Tagged Questions
-2
votes
0answers
21 views
Python lambda vs Functional programming's lambda [on hold]
Could someone explain the basic difference between Python's lambda and functional programming's lambda?
0
votes
0answers
5 views
fixed point and head normal form
I have this question, given the lambda term s = [ Lambda xy.y(xy) ] , fixed points can be found by applying fixed point combinators such as y and theta, then get for example t = ys or t = theta(s), ...
0
votes
1answer
23 views
Is the following a legit successor function for lambda calculus ? (Church Numeral)
I have read from the books that, the successor for Church Numerals is of the form:
(\lambda n f x. f (n f x) )
Last night I came up with this:
(\lambda a b c. (a b) (b c) )
I believe it also ...
-2
votes
1answer
61 views
How to make Lambda real
So I use a command to save variables into a serialized file. I save the following data:
data.Save("ships", this.ships.Select(x => x.Name));
This is supposed to output an IEnumerable but instead ...
1
vote
1answer
83 views
Comparing Two lists of Different Objects without for loop
I have two lists:
List<ObjA> AList;
List<ObjB> BList;
Now I have a method to compare individual Obj A to Obj B:
void CompareObjAToObjB(ObjA a, ObjB b)
{
....
}
where it asserts ...
2
votes
3answers
43 views
Concatenating strings in two lists to create a third list
I have two lists of items, can you please guide me how I can concatenate values of both and add concatenated value into third list as a value.
For example if List<string> From has A,B,C and ...
2
votes
2answers
50 views
Explaination of this lambda function please?
I sorted a list of tuples using sorted(list_of_tuples, key = lambda tup: tup[1]) from code I found on the internet. I don't understand how the lambda function works in this command. Is the lambda ...
0
votes
1answer
36 views
query a dictionary by a data member of a class in C# by LINQ
I am working on C# Win 7.
I need to get a query from a dictionary.
Dictionary<string, myClass> myDict;
public class myClass
{
public int myId;
public Dictionary<string, ...
0
votes
1answer
24 views
Prevent code replication with lambda functions when using out parameters
I have to parse the content of many TextBox that contain various numeric data types (int, double, ...).
To be valid, the text does not only have to be parsable as int, or dobule or whatever, it also ...
1
vote
0answers
78 views
How to write group by query in dynamic linq query
I am struggling to write 'Group by query' in dynamic linq query.
public IEnumerable<DashboardReport> GetDashTransactionsReports(string dimensionColumn)
{
var result = (from t in ...
0
votes
2answers
154 views
Haskell Applying 2 lambda expressions to list of tuples
I'm struggling to understand lambda expressions in Haskell.
He is the problem:
I have a list of tuples [(a,b),(c,d),(e,f)...] (it can be of any length)
I want to apply two functions f1 and f2 to ...
-1
votes
1answer
40 views
I don't understand lambda in Scheme. Can someone please explain Thanks
Can someone please explain how lambda works in scheme? For example how it works here:
(define (prepend-every prefix sent)
(every (lambda (wd) (word prefix wd)) sent))
Or here:
(define ...
0
votes
2answers
63 views
filling an object from list using Lambda?
I m new to Lambda and from a list of object want to filter a list and an individual object.
Two types are as below:
Users
Id,Name,Password, EmailAddress
Credentials
Id,Password
Can you ...
0
votes
1answer
75 views
OrderBy with Linq.Expression
I have a problem to create a sort expression.
I have an expression of type Expression<Func<Products, bool>> that already contains a query expression.
I am wanting to do the query ...
1
vote
0answers
67 views
Indent code when using lamba expressions in vb.net
By default, intellisense in visual studio reorganize and indent your code when you
create a lamba sub() in vb.net. Something like the code example below (example 1).
I always try to organice it but I ...
1
vote
2answers
451 views
Haskell - Lambda calculus equivalent syntax?
While writing some lambda functions in Haskell, I was originally writing the functions like:
tru = \t f -> t
fls = \t f -> f
However, I soon noticed from the examples online that such ...
0
votes
2answers
127 views
Ruby and Lambda calculus
I'm trying to understand lambda calculus with procs and ruby. Here is some code:
puts -> x { -> y {x.call(y) } }
# => #<Proc:0x2a3beb0@C:/first-ruby.rb:1 (lambda)>
puts -> x { x + ...
1
vote
2answers
76 views
error when storing a reference to a method in C++11
I want to work with lambda functions but I have a problem:
If I want to store a reference to a function declared in the "global scope" as std::function, there is no problem:
int myFunction()
{
...
3
votes
3answers
122 views
lambda functions and memory in scheme
I don't understand why if I write
(define (iter-list lst)
(let ((cur lst))
(lambda ()
(if (null? cur)
'<<end>>
(let ((v (car cur)))
(set! cur ...
0
votes
1answer
37 views
List<dynamic>.Find and List<dynamic>.FindAll
I am trying to do this but unable to find a workaround.
I have a list of dynamic objects and its like ObjectList : List<dynamic>
its filled with objects that have a dynamic property LastName.
...
1
vote
2answers
256 views
Duplicate values using linq
I have the Input format in following way
S.no Name wages
1 Tom $200
1 Tom $300
1 Tom $400
2 Rob $500
2 Rob $600
Result set should be in ...
0
votes
1answer
101 views
Anonymous Method in Object initializer
I am creating a quiz in which have following class
Quiz with properties CorrectOption, WrongOption1, WrongOption2, WrongOption3.
in its DTO i have the List<String> Options that will contain ...
2
votes
1answer
397 views
C# passing a list of strongly typed property names
I'm looking for a way to pass in a list of strongly typed property names into a method that I can then dissect and get the properties that the caller is interested in. The reason I want to do this is ...
0
votes
0answers
46 views
How to update the record in linq
I will be having the records for the rows.
The records will be like
rowid rowname
1 first
1 second
2 third
3 fourth
3 fifth
4 sixth
5 ...
1
vote
1answer
606 views
How to compare array of elements with the linq query result in c#
How can i compare array of elements with the linq query. I will pass array of elements to the controller and i want to compare and display the records that only contains the passed elements.
I will ...
3
votes
1answer
1k views
Lambda Expression for “not in”?
well i have a collection as it
detailcollection which every detail have
code,price,name
now i have a string with some codes
string codes="1,2,3"
i know i can get a array using split
string[] ...
3
votes
5answers
271 views
How can I create dynamic Lambda Expressions
I have a question, how do I add another filter and this I have to validate that was selected?
private Expression < Func < Entity.Modelos.Flux, bool >> Filter() {
var dateStart = ...
0
votes
5answers
133 views
using lambda to verify all elements in list
i have a list of foods called "my_foods".
i would like to use a lambda function to verify that all elements from the list "good_foods" appear in the list "my_foods", and also verify that none of the ...
1
vote
1answer
243 views
Find a normal form using beta reduction
Given the following expression :
((λx.λx.xx) (λx.xzx)) (λy.yy)
I want to find its normal form using beta reduction.
My calculation :
((λx.λx.xx) (λx.xzx)) (λy.yy) ->
((λx.xzx)(λx.xzx)) ...
0
votes
1answer
133 views
Passing parameters to a slot function using lambda
#!/usr/bin/python
# -*- coding: utf-8 -*-
import sys
from PyQt4 import QtGui, QtCore
class Example(QtGui.QMainWindow):
def __init__(self):
super(Example, self).__init__();
...
-3
votes
1answer
46 views
How to get arguments names in a list and create in lambda python?
argsneeded = ["dividend","divisor"]
lambda ?????: a/b
What should I put in the ????s?
I'm creating a record and replay tool 4 python, argsneeded is an arbitrary list gained by sys.traceit to get ...
28
votes
1answer
3k views
Can lambda functions be recursive? [duplicate]
Possible Duplicate:
Recursive lambda functions in c++0x
Here is a plain old recursive function:
int fak(int n)
{
return (n <= 1) ? 1 : n * fak(n - 1);
}
How would I write such a ...
12
votes
2answers
471 views
JDK8 lambdas to begin with conceived as no true closures? [closed]
I had a look at JDK8 lambdas recently and discovered that the old problem with variables handed over from the outer context into an anonymous class still exists with JDK8 lambdas (the var then has to ...
1
vote
2answers
296 views
Hierarchical Structures Database Select By Lambda Expression
Hierarchical Structures Database Select By Lambda Expression
Hi My Table Structure is recursive
ID
ParentID
UserGROUPNAME
How Can I select Subset an Id from my contex By Lambda Expression ...
0
votes
5answers
1k views
Split a list into multiple lists using lambda expression
class order {
Guid employeeId;
DateTime time;
}
I need to filter a list of orders into 4 lists based on the time range. 0-9AM to 1st list, 9AM-2PM to 2nd, 2-6PM to 3rd and 6-12PM to a 4th ...
0
votes
1answer
1k views
Lambda OrderBy method
I have a graphing class to detect circular dependencies in some business logic I am writing. My graphing class builds nodes that knows the relationship to other nodes.
I have nodeList as List(of ...
5
votes
5answers
2k views
Get Value and Count of that value using LINQ or lambda expression
A list of data object in the below format
Col1 Col2 Col3
B 45 36
B 12 69
A 46 76
C 89 09
B 451 37
D 435 46
A 450 50
D 98 ...
0
votes
2answers
143 views
Dynamic lambda expression [closed]
I have created an expression like:
expression = x => x.CustomerName.StartsWith(comboParams.ParamValueText, true, null);
I would like access customer name as generic something like this:
...
0
votes
1answer
745 views
LINQ Queries with dynamic OrderBy on property and complex object
With the code below, I don't have any problem to sort on FirstName and LastName
but I'd like be able to sort on Name and Code too. Is there a solution to sort on a property and this property is a ...
0
votes
5answers
104 views
C# Possible lambda in array's content declaration
I have such piece of code:
string suffix = "wallpapers\\";
string extenstion = ".jpg";
string[] wallpapers;
.....
void SetWallPapers()
{
wallpapers = new string[] {
...
1
vote
2answers
145 views
Lambda implementation for OR expression concatenation
I am new to lambda expressions; I am learning by implementing them. I have a question on how to convert a for-loop into a lambda expression.
EnumHelper.GetEnumFromString is a helper method that ...
1
vote
1answer
401 views
Lambdaj: Loop through Map and get the values and put in other Map
I'm new to lambdaj so trying to get more used to it. I want to update this code using lambdaj:
Passed in parameter Map<String, Device> devices;
final Map<String, String> resultHash = ...
0
votes
2answers
640 views
Why std::generate will work with lambda generator and std::fill will not?
I have stumbled across this website : http://www2.research.att.com/~bs/C++0xFAQ.html#lambda where they explain lambda functions. I have tried to use the provided examples, namely :
...
2
votes
5answers
1k views
Lambda Max and Max and Max
Quick and probably easy Lambda question:
I have a restaurant with reviews.
I want to query for the one with the:
Max(AverageRating)
And the Max(ReviewCount)
And the Max(NewestReviewDate)
And the ...
1
vote
2answers
236 views
Why are lambda expressions called lambda expressions? [closed]
I may be showing my ignorance here, but why are lambda expressions called lambda expressions. I understand how to use them, but I'm curious if there is any significance to the term "lambda".
3
votes
1answer
575 views
Using lambdas as asynchronous callbacks
I have a program, where I cannot use the standard std::async and threading mechanisms. Instead I have to code the program like so:
void processor( int argument, std::function<void(int)> ...
6
votes
1answer
238 views
Syntax tree for lambda calculus
I'm trying to figure out how I would draw a syntax tree for the expression below. First, how exactly is this behaving? It looks like it takes 1 and 2 as parameters, and if n is 0, it will just return ...
11
votes
1answer
255 views
How can I use lambda function within itself?
I have this code and don't know if what I would like to achieve is possible.
_acceptor.async_accept(
_connections.back()->socket(),
[this](const boost::system::error_code& ec)
{
...
8
votes
5answers
2k views
In lambda functions syntax, what purpose does a 'capture list' serve?
Taken from an answer to this question, as an example, this is a code that calculates the sum of elements in a std::vector:
std::for_each(
vector.begin(),
vector.end(),
[&](int n) {
...
0
votes
4answers
539 views
Python: to wrap functions via lambda
I have some code like
class EventHandler:
def handle(self, event):
pass
def wrap_handler(handler):
def log_event(proc, e):
print e
proc(e)
handler.handle = lambda ...
