Remove MOGKeepIndexed

While it can probably be useful it doesn't make sense to keep that
around while not having a MOGMapIndexed which would make more sense to
add given that MOGKeep (renamed to MOGMapDropNil) is just MOGMap
composed with MOGDropNil.

MogKit/MogTransformation.h

@@ -23,12 +23,6 @@ typedef MOGReducer *(^MOGTransformation) (MOGReducer *);
  */
 typedef id (^MOGMapBlock) (id val);
 
-/**
- * `MOGIndexedMapBlock` is the same as `MOGMapBlock`, only it also includes the index of the value in sequence
- * that is being processed.
- */
-typedef id (^MOGIndexedMapBlock) (NSUInteger index, id val);
-
 /**
  * `MOGPredicate` is a function that by examining the value returns YES or NO. It's typically used in `MOGFilter` or
  * `MOGMapDropNil`.
@@ -177,19 +171,6 @@ MOGTransformation MOGReplaceWithDefault(NSDictionary *replacements, id defaultVa
  */
 MOGTransformation MOGMapDropNil(MOGMapBlock mapBlock);
 
-/**
- * Creates a transformation that keeps values where `mapBlock` returns a non-nil value. This is similar to
- * `MOGMapDropNil` with the difference that the index of the value is passed to `mapBlock` as well.
- *
- * @param mapBlock a function that determines if the transformation should pass on a value or not. non-nil to pass on,
- *        nil to drop it.
- *
- * @return a stateful transformation that drops all values where `mapBlock` returns nil.
- *
- * @see `MOGFilter`, `MOGRemove` and `MOGKeep`.
- */
-MOGTransformation MOGKeepIndexed(MOGIndexedMapBlock mapBlock);
-
 /**
  * Creates a transformation that drops all duplicates. Whether it's a duplicate is determined by `isEqual:`
  *

MogKit/MogTransformation.m

@@ -132,17 +132,6 @@ MOGTransformation MOGMapDropNil(MOGMapBlock mapBlock) {
     return MOGCompose(MOGMap(mapBlock), MOGDropNil());
 }
 
-MOGTransformation MOGKeepIndexed(MOGIndexedMapBlock indexedMapBlock) {
-    return ^MOGReducer *(MOGReducer *reducer) {
-        __block NSUInteger index = 0;
-
-        return [MOGReducer stepReducerWithNextReducer:reducer reduceBlock:^(id acc, id val) {
-            id outValue = indexedMapBlock(index++, val);
-            return outValue != nil ? reducer.reduce(acc, outValue) : acc;
-        }];
-    };
-}
-
 MOGTransformation MOGUnique(void) {
     return ^MOGReducer *(MOGReducer *reducer) {
         NSMutableSet *seenValues = [NSMutableSet new];

MogKitTests/MogTransformationTests.m

@@ -248,18 +248,6 @@ - (void)testKeepTransformation
     XCTAssertEqualObjects(expected, result);
 }
 
-- (void)testKeepIndexedTransformation
-{
-    NSArray *array = @[@1, @2, @3, @4, @5, @6, @7, @8, @9, @10];
-    NSArray *expected = @[@21, @23, @25, @27, @29];
-
-    NSArray *result = MOGTransform(array, MOGArrayReducer(), MOGKeepIndexed(^id(NSUInteger index, NSNumber *number) {
-        return index % 2 == 0 ? @(number.intValue + 20) : nil;
-    }));
-
-    XCTAssertEqualObjects(expected, result);
-}
-
 - (void)testUniqueTransformation
 {
     NSArray *array = @[@1, @2, @3, @4, @3, @2, @1, @8, @9, @10];

README.md

@@ -127,7 +127,6 @@ The transformation can then be reused and is not even tied to `RACStream`.
 - Replace
 - ReplaceWithDefault
 - MapDropNil
-- KeepIndexed
 - Unique
 - Dedupe
 - Cat