I had an idea for a higher-order function today that I'm not sure how to write. I have several sparse, lazy infinite sequences, and I want to create an abstraction that lets me check to see if a given number is in any of these lazy sequences. To improve performance, I wanted to push the values of the sparse sequence into a hashmap (or se...
Hey, I have an Array of MKAnnotation objects called arrAnnotations. I want to pick out one of the annotations with the same coordinate as the one stored in a CLLocation object called "newLocation". I'm trying to use an NSPredicate, but it doesn't work. NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(SELF.coordinate == %f)...
I have a function A that accepts a predicate function as its argument. I have another function B and it takes a char and returns an int, and a function C that accepts int and returns a bool. My question is how to bind B and C to pass it to function A. Something like: A(bindfunc(B,C)) I know boost::bind works but i am looking for ...
I need just to clarify that given collection contains an element. I can do that via collection.Count(foo => foo.Bar == "Bar") > 0) but it will do the unnecessary job - iterate the whole collection while I need to stop on the first occurrence. But I want to try to use Contains() with a predicate, e.g. foo => foo.Bar == "Bar". Currentl...
I'm building a series of predicates that duplicate lots of code, and so are being changed into a single template function class based on the std::unary_function. The idea is that my class interface requires methods such as Element_t Element() and std::string Name() to be defined, so the predicate template arguments are the object type an...
Suppose I have two tables, TableA and TableB. Each record in A has one or more related records in B. Say I want a reusable filter using predicates. I might do something like this (Linq-to-SQL by the way): private Expression<Func<ARecord, bool>> FilterPredicate() { return x => x.Name == "Test"; } private IQueryable<ARecord> GetRecor...
Hello, I have a problem with Core Data which has left me at the end of my tether. So I was wondering if any of you wonderful people could help. Basically, I have two entities in a Core Data project. These are: Author {authorName, dateOfBirth} Book {bookName, pages} There is a one-to-many relationship from author to books called 'auth...
This is a general question, but here is the specific case I'm looking for a solution to: I have a Dictionary<int, List<string>> I want to apply various predicates to. I want one method that can take care of multiple LINQ queries such as these: from x in Dictionary where x.Value.Contains("Test") select x.Key from x in Dictionary where ...
i understand that predicates are delegate to function which return bool and take generic param , i understand that when i say mycustomer => mycustomer.fullname == 1 it actually means: delegate (Customer mycustomer) { return mycustomer.fullName == "John"; } the paramter im passing in when i ...
I have entity Unit and Tag, each with to-many relation to other. I am using NSFetchedResultsController to manage the data. What I need is to return distinct Unit object into NSFetchedResultsController for condition Tag.show == YES. I'm not sure how to feed all this to NSFetchedResultsController. Set entity to Unit or Tag, how to build ...
I have NSArray consisting of NSDictionary objects. Need to find index in NSArray of object with matching key name in NSDictionary. Dictionary has only 1 element. What is the fastest way of doing that? Filter with predicate and then use indexOfObject? ...
Hi everyone. I'am on a JSF problem using Nuxeo : I would like to get a predicate label (like "label.relation.predicate.inverse.Requires") out of this very predicate inside a JSF. I tried to do many things and all the objects I have are "statement" and "node". I tried to figure the label from the "#{statement.predicate.uri}" and wethe...
Lets say i have : Func<Customer,bool > a = (c) => c.fullName == "John"; now i want to convert to expressiontree any way to do that ? i know i can define it from the first place as expressiontree but the situation i have is different because i must concatenate some lambda expressions first then pass it to a method which take express...
Common LISP and Emacs LISP have the atom type predicate. Scheme and Clojure don't have it. http://hyperpolyglot.wikidot.com/lisp Is there a design reason for this - or is it just not an essential function to include in the API? ...
This site makes the following claim: http://hyperpolyglot.wikidot.com/lisp#ten-primitives McCarthy introduced the ten primitives of lisp in 1960. All other pure lisp functions (i.e. all functions which don't do I/O or interact with the environment) can be implemented with these primitives. Thus, when implementing or porting lisp, the...
I'm basically trying to do this, but I don't know what T will be, so I'm building things up using Reflection and Expression trees. // Input (I don't know about "Book") Type itemType = typeof(Book); // Actual Code // Build up func p => p.AuthorName == "Jon Skeet" ParameterExpression predParam = Expression.Parameter(itemType, "p"); Expre...
I have a ViewController whose view results from data from a fetch request with Predicate 1. I'd like to repeat the fetch request with a more restrictive Predicate 2 that will give a SUBSET of the data using Predicate 1. Then I'd like to update (and possibly animate) that view on the iPhone screen by pressing a toggle button, so that ...
I'm using C# and .NET 2.0. Given the XML below, I'd like to get a XMLNodeList of <user> nodes where the <role> is "admin". <users> <user> <name>John Doe</name> <roles> <role>superadmin</role> <role>admin</role> </roles> </user> <user> <name>Jane Doe</name> <rol...
Given this XML, I want to retrieve a XmlNodeList of <member> nodes from <group> nodes whose <id> matches 'Tech'. The matching should be case-insensitive. <groups> <group> <id>Tech</id> <members> <member>johndoe</member> <member>janedoe</member> <member>ro...
Can I pass additional parameters to a predicate function? I need it in a sorting process actually. public void Sort( Comparison<T> comparison ) where I would like to use Comparison predicate in this form: public delegate int Comparison<T>( T x, T y, object extraParameter ) Is this possible? Thanks, ...