Search Results

Search found 7380 results on 296 pages for 'scripting languages'.

Page 12/296 | < Previous Page | 8 9 10 11 12 13 14 15 16 17 18 19  | Next Page >

  • Functional programming constructs in non-functional programming languages

    - by Giorgio
    This question has been going through my mind quite a lot lately and since I haven't found a convincing answer to it I would like to know if other users of this site have thought about it as well. In the recent years, even though OOP is still the most popular programming paradigm, functional programming is getting a lot of attention. I have only used OOP languages for my work (C++ and Java) but I am trying to learn some FP in my free time because I find it very interesting. So, I started learning Haskell three years ago and Scala last summer. I plan to learn some SML and Caml as well, and to brush up my (little) knowledge of Scheme. Well, a lot of plans (too ambitious?) but I hope I will find the time to learn at least the basics of FP during the next few years. What is important for me is how functional programming works and how / whether I can use it for some real projects. I have already developed small tools in Haskell. In spite of my strong interest for FP, I find it difficult to understand why functional programming constructs are being added to languages like C#, Java, C++, and so on. As a developer interested in FP, I find it more natural to use, say, Scala or Haskell, instead of waiting for the next FP feature to be added to my favourite non-FP language. In other words, why would I want to have only some FP in my originally non-FP language instead of looking for a language that has a better support for FP? For example, why should I be interested to have lambdas in Java if I can switch to Scala where I have much more FP concepts and access all the Java libraries anyway? Similarly: why do some FP in C# instead of using F# (to my knowledge, C# and F# can work together)? Java was designed to be OO. Fine. I can do OOP in Java (and I would like to keep using Java in that way). Scala was designed to support OOP + FP. Fine: I can use a mix of OOP and FP in Scala. Haskell was designed for FP: I can do FP in Haskell. If I need to tune the performance of a particular module, I can interface Haskell with some external routines in C. But why would I want to do OOP with just some basic FP in Java? So, my main point is: why are non-functional programming languages being extended with some functional concept? Shouldn't it be more comfortable (interesting, exciting, productive) to program in a language that has been designed from the very beginning to be functional or multi-paradigm? Don't different programming paradigms integrate better in a language that was designed for it than in a language in which one paradigm was only added later? The first explanation I could think of is that, since FP is a new concept (it isn't new at all, but it is new for many developers), it needs to be introduced gradually. However, I remember my switch from imperative to OOP: when I started to program in C++ (coming from Pascal and C) I really had to rethink the way in which I was coding, and to do it pretty fast. It was not gradual. So, this does not seem to be a good explanation to me. Also, I asked myself if my impression is just plainly wrong due to lack of knowledge. E.g., do C# and C++11 support FP as extensively as, say, Scala or Caml do? In this case, my question would be simply non-existent. Or can it be that many non-FP programmers are not really interested in using functional programming, but they find it practically convenient to adopt certain FP-idioms in their non-FP language? IMPORTANT NOTE Just in case (because I have seen several language wars on this site): I mentioned the languages I know better, this question is in no way meant to start comparisons between different programming languages to decide which is better / worse. Also, I am not interested in a comparison of OOP versus FP (pros and cons). The point I am interested in is to understand why FP is being introduced one bit at a time into existing languages that were not designed for it even though there exist languages that were / are specifically designed to support FP.

    Read the article

  • Misconceptions about purely functional languages?

    - by Giorgio
    I often encounter the following statements / arguments: Pure functional programming languages do not allow side effects (and are therefore of little use in practice because any useful program does have side effects, e.g. when it interacts with the external world). Pure functional programming languages do not allow to write a program that maintains state (which makes programming very awkward because in many application you do need state). I am not an expert in functional languages but here is what I have understood about these topics until now. Regarding point 1, you can interact with the environment in purely functional languages but you have to explicitly mark the code (functions) that introduces them (e.g. in Haskell by means of monadic types). Also, AFAIK computing by side effects (destructively updating data) should also be possible (using monadic types?) but is not the preferred way of working. Regarding point 2, AFAIK you can represent state by threading values through several computation steps (in Haskell, again, using monadic types) but I have no practical experience doing this and my understanding is rather vague. So, are the two statements above correct in any sense or are they just misconceptions about purely functional languages? If they are misconceptions, how did they come about? Could you write a (possibly small) code snippet illustrating the Haskell idiomatic way to (1) implement side effects and (2) implement a computation with state?

    Read the article

  • Are dynamic languages at disadvantage for agile development?

    - by Gerenuk
    From what I've read agile development often involves refactoring or reverse engineering code into diagrams. Of course there is much more than that, but if we consider the practices that rely on these two methods, are dynamically typed languages at disadvantage? It seem static typing would make refactoring and reverse engineering much easier? Refactoring or (automated) reverse engineering is hard if not impossible in dynamically typed languages? What does real world projects tell about usage of dynamically typed languages for agile methodology?

    Read the article

  • UNIX Shell-scripting: UDV

    - by Myx
    I am writing a simple unix shell script: #!/bin/bash # abort the script if a command fails set -e # abort the script if an unitialized shell variable is used set -u i = 0; while [$i -l 1] do src/meshpro input/martini.off video/noise/image$i.off -noise $i src/meshview video/noise/image$i.off -output_image video/noise/image$i.jpg -exit_immediately i='expr $i + 0.1' done When I try to run the script, I get the following error: line 14: i: command not found. I used a tutorial to apply to my code. Any suggestions on what I'm doing wrong?

    Read the article

  • idioms for returning multiple values in shell scripting

    - by Wang
    Are there any idioms for returning multiple values from a bash function within a script? http://tldp.org/LDP/abs/html/assortedtips.html describes how to echo multiple values and process the results (e.g., example 35-17), but that gets tricky if some of the returned values are strings with spaces in. A more structured way to return would be to assign to global variables, like foo () { FOO_RV1="bob" FOO_RV2="bill" } foo echo "foo returned ${FOO_RV1} and ${FOO_RV2}" I realize that if I need re-entrancy in a shell script I'm probably doing it wrong, but I still feel very uncomfortable throwing global variables around just to hold return values. Is there a better way? I would prefer portability, but it's probably not a real limitation if I have to specify #!/bin/bash.

    Read the article

  • AWK scripting :How to remove Field separator using awk

    - by anil-1985
    Need the following output ONGC044 ONGC043 ONGC042 ONGC041 ONGC046 ONGC047 from this input Medium Label Medium ID Free Blocks =============================================================================== [ONGC044] ECCPRDDB_FS_43 ac100076:4aed9b39:44f0:0001 195311616 [ONGC043] ECCPRDDB_FS_42 ac100076:4aed9b1d:44e8:0001 195311616 [ONGC042] ECCPRDDB_FS_41 ac100076:4aed9af4:4469:0001 195311616 [ONGC041] ECCPRDDB_FS_40 ac100076:4aed9ad3:445e:0001 195311616 [ONGC046] ECCPRDDB_FS_44 ac100076:4aedd04a:68c6:0001 195311616 [ONGC047] ECCPRDDB_FS_45 ac100076:4aedd4a0:6bf5:0001 195311616

    Read the article

  • shell scripting: search/replace & check file exist

    - by johndashen
    I have a perl script (or any executable) E which will take a file foo.xml and write a file foo.txt. I use a Beowulf cluster to run E for a large number of XML files, but I'd like to write a simple job server script in shell (bash) which doesn't overwrite existing txt files. I'm currently doing something like #!/bin/sh PATTERN="[A-Z]*0[1-2][a-j]"; # this matches foo in all cases todo=`ls *.xml | grep $PATTERN -o`; isdone=`ls *.txt | grep $PATTERN -o`; whatsleft=todo - isdone; # what's the unix magic? #tack on the .xml prefix with sed or something #and then call the job server; jobserve E "$whatsleft"; and then I don't know how to get the difference between $todo and $isdone. I'd prefer using sort/uniq to something like a for loop with grep inside, but I'm not sure how to do it (pipes? temporary files?) As a bonus question, is there a way to do lookahead search in bash grep? To clarify: so the simplest way to do what i'm asking is (in pseudocode) for i in `/bin/ls *.xml` do replace xml suffix with txt if [that file exists] add to whatsleft list end done

    Read the article

  • Blackberry development on scripting language ?

    - by zvr
    From what I've seen, the preferred way to develop Blackberry applications is Java. Is this the only way? I'm dreaming of a rapid application environment where you can create GUIs (using the Blackberry UI components). Something like a port of Tcl/Tk on Blackberry... or Python/Tkinter... or something new, but similar. Does something like that exist ? (I doubt it) Can something like that exist ? (i.e., given the money, is it feasible/reasonable/...)

    Read the article

  • FTP to SFTP in shell scripting

    - by Kimi
    This script is to connect to different servers and copy a file from a loaction defined. It is mandatory to use sftp and not ftp. #!/usr/bin/ksh -xvf Detail="jyotibo|snv4915|/tlmusr1/tlm/rt/jyotibo/JyotiBo/ jyotibo|snv4915|/tlmusr1/tlm/rt/jyotibo/JyotiBo/" password=Unix11! c_filename=import.log localpath1=`pwd` for i in $Detail do echo $i UserName=`echo $i | cut -d'|' -f1` echo $UserName remotehost=`echo $i | cut -d'|' -f2` echo $remotehost remote_path=`echo $i | cut -d'|' -f3` echo $remote_path { echo "open $remotehost user $UserName $password lcd $localpath1 cd $remote_path bi prompt mget $c_filename prompt " } |ftp -i -n -v 2>&1 done I want to do the similar thing using sftp instead of ftp.

    Read the article

  • bash/ksh/scripting eval subshell quotes

    - by jhon
    Hi tehere, I'm using ksh and have some little troubles, could you help me? why does not this code run? [root]$ CMD="ls -ltr" [root]$ eval "W=$( $CMD )" [root]$ ksh: ls -ltr: not found. [root]$ echo $W and this works fine: [root]$ CMD="ls -ltr" [root]$ eval 'W=$('$CMD')' [root]$ echo $W Thanks :-)

    Read the article

  • Praat scripting

    - by Binaryrespawn
    Hi all, I am trying to write a praat script to do preprocessing on hundreds of speach samples. I need to extract speech features from each sample and feed these as imputs into a feed-forward neural network. I have already constructed the network using math-lab. However, learing to script in praat is proving to be quite a challenge given my time constraints. Some of my samples are 0.01 to 0.03 seconds in length, I was looking at standardising the duration for all samples using Pitch Synchronous OverLap-Add(PSOLA). However this will be very tedious if I were to do this for every sample. Is there any script that can read in all of my files and perform the operations in a batch mode? Any guidance will be surelly appreaciated. Regards.

    Read the article

  • Substring extraction using bash shell scripting and awk

    - by rohanbk
    So, I have a file called 'dummy' which contains the string: "There is 100% packet loss at node 1". I also have a small script that I want to use to grab the percentage from this file. The script is below. result=`grep 'packet loss' dummy` | awk '{ first=match($0,"[0-9]+%") last=match($0," packet loss") s=substr($0,first,last-first) print s}' echo $result I want the value of $result to basically be 100% in this case. But for some reason, it just prints out a blank string. Can anyone help me?

    Read the article

  • shell scripting: nested subshell ++

    - by jhon
    Hi guys, more than a problem, this is a request for "another way to do this" actually, if a want to use the result from a previous command I into another one, I use: R1=$("cat somefile | awk '{ print $1 }'" ) myScript -c $R1 -h123 then, a "better way"is: myScript -c $("cat somefile | awk '{ print $1 }'" ) -h123 but, what if I have to use several times the result, let's say: using several times $R1, well the 2 options: option 1 R1=$("cat somefile | awk '{ print $1}'") myScript -c $R1 -h123 -x$R1 option 2 myScript -c $("cat somefile | awk '{ print $1 }'" ) -h123 -x $("cat somefile | awk '{ print $1 }'" ) do you know another way to "store" the result of a previous command/script and use it as a argument into another command/script? thanks

    Read the article

  • Shell Scripting For loop Syntax Error

    - by NewShellScripter
    Hello, I am trying to make a simple shell script to ping a source but I am getting bash-2.03$ ./test.sh google.com 10 .5 /home/users/me 16 256 ./test.sh: line 35: syntax error near unexpected token `((' ./test.sh: line 35: `for (( i = 1 ; i <= $totalArguments ; i++ ))' This is the code: #!/bin/bash ip=$1 count=$2 interval=$3 outputDirectory=$4 shift; shift; shift; shift; totalArguments=$# for (( i = 1 ; i <= $totalArguments ; i++ )) do ping -c $count -i $interval -s ${!i} $ip >> $outputDirectory/${!i}results.txt done Can someone tell me what I am doing wrong with the for loop syntax? Thanks!

    Read the article

  • UNIX Programs (Shell Scripting) [closed]

    - by atif089
    Hi, I have an exam tomorrow and I need some help with these programs. Or if you can tell me where I can get these. Write a program which uses grep to search a file for a pattern and display search patterns on standard output Write an awk program to print only odd numbered lines of a file. Write a program to open the command ls and give the output to the command through which we count the number of files Thank You :)

    Read the article

  • patterns in case statement in bash scripting

    - by Ramiro Rela
    The man says that case statements use "filename expansion pattern matching". I usually want to have short names for some parameters, so I go: case $1 in req|reqs|requirements) TASK="Functional Requirements";; met|meet|meetings) TASK="Meetings with the client";; esac logTimeSpentIn "$TASK" I tried patterns like "req*" or "me{e,}t" which I understand would expand correctly to match those values in the context of filename expansion, but it doesn't work. Thanks.

    Read the article

  • Shell scripting and test expressions

    - by Paul
    Hi, I'm trying to test whether a directory path exists when a file is passed to my script. I use dirname to strip and save the path. I want my script to run only if the path exists. This is my attempt below. FILE=$1 DIRNAME=dirname $FILE if [ -z $DIRNAME ] ; then echo "Error no file path" exit 1 fi But this doesn't work. Actual when there is no file path dirname $FILE still returns "." to DIRNAME, i.e. this directory. So how do i distinguish between "." and "/bla/bla/bla". Thanks.

    Read the article

  • shell scripting error logging

    - by Eddy
    Hi all, I'm trying to setup a simple logging framework in my shell scripts. For this I'd like to define a "log" function callable as log "LEVEL" $message Where the message is a variable to which I have previously redirected the outputs of executed commands. My trouble is that I get errors with the following {message=command 2&3 1&3 3&-} &3 log "INFO" $message There's something wrong isn't there? TIA

    Read the article

  • Shell Scripting: Generating output file name in script and then writing to it

    - by NewShellScripter
    Hello, I have a shell script where a user passes different sizes as command line arguments. For each of those sizes, I want to perform some task, then save the output of that task into a .txt file with the size in the name. How can I take the command line passed and make that part of a stringname for the output file? I save the output file in a directory specified by another command line argument. Perhaps an example will clear it up. In the foor lop, the i value represents the command line argument I need to use, but $$i doesnt work. ./runMe arg1 arg2 outputDir [size1 size2 size3...] for ((i=4; i<$#; i++ )) do ping -s $$i google.com >> $outputDir/$$iresults.txt done I need to know how to build the $outputDir/$$iresults.txt string. Also, the ping -s $$i doesnt work. Its like I need two levels of replacement. I need to replace the $[$i] inner $i with the value in the loop, like 4 for ex, making it $4. Then replace $4 with the 4th command line argument! Any help would be greatly appreciated. Thanks!

    Read the article

  • How to close all tabs in Safari using AppleScript?

    - by Form
    I have made a very simple AppleScript to close all tabs in Safari. The problem is, it works, but not completely. Here's the code: tell application "Safari" repeat with aWindow in windows repeat with aTab in tabs of aWindow aTab close end repeat end repeat end tell I've also tried this script: tell application "Safari" repeat with i from 0 to the number of items in windows set aWindow to item i of windows repeat with j from 0 to the number of tabs in aWindow set aTab to item j of tabs of aWindow aTab close end repeat end repeat end tell ... but it does not work either. I tried that on my system (MacBook Pro jan 2008), as well as on a Mac Pro G5 under Tiger and the script fails on both, albeit with a much less descriptive error on Tiger. The problem is that only a couple of tabs are closed. Running the script a few times closes a few tab each time until none is left, but always fails with the same error after closing a few tabs. Under Leopard I get an out of bounds error. Since I am using fast enumeration (not using "repeat from 0 to number of items in windows") I don't see how I can get an out of bounds error with this... My goal is to use the Cocoa Scripting Bridge to close tabs in Safari from my Objective-C Cocoa application but the Scripting Bridge fails in the same manner. The non-deletable tabs show as NULL in the Xcode debugger, while the other tabs are valid objects from which I can get values back (such as their title). In fact I tried with the Scripting Bridge first then told myself why not try this directly in AppleScript and I was surprised to see the same results. I must have a glaring omission or something in there... (seems like a bug in Safari AppleScript support to me... :S) I've used repeat loops and Obj-C 2.0 fast enumeration to iterate through collections before with zero problems, so I really don't see what's wrong here. Anyone can help? Thanks in advance!

    Read the article

< Previous Page | 8 9 10 11 12 13 14 15 16 17 18 19  | Next Page >