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    Home Unlabelled Lisp Programmers: Is there actual use of Lisp in industry? How do you use it at your work? How do you overcome the "Lisp quirks"? Ask Programming

    Lisp Programmers: Is there actual use of Lisp in industry? How do you use it at your work? How do you overcome the "Lisp quirks"? Ask Programming

    August 02, 2019

    Lisp Programmers: Is there actual use of Lisp in industry? How do you use it at your work? How do you overcome the "Lisp quirks"? Ask Programming

    Lisp Programmers: Is there actual use of Lisp in industry? How do you use it at your work? How do you overcome the "Lisp quirks"?

    Posted: 02 Aug 2019 04:25 PM PDT

    Hi all

    I'm mainly a Python programmer but also know a little C. After diving a bit into Scheme (a dialect of Lisp), I found that: - the monotone syntax are source of a lot of bugs and confusion (like parentheses, quoting, knowing what expression is evaluated, etc) - the almost typeless design makes introducing type mistakes very easy - the little to no distinction between code and data can be a security threat

    I think Lisp is an interesting concept but I can't see how it can be used effectively in the real world.

    Do you use a dialect of Lisp (Clojure, Common Lisp, Scheme, etc) at your work? What do you use it for? How do you overcome these issues (or I guess features if you use it properly) listed above (and perhaps more)?

    submitted by /u/sammdu
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    As a beginner, would learning a functional programming language first make you a better programmer when learning a "traditional" language like C?

    Posted: 02 Aug 2019 12:38 PM PDT

    Python - regex giving unwanted results when converting between text formats

    Posted: 02 Aug 2019 05:28 PM PDT

    I have text in a certain website's format and need to convert it to LaTeX with Python. For example:

    Charles Dickes wrote ~A Tale of Two Cities~ and ~David Copperfield~.

    needs to turn into

    Charles Dickens wrote \\textit{A Tale of Two Cities} and \\textit{David Copperfield}.

    My regex looks like this:

    re.sub('\~([^_]*)\~','\\\\textit{\\1}', 'T Charles Dickes wrote ~A Tale of Two Cities~ and ~David Copperfield~.')

    This doesn't work, though. It turns into this:

    Charles Dickens wrote \\textit{A Tale of Two Cities~ and ~David Copperfield}.

    Why is this? Also, I hate this regex wizardry and would find it much easier I think to parse by char, but my understanding is that this is bad practice and that regex is optimized for much better speed than manual parsing?

    submitted by /u/VerySecretCactus
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    Any chance a HackerRank interview hiring test question could be unsolvable?

    Posted: 02 Aug 2019 08:22 PM PDT

    Long story short, I've applied to a good company and I have to do a test on Hackerrank. In one of the algorithms, they say the answer can only be X, Y, or Z. I've gotten several cases to pass with my own code and was really stumped because I had no idea why so many were failing. I decided to work backward and put X, Y, and Z as my return statements and sure enough hardly any of them pass. When reviewing the answers there are no failures do to time restrictions either, so it leads me to believe that some of the cases are just unsolvable. Does anyone know if this could be the case?

    submitted by /u/bikesarebomb
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    High Performance JDBC Connection Pooling with Oracle Database

    Posted: 02 Aug 2019 07:20 PM PDT

    TL;DR:

    I'm an Oracle performance engineer concerned about connections storms on a very high-concurrency system with low latency requirements. I believe much of the system instability is due to an extremely rapid increase of connections stemming from a large difference in MIN and MAX connections configured in the JDBC (UCP) connection pools. I believe I need material on the danger of large, dynamic connection pools with high-performance databases caused by connection storms resulting from traffic volume changes and brief database latches/serializations. Oracle makes this clear, but I need persuasive information for developers and middle-tier folks on this topic from well-known, respected, and/or trusted authors or resources in the (Java) development community.

    Background context if you are interested or like to read:

    Hello, I am a lead Oracle Performance Engineer for a very large financial institution, and I need some help from some knowledgeable Java developers. I'm looking for some expertise or assistance on the topic of configuring JDBC connection pools (specifically UCP if it matters) for a very high-concurrency, very low-latency OLTP application running against an Exadata Oracle RAC database (12.1.0.2).

    My understanding/perception is that developers and middle-tier engineers are often taught that connection pools should be dynamic in size (number of connections) to be scalable. This logic makes perfect sense to me. The only problem is that from a database performance perspective (at least for Oracle), large dynamic connection pools are very dangerous. In fact, for decades, Oracle's top performance experts (including their Real World Performance group) have said that most of the performance issues on which they are consulted have issues with the connection pool configuration, and that they spend much of their time explaining why large, dynamic connection pools, perhaps counter-intuitively, make the entire system less stable and more prone to "connection storms" and perceived timeouts/delays in query latency.

    The reason for this is pretty straightforward from an Oracle DB perspective: establishing a new connection is one of the single most expensive (resource-intensive) operations for the database server and software. The reason is complex, but basically each new connection requires a fairly large amount of CPU, memory allocation, and internal latching to establish the session state required for the new connection (this all presumes Dedicated Server mode, not Shared). A new server process is forked for the session, memory is allocated for the session, much recursive (background) SQL is executed (and often requires parsing), latches are held briefly, etc.

    The problem with large, dynamic connection pools when combined with very high-volume/concurrency databases is that, while most establish a relatively conservative INITIAL/MINIMUM number of connections, they often leave the MAXIMUM number of connections very high (or unlimited in some cases). I'm not sure if this is due to industry best practice, training, or the bias of almost every example of how to configure a connection pool in documentation and online, but I digress). Relational databases like Oracle have some operations that are inherently "serialized" or blocking. Over the last few releases, many or most changes have been made non-blocking, including as much DDL as possible. The problem is that almost anything else that causes some increased contention (a background job which cleans up orphaned entries in indexes, gathering daily optimizer statistics, creation of a new daily partition on a heavily inserted table, index contention, etc.) There are known workarounds for some of these issues, but not all, and even the workarounds move us away from automation and availability and back to requiring an outage for some maintenance and reverting to more labor-intensive and error-prone manual processes (manual drops of partitions and index rebuilds, pre-creation of partitions, gathering of stats offline or estimating them manually). Most of these things can be easily tolerated by most applications.

    However, since traffic is based on human activity (transactions), the workload ebbs and flows (like most OLTP system workloads) and doesn't slow down for DB events! However, once we hit any number of known (or still to be determined) causes of very brief database serialization (required for consistency, durability, maintenance, etc.) will cause a very brief delay to many or all of the currently INSERTing DML records. Maybe stats causes contention, or invalidates the query requiring a hard reparse, or extents/space in a new partition need to be allocated, etc. The problem is, by t+1 second there are many hundreds of active sessions in the database (Oracle's activity-over-time data is captured once per second). By t+2 second there may be hundreds more. Then the database essentially runs like molasses, timing out all queries beyond their 3 second SLA, for between 1 and 8-9 minutes. This is a VERY bad problem for the business (another organization processes the records as "stand-in", but we pay dearly). To the developers and middle-tier folks there is no other alternative but DB tuning. They reason that since the traffic coming into the system doesn't slow, the application server shouldn't throttle it in any way. The question is when does not throttling cause a part of the system (the database) to become the performance bottleneck?

    I believe the primary reason the system as a whole is so volatile and sensitive is that the connection pool treats the database as if more simultaneous work will deliver faster overall results, which is backwards. In fact, it's rather amazing the DB can recover from the added stress of the new connections being ramped up at high velocity (using CPU, latches, parse locks, and memory allocation), especially when all the sessions begin to wait on the same thing.

    My question is, how do I convince skeptical Java developers and middle-tier folks that this is worth investigating? I have much literature from Oracle and various Oracle performance experts to document and even demonstrate the problem, and actually recommend a static pool configuration (MIN=MAX), as long as the min is set high enough. Basically the DB gets massively overloaded and as a result performance spirals downhill until the DB & host somehow get through the wall of connections thrown at the database. I am well-respected in the organization, but I'm having peculiar trouble convincing this team to consider how they configure their connection pools. They have many small pools with a MIN of ~5 and a max of over 100 on each of the hundreds of app servers on JVMs. I realize having a static pool may be impossible when you use your app servers to spread the load like this, but there is even a product from Oracle called "Database Resident Connection Pool." It was originally designed for connections that didn't have access to their own pool (like Java), but recent versions include JDBC/UCP enabled pools. I believe I need to find recognized experts or resources in the developer or middle-tier circles that give this advice (at least for Oracle databases) or explain the dangers of overloading the database with connection storms.

    submitted by /u/gkoerk
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    Utterly stuck, one hurdle from completing University

    Posted: 02 Aug 2019 06:39 PM PDT

    I'm completely stuck on a project involving JavaSpace (Apache River). The idea is to create some kind of object-based auction site (Items, Descriptions etc) with basic functionality. The basic idea is in my mind but I can't find the right way to start. Any documentation I find seems to be all or nothing with no steps on how to get from A to B.

    Do you have any suggestions in how to proceed with this kind of task, or some advice on where I could find appropriate tutorials or documentation. Suffice to say my Lecturer has been less than helpful in this regard so far.

    submitted by /u/BrokenNorthern
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    Whats this asking?

    Posted: 02 Aug 2019 06:17 PM PDT

    Code a class encapsulating a stack of clothes using an array. A clothing item has the following attributes: names, color, and whether it can be washed at high temperature. Limit your stack to 20 clothing items. In addition to creating your push, pop, and peek methods; create two additional methods: a method that return all of the clothing items of a given color; a method that returns how many clothing items in the stack can be washed at high temperature. Write a program to test your stack with all these methods.

    Looking up what ecapsulating is, so I make a a class for the clothes using getters and setters. Simple enough, but the rest of it I dont understand. do I make 20 objects of clothes and store it in the array?

    my class lecture on stacks was literally only this

    https://imgur.com/a/wTVD0Ok

    and we're not even c# we're java rofl

    submitted by /u/blacklegzoroo
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    Java to Python

    Posted: 02 Aug 2019 02:00 AM PDT

    I have been coding in Java for the past 4 years in high school and need to learn Python for college because my college courses will be taught in Python.

    I have a pretty strong grasp of most concepts in Java (strings, arrays, Objects, recursion, iterative loops, algorithms, data structures). In college, however, all my introductory courses are in Python. So I need to start coding in python before college starts. Where and how should I learn Python?

    submitted by /u/pikada_memesonmolly
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    How would you recreate this testimonial using CSS Grid?

    Posted: 02 Aug 2019 04:36 PM PDT

    <style> .container { border: 2px solid #ccc; background-color: #eee; border-radius: 5px; padding: 16px; margin: 16px 0; } .container::after { content: ""; clear: both; display: table; } .container img { float: left; margin-right: 20px; border-radius: 50%; } .container span { font-size: 20px; margin-right: 15px; } </style> <div class="container"> <img src="bandmember.jpg" alt="Avatar" style="width:90px"> <p><span>Chris Fox.</span> CEO at Mighty Schools.</p> <p>John Doe saved us from a web disaster.</p> </div> <div class="container"> <img src="avatar_g2.jpg" alt="Avatar" style="width:90px"> <p><span >Rebecca Flex.</span> CEO at Company.</p> <p>No one is better than John Doe.</p> </div>
    submitted by /u/sea_place
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    Python Boolean Values

    Posted: 02 Aug 2019 04:20 PM PDT

    I'm creating a simple program but I dont understand the logic of these statements.

    start = input("Push enter to start ")

    print(start == True)

    print(start == False)

    >False

    >False

    How can a statement be neither true or false?

    submitted by /u/beefbrisket99
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    Is it well defined behaviour to "override" a (custom) CMake function via include files?

    Posted: 02 Aug 2019 09:44 AM PDT

    I have a Platform.cmake which defines some "abstract" functions (which just log that the function isn't implemented), then detects the target platform, and includes one of various CMake files for each supported platform, which basically redefine those functions with specific implementations.

    I can't find much documentation on whether this is supported or might break in a future release?

    submitted by /u/ludonarrator
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    I'm trying to learn to build a website template using CSS Grid, can you tell me why my header isn't filling in its container?

    Posted: 02 Aug 2019 07:27 AM PDT

    The width of the container holding everything is 60% and I want the header item to take up the entire width available so that the gray background extends sideways to the edge of the container.

    <html> <head> <style> * {margin: 0; padding: 0;} html {display: grid; grid-template-columns: 60%; justify-content: center;} body {display: grid; grid-template-columns: repeat(2, 1fr); grid-template-rows: repeat(4, auto); justify-items: center; grid-template-areas: "header header" "main main" "left right" "footer footer";} header {background: gray; grid-area: header; display: grid; grid-template-columns: 100%; justify-items: stretch;} main {background: red; grid-area: main;} .left {background: green; grid-area: left;} .right {background: blue; grid-area: right;} footer {background: gray; grid-area: footer;} </style> </head> <body> <header>header</header> <main>main</main> <section class="left">left</section> <section class="right">right</section> <footer>footer</footer> </body> </html>
    submitted by /u/sea_place
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    Is my assumption wrong about two algorithms or simply my approach?

    Posted: 02 Aug 2019 01:12 PM PDT

    I was asked to compare solution and "real clock time" between forward dijikstra's algorithm (shortest path algorithm) and bidirectional algorithm (dijikstra's forward and back combined). It was my understanding bidirectional would be more efficient/faster. But we were asked to use real clock time to compare efficiency. And upon doing so, both of my measurements took 0.0 seconds to process the results. I assumed this was normal, as my machine computes very quickly. Given the same data set, should I expect actual difference in real time clock? Should I be measuring in smaller units (nano/mili seconds)? Or should I convince the assignee to allow me to measure time using processing/CPU units?

    submitted by /u/disposable202
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    [C#] Json Serialization

    Posted: 02 Aug 2019 12:58 PM PDT

    I am trying to load a file by using Json deserialization. I have a super Dot, which several other classes, Itm, Cha, Fac for examples, that use Dot as a base class. I want to be able to use one method to load the text to deserialize and to create a class object of the appropriate type, based on knowing the three-letter class name.

    The part I am having trouble with is creating an object of a specific class.

    For example, the following is what I want to do, but does not work. In this example, I have received text "Itm1201", which is the value of the parameter "ID" in an "Itm" class object. For example, I may type this into a text box, and then have it load the file with name "Itm1201" to my display interface.

    string ClassIdentifier = "Itm1201".Substring(0,3); // ClassIdentifier now is "Itm", the name of the class.

    ( Type.GetType(ClassIdentifier) ) NewObjectOfVariousPossibleClasses = Dot.LoadFile("Itm1201"); //LoadFile is able to find the appropriate file that it needs to load. The problem here is getting the NewObjectOfVariousPossibleClasses to be created as the appropriate type, since if I try to simply assign it as a Dot object, I cannot cast it down into its lower class type.

    NewObjectOfVariousPossibleClasses.ID = "Itm1202" //Be able to use this new variable as if it were a "Dot" type, since all of the Dot derivative classes have similar methods and variables, except a few.

    ​

    Sorry if I make it hard to understand, I have a feeling that my design is inherantly flawed, but I'm not that experienced so I'm not sure where I'm going wrong. I could just have methods for each of the classes, but that means that for every derivative class, I will need to implement the LoadFile method in the interface, instead of being able to have one method that is able to tell which version I need.

    submitted by /u/Retroroid
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    This is kind of a dumb question, but how does javascript not get the "number" confused?

    Posted: 02 Aug 2019 09:02 AM PDT

    I'm using the same variable, "number" twice, but Javascript parses it correctly. 

    numbers = [ {number: 1}, {number: 5}, {number: 8}, {number: 9}, {number: 13}, ] for (let number of numbers) { if (number.number === 9) { number.number = 900; } }
    submitted by /u/mementomoriok
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    What are your biggest everyday struggles?

    Posted: 02 Aug 2019 11:56 AM PDT

    Hey guys, ~mid front-end developer here, also interested in self-development. I'm thinking about starting a blog and consulting and I'm doing research on some topics - one of those are the problems of everyday developers. Hope you could help me with some input.

    1. As a programmer, what are the 2 biggest personal issues you're dealing with? I don't mean outer stuff like stack, annoying bosses, meetings etc. I mean inner stuff like procrastination, time management, motivation, social anxiety, etc. Also what is your exact profession?
    2. Regarding your wellbeing, what would you wish for more than anything else?
    submitted by /u/Faber91pl
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    LAMP, php and bash

    Posted: 02 Aug 2019 11:51 AM PDT

    I know PHP,and python are used commonly in a LAMP stack. Why isn't something like bash or any other language used?

    What makes PHP different from BASH SCRIPTS in this case?

    submitted by /u/ucvb_ucvb
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    Android app in JS

    Posted: 02 Aug 2019 09:32 AM PDT

    Can I make an Android application frontend in JS? And how useful is knowledge of JS while developing an Android application?

    submitted by /u/nblogist
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    Graduated from community college & Feel more lost than when I started.

    Posted: 01 Aug 2019 11:24 PM PDT

    I graduated from Jackson State Community College in December 2017, started working at a job where I was promised to get web design experience (still hasn't happened), got married, and bought a house. I'm wondering if I've messed up.

    In college I learned: HTML, CSS, C++, MySQL, and a little Java. They showed us what web and software development looks like, and what networking looks like. I kept all of those languages in practice for about six months, then lost hope. The little experience I received from the job was create an "email safe website". It was a BAD HTML with inline CSS project. I HATED that project. Since then, I've watched soooooo many videos about Wordpress that I think I'm growing hatred towards it.

    I believe I want to go into Web programming at this point, since that's where I have the most experience, but I'm not sure. I'm starting to work on some Javascript courses, and I feel extremely overwhelmed by what I don't know. I figured I should learn enough to try for a Junior Web Developer job somewhere. I can't find ANY programming jobs in Jackson, TN as of this post.

    Should I consider moving or is there some kind of work where I can work from home? I'm 22 and I have no mentor to talk with, so I appreciate any honest advice or suggestions. I'm so impressed by what I see you all do, and I want to be a part of it. Thank you for your time and knowledge!

    submitted by /u/WheepingSoldier
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    Code Reviews

    Posted: 02 Aug 2019 08:44 AM PDT

    Got a python script I wrote for DevOps project. It uses Boto3 library to collect info on aws resources, I was wondering is there a community or place I can put my code on for people to review ?

    It's not the most efficient code out there and I'd like some comments on it ! Any suggestions ?

    submitted by /u/bigEd392
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    Is there a good way to share small amounts of data between 2 or more processes?

    Posted: 02 Aug 2019 04:33 AM PDT

    So I'm working the first time with dart and tried to make a little project,
    for that I have a backend, written in nodeJs and a web-crawler where i wanted
    to use Dart.
    Now i need to share small amounts of data between them (something like how long the crawler runs).

    So I was wondering if there is anything like SQL just for small amounts data.

    submitted by /u/Comesa
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    What is the best library for parsing and generating EDI X12?

    Posted: 02 Aug 2019 04:15 AM PDT

    I'm looking for a good library for parsing and generating EDI X12 (HIPPA) files (837, 834, 835...). Language doesn't really matter at this point. Thanks!

    submitted by /u/beer_kimono
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    My caret IDE for chromebook shows red "x" marks by the line number when it thinks I've made a mistake. What is this feature called and how do I disable it?

    Posted: 02 Aug 2019 05:55 AM PDT

    How do I plug in/implement a Python script for MacOS iBooks?

    Posted: 02 Aug 2019 05:36 AM PDT

    I'd like to make a personal script for iBooks where all the text I've highlighted in a certain book goes to an Excel spreadsheet. In essence, iBooks stores all of a book's user-highlighted phrases in a sidebar. I'm imagining a Python script that would scrape this sidebar and then copy all of the information into a spreadsheet, with each row being a different highlighted phrase, and each column constituting a unique piece of information about the highlighted phrase (ie page number, chapter title, etc.)

    I'm a newcomer to implementing programming, though, and I'm not quite sure where or how to start the process. Once I have written a Python script, how would I plug in/implement the code? Any tips/advice would be appreciated.

    submitted by /u/billybumpkins
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