affect readabilitySC-R1059 Variable can be declared as a `val` instead of `var`SC-R1061 Using of braces in `import` statements is discouraged if importing a single entitySC-R1060 Empty `finally` blockSC-R1056 Catch clauses should do more than just rethrow exceptionsSC-R1057 Pure methods should not have side-effectsSC-R1058 Unary operator is redundant due to its operandSC-R1064 Consider using `uninitialized` instead of `_` for uninitialized fields in Scala 3SC-R1078 Parameters with default values should always be specified at lastSC-R1074 Unary methods should not have any parentheses/take any argumentsSC-R1079 Consider using the new syntax for vararg splicingSC-R1080 Consider using the `as` keyword for import aliasesSC-R1081 Consider returning values from `if` statement where possibleSC-R1082 Pattern matching only mentions wildcard patternsSC-R1066 Lambda parameter is unusedSC-W1083 Universal `apply` methods make the `new` keyword redundantSC-R1069 Unary methods cannot have return type `Unit`SC-R1083 Consider using `implicit` over view boundsSC-R1065 Exception variable is declared but unusedSC-W1082 Consider breaking down long literals using the underscore tokenSC-R1084 An entity that was already imported was re-importedSC-R1071 Consider using `?` for wildcard arguments in types instead of `_` in Scala 3SC-R1077 Consider using `*` for wildcard imports instead of `_` in Scala 3SC-R1075 Range's upper bound is equal to a length-like propertySC-W1084 Exception is instantiated using `new` but is not thrownSC-W1085 Classes that are not exceptions should not end with `Exception`SC-R1072 Classes that do not receive any parameters should not define empty parameter listSC-R1073 Fold expression used to sum elements can be simplifiedSC-R1067 Consider using the `@targetName()` annotation for symbol-like methodsSC-R1068 Using the logical not operator to invert binary expressions can affect readabilitySC-R1070 Import aliases do not need to be wrapped in braces in Scala 3SC-R1076 Audit required: Instance of `NotImplementedError`SC-A1005 `infix` modifier is redundant for symbol-like methodsSC-R1089 Consider using `.findLast()` over `.reverse.find()`SC-P1012 Use prefix notation over postfix notation where possibleSC-R1090 Consider turning partial function into anonymous functionSC-R1093 Consider using the efficient alternative `.reverseIterator` over `.reverse.iterator`SC-P1010 Consider using `.collectFirst()` over `.collect().headOption`SC-P1011 Consider using `Option(...)` instead of an explicit `if` statementSC-R1092 Consider using `None` instead of `Some(null)`SC-A1002 Consider grouping imports from same package togetherSC-R1011 Consider using the comparison operators `==` or `!=` to compare `String`sSC-R1026 Consider using `.dropRight` instead of `.substring` when the lower-bound is 0SC-R1027 Redundant `val` keyword for case class' constructor parameterSC-R1038 Consider simplifying `if`-`else` when returning only `Boolean` valuesSC-R1040 Missing package declaration for fileSC-W1045 Consider dropping pointless type boundsSC-R1032 Use of `TODO/FIXME` comment encounteredSC-D1000 `if` condition can be moved inside the `for` loop as an enumerator guardSC-R1062 Redundant brace initializer when instantiating objectSC-R1086 Wrapping identifiers in braces in interpolation is redundantSC-R1088 Empty interpolated stringSC-W1011 Incorrect number of args to String.formatSC-W1008 Missing case `None` in pattern-matchingSC-W1025 Infix operator has same operand on both sidesSC-W1026 Duplicated `then` and `else` blocksSC-W1027 Type `T` is a potential candidate for type erasureSC-A1004 Catching of ThrowableSC-W1010 Detected unreachable codeSC-W1006 Duplicate case in pattern-matchingSC-W1007 Oddness check i % 2 == 0 fails for -ve numbersSC-W1000 Missing method return typeSC-W1009 Explicit trap of `NullPointerException`SC-W1021 `If` condition depends on `boolean` value that is a compile time constantSC-W1022 Unused method parameterSC-W1038 Audit required: Insecure hash functionSC-A1001 Explicitly casting an object via `.asInstanceOf`SC-T1000 Explicit cast operation: `isInstanceOf`SC-T1001 Method has return type `Any`SC-T1002 Consider making this `case` class finalSC-W1001 Exception caught is genericSC-W1005 Variable assigned to itselfSC-W1014 Case class should always take a parameterSC-W1077 Usage of wildcard importsSC-C1001 Exception naming does not follow the recommended styleSC-C1000 Replace `find() [==/!=] None` with `exists()`SC-R1009 Methods with single statement in body may follow single-line conventionSC-C1006 Too many method parametersSC-C1002 Prefer using `Option.isDefined`, `Option.isEmpty` or `Option.nonEmpty` instead of `Option.size`SC-R1004 Redundant `getOrElse()` on `get()`SC-R1005 Replace `filter().isEmpty` with `!exists()`SC-R1007 Replace `filter().size` with `count()`SC-R1008 Parameterless method has return type - UnitSC-R1014 Redundant `else` in `else if`SC-R1015 Use 'until n' instead of 'to n - 1' in loopsSC-R1016 Replace `!isEmpty` with `nonEmpty`SC-R1017 Replace `!nonEmpty` with `isEmpty`SC-R1018 Simplify verbose boolean comparisonSC-R1020 Prefer using `.get` and then pattern matching over `.contains` for a MapSC-R1021 Consider using `.isEmpty` or `.nonEmpty` when checking for empty `String`sSC-R1022 Consider rewriting this `if` condition as case's entry guardSC-R1023 Prefer `String` interpolation over `String.format`SC-R1030 Duplicate element in `HashSet`SC-W1020 Redundant `return` keyword for the last expression of the blockSC-W1029 Use pattern matching instead of calling `.get` on `Option`SC-W1049 Empty statements blockSC-C1004 Structure is missing mutability-prefixSC-R1010 Explicit `null` in value assignmentSC-W1012 Explicit `null` in method callSC-W1013 Method variant that return `Option[T]` should have their names suffixed with `Option`SC-C1005 Function with cyclomatic complexity higher than thresholdSC-R1091

SC-R1067

Fold expression used to sum elements can be simplifiedSC-R1067

Major

Anti-pattern

The fold methods such as fold, foldLeft, and foldRight process elements in an order specific to each of these variants. These methods take in an initial value to which the computed sum is added to. Setting the initial value to 0 and simply adding the elements using the infix operator + is equivalent to adding all the elements in the iterable. In such cases, consider using the .sum method instead.

Bad Practice

val sum = elems.foldLeft(0)(_ + _)

Recommended

val sum = elems.sum