Seq puts all your logs into a quick searchable system that allows you to easily track down bugs. I started using Seq with Serilog when I was working at my last company and it is amazing what a difference it can make having useful searchable logs. However, most of them aren’t particularly useful for tracking down errors and seeing how your service is performing. In this example, the sequence processing takes 18 steps instead of 23 steps for doing the same with lists.I have used quite a few logging frameworks in the past such as Log4Net and Splunk. When the result size reaches 4, the processing stops because it's the largest possible size that take(4) can return. Note that for elements left after filtering, the map executes before filtering the next element. So, you first see the line of text “Lengths of.” and then the sequence processing starts.
#STEP SEQ IP CODE#
The output of this code shows that the filter() and map() functions are called only when building the result list. terminal operation: obtaining the result as a List Println("Lengths of first 4 words longer than 3 chars") Val lengthsSequence = wordsSequence.filter Val words = "The quick brown fox jumps over the lazy dog".split(" ") The code below filters the words longer than three characters and prints the lengths of first four such words. IterableĪssume that you have a list of words. Let's take a look at the difference between Iterable and Sequence with an example. That is mentioned specifically in their documentation. Sequences can be iterated multiple times however some sequence implementations might constrain themselves to be iterated only once. Sequence elements can be retrieved only with terminal operations. Examples of terminal operations are toList() or sum(). If a sequence operation returns another sequence, which is produced lazily, it's called intermediate. Stateful operations require a significant amount of state, usually proportional to the number of elements in a sequence. Stateless operations can also require a small constant amount of state to process an element, for example, take() or drop(). Stateless operations require no state and process each element independently, for example, map() or filter(). The sequence operations can be classified into the following groups regarding their state requirements: To create a sequence, call the sequenceOf() function listing the elements as its arguments. Hence, you should consider both Sequence and Iterable and decide which one is better for your case. However, the lazy nature of sequences adds some overhead which may be significant when processing smaller collections or doing simpler computations. So, the sequences let you avoid building results of intermediate steps, therefore improving the performance of the whole collection processing chain. In turn, Iterable completes each step for the whole collection and then proceeds to the next step. The order of operations execution is different as well: Sequence performs all the processing steps one-by-one for every single element. In turn, multi-step processing of sequences is executed lazily when possible: actual computing happens only when the result of the whole processing chain is requested. The following step executes on this collection. When the processing of an Iterable includes multiple steps, they are executed eagerly: each processing step completes and returns its result – an intermediate collection. Sequences offer the same functions as Iterable but implement another approach to multi-step collection processing.
Along with collections, the Kotlin standard library contains another container type – sequences ( Sequence).
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