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• How do I bind a key to "the function represented by the following key sequence"?

  - by katrielalex

  I'm just starting to learn emacs (woohoo!) and I've been mucking around in my .emacs quite happily. Unfortunately, I don't know Lisp yet, so I'm having issues with the basics. I've already remapped a few keys until I fix my muscle memory: (global-set-key (kbd "<f9>") 'recompile) That's fine. But how can I tell a key to 'simulate pressing several keys'? For instance, I don't know, make <f1> do the same as C-u 2 C-x } (widen buffer by two chars). One way is to look up that C-x } calls shrink-window-horizontally, and do some sort of lambda thing. This is of course the neat and elegant way (how do you do this?). But surely there's a way to define <f1> to send the keystrokes C-u 2 C-x }?

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• Mapping over multiple Seq in Scala

  - by bsdfish

  Suppose I have val foo : Seq[Double] = ... val bar : Seq[Double] = ... and I wish to produce a seq where the baz(i) = foo(i) + bar(i). One way I can think of to do this is val baz : Seq[Double] = (foo.toList zip bar.toList) map ((f: Double, b : Double) => f+b) However, this feels both ugly and inefficient -- I have to convert both seqs to lists (which explodes with lazy lists), create this temporary list of tuples, only to map over it and let it be GCed. Maybe streams solve the lazy problem, but in any case, this feels like unnecessarily ugly. In lisp, the map function would map over multiple sequences. I would write (mapcar (lambda (f b) (+ f b)) foo bar) And no temporary lists would get created anywhere. Is there a map-over-multiple-lists function in Scala, or is zip combined with destructuring really the 'right' way to do this?

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• Removing whitespace in Java string?

  - by waitinforatrain

  Hi guys, I'm writing a parser for some LISP files. I'm trying to get rid of leading whitespace in a string. The string contents are along the lines of: :FUNCTION (LAMBDA (DELTA PLASMA-IN-0) (IF (OR (>= #61=(+ (* 1 DELTA) PLASMA-IN-0) 100) (<= #61# 0)) PLASMA-IN-0 #61#)) The tabs are all printed as 4 spaces in the file, so I want to get rid of these leading tabs. I tried to do this: string.replaceAll("\\s{4}", " ") - but it had no effect at all on the string. Does anyone know what I'm doing wrong? Is it because it is a multi-line string? Thanks

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• Storing expression template functors

  - by UncaughtException

  Hello guys, at the moment I'm really interested in expression templates and want to code a library for writing and differentiating mathematical functions with a lambda-style syntax. At the moment, I'm able to write (_x * _x)(2); and get the correct result 4. But I would really like to do something like MathFunction f = _x * _x; f(2);, but I don't have any ideas on how to cope with the recursive expression templates on the right side. Is it possible to achieve this without using the 'auto'-Keyword instead of MathFunction or having to make the operator() virtual? Thanks for your help!

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• Vb.Net action delegate problem?

  - by Ramesh Vel

  Hi, Am vb.net newbie. This question might be very novice and answered before, but i couldn't find. I was trying the lambda features and got struck here. Private Function HigerOrderTest(highFunction as Func(Of Int16,Int16)) As Action(of String) Dim sam = highFunction(3) Dim DoIt as Action(of String) DoIt = sub(s) console.WriteLine(s) return DoIt End Function I got "Expression expected." at line DoIt = sub(s) console.WriteLine(s). And when i changed this to DoIt = function(s) console.WriteLine(s) i got Expression does not produce a value. error. Whats the problem? Cheers

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• What is the best way to set default values in ActiveRecord?

  - by ryw

  What is the best way to set default value in ActiveRecord? I see a post from Pratik that describes an ugly, complicated chunk of code: http://m.onkey.org/2007/7/24/how-to-set-default-values-in-your-model class Item < ActiveRecord::Base def initialize_with_defaults(attrs = nil, &block) initialize_without_defaults(attrs) do setter = lambda { |key, value| self.send("#{key.to_s}=", value) unless !attrs.nil? && attrs.keys.map(&:to_s).include?(key.to_s) } setter.call('scheduler_type', 'hotseat') yield self if block_given? end end alias_method_chain :initialize, :defaults end YUCK! I have seen the following examples googling around: def initialize super self.status = ACTIVE unless self.status end and def after_initialize return unless new_record? self.status = ACTIVE end I've also seen people put it in their migration, but I'd rather see it defined in the model code. What's the best way to set default value for fields in ActiveRecord model?

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• Linq To SQL: Retain list order when using .Contains

  - by rockinthesixstring

  I'm using Lucene.net to build a MyListOfIds As List(Of Integer) which I then pass on to my Linq service. I then search the database as follows Return _EventRepository.Read().Where(Function(e) MyListOfIds.Contains(e.ID)).ToList Now I know that Lucene is already ordering MyListOfIds based on the weight it gave each term. What sucks is that Linq is losing that order in it's SQL search. My Question: How can I retain that sort order when building my Lambda expression? I tried using LINQPad to see how the query is being built, but because I had to declare a variable LINQPad didn't show me the resultant SQL :-( Here's what I tried in LINQPad Dim i As New List(Of Integer) i.Add(1) i.Add(100) i.Add(15) i.Add(3) i.Add(123) Dim r = (From e In Events Where i.Contains(e.ID) Select e) note: my example is in VB.NET, but I don't mind if responses are in C#

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• deploying a war to tomcat using python

  - by Decado

  Hi, I'm trying to deploy a war to a Apache Tomcat server (Build 6.0.24) using python (2.4.2) as part of a build process. I'm using the following code import urllib2 import base64 war_file_contents = open('war_file.war','rb').read() username='some_user' password='some_pwd' base64string = base64.encodestring('%s:%s' % (username, password))[:-1] authheader = "Basic %s" % base64string opener = urllib2.build_opener(urllib2.HTTPHandler) request = urllib2.Request('http://158.155.40.110:8080/manager/deploy?path=war_file', data=war_file_contents) request.add_header('Content-Type', 'application/octet-stream') request.add_header("Authorization", authheader) request.get_method = lambda: 'PUT' url = opener.open(request) the url.code is 200, and the url.msg is "OK". However the web archive doesn't appear on the manager list applications page. Thanks.

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• Safely dereferencing FirstOrDefault call in Linq c#

  - by samy

  For brevity's sake in my code, i'd like to be able to do the following: having a collection, find the first element matching a lambda expression; if it exists, return the value of a property or function. If it doesn't exist, return null. var stuff = {"I", "am", "many", "strings", "obviously"}; var UpperValueOfAString = stuff.FirstOrDefault(s => s.contains("bvi")).ToUpper(); // would return "OBVIOUSLY" var UpperValueOfAStringWannabe = stuff.FirstOrDefault(s => s.contains("unknown token")).ToUpper(); // would return null Is it possible with some linq-syntax-fu or do i have to check explicitly for the return value before proceeding?

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• Haskell: Problems with overloading: Interpreter can´t tell which + to use

  - by Ben

  Hi, I want to make functions Double - Double an instance of the Num typeclass. I want to define the sum of two functions as sum of their images. So I wrote instance Num Function where f + g = (\ x - (f x) + (g x)) Here the compiler complains he can´t tell whether I´m using Prelude.+ or Module.+ in the lambda expression. So I imported Prelude qualified as P and wrote instance Num Function where f + g = (\ x - (f x) P.+ (g x)) This compiles just fine, but when I try to add two functions in GHCi the interpreter complains again he can´t tell whether I´m using Prelude.+ or Module.+. Is there any way I can solve this problem?

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• Using Where method in Linq 2 Entities with OR clause.

  - by Dani

  I want to use Where method in Linq 2 entities that will be equal to this userRepository.Users.Where(u=>u.RoleID == 1 || u=>u.RoldID == 2).Select(o => new SelectListItem { Text = o.Role.RoleName, Value = o.RoleID.ToString() }).ToList(); The problem of course is in Where(u=u.RoleID == 1 || u=u.RoldID == 2) The problem is that I don't know how to use WHERE method with OR inside the WHERE clause. any ideas (the code above will not compile of-course b/c of the lambda expression. userRepository.Users returns an list of Users entities. I guess that and can be done using concatenation of .Where().Where() but I need an OR.

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• Python sort 2-D list by time string

  - by Mark Kennedy

  How do I sort a multi dimensional list like this based on a time string? The sublists can be of different sizes (i.e. 4 and 5, here) I want to sort by comparing the first time string in each sublist (sublist[-4]) x = (['1513', '08:19PM', '10:21PM', 1, 4], ['1290', '09:45PM', '11:43PM', 1, 4], ['0690', '07:25AM', '09:19AM', 1, 4], ['0201', '08:50AM', '10:50AM', 1, 4], ['1166', '04:35PM', '06:36PM', 1, 4], ['0845', '05:40PM', '07:44PM', 1, 4], ['1267', '07:05PM', '09:07PM', 1, 4], ['1513', '08:19PM', '10:21PM', 1, 4], ['1290', '09:45PM', '11:43PM', 1, 4], ['8772', '0159', '12:33PM', '02:43PM', 1, 5], ['0888', '0570', '09:42PM', '12:20AM', 1, 5], ['2086', '2231', '04:10PM', '06:20PM', 1, 5]) The sorted result would be sortedX = (['0690', '07:25AM', '09:19AM', 1, 4], ['0201', '08:50AM', '10:50AM', 1, 4], ['1166', '04:35PM', '06:36PM', 1, 4], ['0845', '05:40PM', '07:44PM', 1, 4], ['1267', '07:05PM', '09:07PM', 1, 4], ['1513', '08:19PM', '10:21PM', 1, 4], ['1513', '08:19PM', '10:21PM', 1, 4], ['1290', '09:45PM', '11:43PM', 1, 4], ['1290', '09:45PM', '11:43PM', 1, 4], ['8772', '0159', '12:33PM', '02:43PM', 1, 5], ['2086', '2231', '04:10PM', '06:20PM', 1, 5], ['0888', '0570', '09:42PM', '12:20AM', 1, 5]) I tried the following: sortedX = sorted(x, key=lambda k : k[-4]) #k[-4] is the first time string and it works but it doesn't respect the sublist size ordering

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• mysterious difference between rake test and ruby

  - by standup75

  Here is the mysterious: I have a scope which looks like this (in Image.rb) scope :moderate_all, delegates.where("moderation_flag = #{$moderation_flags[:not_moderated]}") Note that delegates is another scope that I am defining before moderate_all When I leave it like this, I can run my test that checks if an image has been "checked-out" it is not available anymore. I don't put the code of the test, because it does not matter actually. With this code, when I run "rake test" it fails, but if I do "ruby test/unit/image_test.rb" it works! I was thinking I am starting to have a bad day. Then I tried scope :moderate_all, lambda { delegates.where("moderation_flag = #{$moderation_flags[:not_moderated]}") } And "rake test" passes! So my problem is solved, but why?

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• mootools: $ not defined

  - by eaigner

  I've strange error i don't understand. I'm just moving my code from jQuery over to Mootools because it's much cleaner than the jQuery mess. Now when i use the $$('div.canvas') in mootools i get the correct element. When i try $(document).getElement('div.canvas') it tells me that $ is not defined. How can $$ and all helper functions like $lambda etc. be defined but not $? Has something changed there from 1.1 to 1.2 and the docs are not updated yet?

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• Adding items to dictionary if condition is true, else dont - python

  - by CodeTalk

  I'm trying to take an existing process: if self.path_object is not None: dictpath = {} for path in self.path_object: self.params = path.pathval.split("?")[0] self.params = path.pathval.split("&", 2) if path.pathval.contains(self.params): out = list(map(lambda v: v.split("=")[0] +"=" + str(self.fuzz_vectors), self.params)) else: pass dictpath[path] = out print dictpath I added the sub-if/else block in, but it is failing, stating: AttributeError: 'unicode' object has no attribute 'contains' on the if block . How can I fix it? I'm simply trying to do: if the path.pathval has either ? or & in it: add to dictionary else: pass #forget about it. Thanks!

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• How do I delete an object from an Entity Framework model without first loading it?

  - by Tomas Lycken

  I am quite sure I've seen the answer to this question somewhere, but as I couldn't find it with a couple of searches on SO or google, I ask it again anyway... In Entity Framework, the only way to delete a data object seems to be MyEntityModel ent = new MyEntityModel(); ent.DeleteObject(theObjectToDelete); ent.SaveChanges(); However, this approach requires the object to be loaded to, in this case, the Controller first, just to delete it. Is there a way to delete a business object referencing only for instance its ID? If there is a smarter way using Linq or Lambda expressions, that is fine too. The main objective, though, is to avoid loading data just to delete it.

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• How to compare two lists with duplicated items in one list?

  - by eladc

  I need to compare list_a against many others. my problem starts when there's a duplicated item in the other lists (two k's in other_b). my goal is to filter out all the lists with the same items (up to three matching items). list_a = ['j','k','a','7'] other_b = ['k', 'j', 'k', 'q'] other_c = ['k','k','9','k'] >>>filter(lambda x: not x in list_a,other_b) ['q'] I need a way that would return ['k', 'q'], because 'k' appears only once in list_a. comparing list_a and other_c with set() isn't good for my purpose since it will return only one element: k. while I need ['k','9','k'] I hope I was clear enough. Thank you

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• pass parameter from controller to models condition

  - by Alex

  I'm trying to bind a param to a join via a named scope., but I'm getting an error. What is the correct way to do that? has_one :has_voted, :class_name => 'Vote', :conditions => ['ip = :userIp'] # named scopes scope :with_vote, lambda {|ip| { :include => [:has_voted], # like this ?? :conditions => [:has_voted => {:conditions => {:userIp => ip}} ] }} Idea.with_vote(request.ip).all I believe I need the condition definition in the model for it to appear in the ON clause of a JOIN, rather then in the WHERE one. Edit I'm trying to get the following query select Ideas.*, Votes.* from Ideas left outer join Votes on Votes.Idea_id = Idea.id AND Votes.ip = {request.ip}

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• Text in gtk.ComboBox without active item

  - by Yotam

  The following PyGTk code, gives a combo-box without an active item. This serves a case where we do not want to have a default, and force the user to select. Still, is there a way to have the empty combo-bar show something like: "Select an item..." without adding a dummy item? import gtk import sys say = sys.stdout.write def cb_changed(w): say("Active index=%d\n" % w.get_active()) topwin = gtk.Window() topwin.set_title("No Default") topwin.set_size_request(0x100, 0x20) topwin.connect('delete-event', gtk.main_quit) vbox = gtk.VBox() ls = gtk.ListStore(str, str) combo = gtk.ComboBox(ls) cell = gtk.CellRendererText() combo.pack_start(cell) combo.add_attribute(cell, 'text', 0) combo.connect('changed', cb_changed) ls.clear() map(lambda i: ls.append(["Item-%d" % i, "Id%d" % i]), range(3)) vbox.pack_start(combo, padding=2) topwin.add(vbox) topwin.show_all() gtk.main() say("%s Exiting\n" % sys.argv[0]) sys.exit(0)

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• Syntax errors on Heroku, but not on local server

  - by Phil_Ken_Sebben

  I'm trying to deploy my first app on Heroku (rails 3). It works fine on my local server, but when I pushed it to Heroku and ran it, it crashes, giving a number of syntax errors. These are related to a collection of scopes I use like the one below: scope :scored, lambda { |score = nil| score.nil? ? {} : where('products.votes_count >= ?', score) } it produces errors of this form: "syntax error, unexpected '=', expecting '|' " "syntax error, unexpected '}', expecting kEND" Why is this syntax making Heroku choke and how can I correct it? Thanks!

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• Image equivalent of ActionLink in ASP.NET MVC

  - by Jason Whitehorn

  In ASP.NET MVC is there an equivalent of the Html.ActionLink helper for Img tags? I have a controller action that outputs a dynamically generated JPEG and I wanted to use the same Lambda expressions to link to it as I do HREFs using ActionLink. Alternatively, a helper that just gives the URL to a route (again specified using Lambdas) would also be acceptable. EDIT: I had originally specified that I was using Preview 5, however I see that a Beta has been released. So all-in-all the version number was an unneeded piece of info as I may be upgrading soon :-)

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• How to rewrite the following?(C#3.0)

  - by Newbie

  I am trying to write the following double sum_res = 0.0; double yhat = 0; double res = 0; int n = 0; for(int i=0;i<x.Count;i++) { yhat = inter + (slp*x[i]); res = yhat - y[i]; n++; } using lambda but somehow not able to get it work(compile time error) Enumerable.Range(0, x.Count).Select(i => { yhat = inter + (slp * x[i]); res = yhat - y[i]; sum_res += res * res; n++; }); Error: The type arguments for method 'System.Linq.Enumerable.Select(System.Collections.Generic.IEnumerable, System.Func)' cannot be inferred from the usage. Try specifying the type arguments explicitly. Help needed. Thanks

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• Create an Action<T> to "set" a property, when I am provided with the LINQ Expression for the "get"

  - by Alex

  I'd like to be able to generate a compiled expression to set a property, given the lambda expression that provides the "get" method for a property. Here's what I'm looking for: public Action<int> CreateSetter<T>(Expression<Func<T, int>> getter) { // returns a compiled action using the details of the getter expression tree, or null // if the write property is not defined. } I'm still trying to understand the various types of Expression classes, so if you can point me in the right direction that would be great.

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• How to understand the functional programming code for converting IP string to a number?

  - by zfz

  In a python discusion, I saw a way to convert IP string to a integer in functional progamming way. Here is the Link . The function is implemented in a single line. def ipnumber(ip): return reduce(lambda sum, chunk: sum <<8 | chunk, map(int, ip.split("."))) However, I have few ideas of funcional programming. Could anybody explain the function in detail? I've some knowledg of "map" and "reduce". But I don't konw what "|" and "chunk" mean here? Thanks.

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• python equivalent of filter() getting two output lists

  - by FX

  Let's say I have a list, and a filtering function. Using something like >>> filter(lambda x: x > 10, [1,4,12,7,42]) [12, 42] I can get the elements matching the criterion. Is there a function I could use that would output two lists, one of elements matching, one of the remaining elements? I could call the filter() function twice, but that's kinda ugly :) Edit: the order of elements should be conserved, and I may have identical elements multiple times.

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