The lambda tag has no usage guidance.
-2
votes
0answers
16 views
Spark SQL as serving layer
I am about to design a Big data project.
In the project, massive data will be stored to HDFS that will be our batch layer.
Then we will build some batch view using Spark Sql.
Now, the main open point ...
1
vote
0answers
79 views
Designing large nanoservice architecture with AWS Lambdas
I'm moving from a coupled architecture to a decoupled architecture using microservices with AWS Lambda.
Here is my current architecture:
Each API Gateway route is linked to a specific Lambda, each ...
0
votes
3answers
280 views
Efficiency of nameless functions
The current trend seems to be to use lambda type function in languages that can take that syntax. Is this just a trendy thing or is actually more efficient? eg in javascript, you can get stuff like
...
7
votes
2answers
211 views
In Java 8, is it stylistically better to use method reference expressions or methods returning an implementation of the functional interface?
Java 8 added the concept of functional interfaces, as well as numerous new methods that are designed to take functional interfaces. Instances of these interfaces can be succinctly created using ...
6
votes
3answers
204 views
Server architecture for short bursts of ~150 parallel CPU-heavy subqueries
The client sends a query (a few hundred characters) to the web service. This query can be split into 20 to 150 subqueries with a simple regex. Those subqueries can then be computed independently and ...
2
votes
2answers
135 views
Unknown number of arguments in currying
Hypothetical situation - can a currying function have an unknown number of arguments (kind of like varargs)
Eg in Python:
addByCurrying(1)(2)(3)(4)
Should equal 10
addByCurrying(5)(6)
Should ...
4
votes
2answers
129 views
Serverless architecture: How to deploy changes in common business logic?
I've been hearing lately more and more about serverless architectures which are based on products such as AWS Lambdas, Azure Functions, Google Cloud Functions, etc.
I understand the advantages of ...
7
votes
0answers
426 views
What lambda function optimizations, if any, are planned for Java 9 and beyond? [closed]
I'm working on a high-performance project where Java 8's lambda functions are enormously useful. I've found, however, that they're memory inefficient when used en masse. For example, suppose I need to ...
0
votes
1answer
161 views
Most elegant way to execute a AWS lambda function with preloaded parameters on a specific time
I am looking for the following workflow:
Add an entry to a table of my Postgres database with a end_date and state (with the following values: active or done) columns.
Execute a lambda at the exact ...
0
votes
2answers
84 views
Lambda calculus: Call by value / Call by name (lazy)
Having difficulties deciding which rules to apply on by value / by name evaulation.
Say I have:
(λz.zz)(λb.b)
And I want to evaluate according to call by valute, will the next step be
(λz.z)(λb.b)...
0
votes
1answer
71 views
How confusing is `new SomeCollection(values…)::contains` as a Predicate? [closed]
Traditionally, a function that want to skip certain items during processing will accept a Collection or var-args argument, but in the Java 8 world I think I should switch to Predicates.
Now, since ...
0
votes
1answer
126 views
Specifying a default value for an optional anonymous function parameter in VB.NET
I'm considering a class that uses a generic type (though this isn't directly important to the question here) and allows the user to specify an optional "strategy" function when instantiating a class ...
2
votes
2answers
381 views
Java - Using a Function variable to set the toString() method's return value
Lately I've started adding this to certain classes in an in-house API:
public class MyClass {
// I usually do this with classes I expect to
// be printed out or tested a lot (particularly
// ...
25
votes
3answers
5k views
Why should I use “functional operations” instead of a for loop?
for (Canvas canvas : list) {
}
NetBeans suggests me to use "functional operations":
list.stream().forEach((canvas) -> {
});
But why is this preferred? If anything, it is harder to read and ...
5
votes
1answer
139 views
C++11 Lambda vs Helper Member Functions
There are a bunch of methods in a class that I want to clean up. These just build up a data structure (with different values) over and over again and add them to a container passed in, like so:
...
10
votes
1answer
2k views
Java 8: Good practice to pass Streams around in APIs for lazy operations?
In pre-Java 8 lambda-heavy libraries like Guava, the outputs use common Java Collection Framework interfaces so is easy to pass them around to external/internal APIs and still harness some lazy ...
4
votes
1answer
442 views
Lambda Return Type Inference
Writing my own JVM compiler, I am facing a giant problem that I am desperately unable to solve:
Lambda Return Type Inference
1. Overview of the compiler lifecycle
More specifically, the order in ...
36
votes
4answers
5k views
Is there a performance benefit to using the method reference syntax instead of lambda syntax in Java 8?
Do method references skip the overhead of the lambda wrapper? Might they in the future?
According to the Java Tutorial on Method References:
Sometimes... a lambda expression does nothing but call ...
2
votes
2answers
239 views
Functional Programming style: How to write functions - explicit currying, implicit currying or lamdas?
So I have been using F# for a while and studying a bit of Haskell on the side and I have realized I could rewrite the exact same function one of three different ways.
Either with implicit currying, ...
0
votes
2answers
77 views
Iterating a function with a static argument: Global functions + lambdas vs internal function?
I am never sure which of these is better form:
Option A
def a(x,y):
def b(z): return z+y
return map(b, x)
print a([10,20], 5)
Option B
def b(z,y): return z+y
def a(x,y):
return map(...
13
votes
2answers
2k views
Is this a good pattern: replacing a long function with a series of lambdas?
I recently run into the following situation.
class A{
public:
void calculate(T inputs);
}
Firstly, A represents an object in the physical world, which is a strong argument for not splitting the ...
4
votes
3answers
4k views
Lambda expressions with no parameters in Haskell and / or lambda calculus
In eager languages like Scheme and Python, you can use a lambda expression without parameters to delay evaluation, e.g. in Scheme (Chicken Scheme):
#;1> (define (make-thunk x) (lambda () (+ x 1)))
...
5
votes
3answers
348 views
Does it make sense to split up an existing multi-method interface into several single method interfaces just to take advantage of lambdas?
Say I have an existing callback interface that has multiple methods. To illustrate my point I use a callback the likes that you would see in code that performs some HTTP client operations:
public ...
0
votes
2answers
792 views
Handling multiple packet types in Java 8
I have a Netty-based game server implementation that handles 40 or so distinct packets with their own serialization structure, for brevity I'll refer to them as FooPacket, BarPacket, ... These packet ...
4
votes
1answer
733 views
Is Lambda Still Supported In Python?
Only one or two years ago, I remember reading Python constructs that would be removed from Python -- reduce was one of them -- and other constructs that would be emphasized like comprehensions and ...
5
votes
1answer
973 views
Is the Fork/Join framework a bad match for the Java 8 Streams API?
Today I found an article about Java8's Fork/Join-Framework and its usage for the parallel streams implementation. While I do understand the article, I'm not entirely sure what I should think of it.
...
1
vote
2answers
687 views
Using Statement lambda in exception handling
Following is a code snippet from MVP Win Forms application and this explanation would be helpful when answering the questions.
My DAL doesn't handle exceptions and it will be propagated up to the ...
1
vote
2answers
263 views
How the Stream.filter() method works?
I know how the lambda expresion works and I know it is an argument for .filter() that establish the criteria to filter with. But I don't get how .filter() uses the argument, in this case a lambda ...
3
votes
3answers
930 views
If Scheme is untyped, how can it have numbers and lists?
Scheme is said to be just an extension of the Untyped Lambda Calculus (correct me if I am wrong). If that is the case, how can it have Lists and Numbers? Those, to me, look like 2 base types. So I'd ...
0
votes
2answers
36k views
foreach in list or foreach in list.where [duplicate]
I don't know what to call this question.
This is my example:
foreach (var item in lstItem.Where(item => stock.ItemCode == item.ItemCode))
{
stock.ItemName = item.ItemName;
stock....
6
votes
1answer
2k views
Redex and reduction strategies
I'm studying Types and Programming Languages, and have some trouble getting my head around the concepts of the 5th chapter, The Untyped Lambda Calculus.
Specifically, redex, reduction and the various ...
1
vote
1answer
341 views
Is there any practical algorithm / data-structure that can't be done with non-recursive Lambda Calculus augmented with foldl?
In my search for a practical non-turing complete programming language, I've been paying attention to lambda-calculus with disallowed self-application - that is, x x forbidden. After taking that ...
5
votes
3answers
369 views
Interface at the class or function level?
I have been falling into a pattern lately where I have been defining routines that rely on an interface defined by a function that is specified as a parameter to the routine. (The language is C#, but ...
0
votes
1answer
794 views
Techniques to Enable Dynamic Query / Calculation at Runtime
I'm working on a C# project which provides users an on-demand method of importing data from various formats and then performs mail-merge-like actions to complete a template. The process works for ...
3
votes
1answer
1k views
How to serialize and deserialize lambda expression in F#?
I serialized lambda expressions in C# before. Now I wanna use F# instead of C# for serialization and deserialization.
I heard F# is better in this area. Is it true?
How can I do that with F#?
I’d ...
4
votes
1answer
2k views
Untyped lambda calculus: Why is call-by-value strict?
I'm currently reading Benjamin C. Pierce's “Types and Programming Languages”. Before really getting into type theory it explains lambda calculus and evaluation strategies.
I am a bit confused by the ...
14
votes
5answers
909 views
What is the name of λx.λf.fx (like reverse apply) in lambda calculus? Does the corresponding function have a standard name in programming?
What is the name of λx.λf.fx in lambda calculus?
Does the corresponding function have a standard name in functional programming languages, like Haskell?
In object oriented programming, is there a ...
29
votes
5answers
13k views
Is a lambda expression something more than an anonymous inner class with a single method?
There is a new hype with the long awaited lambda expressions in Java 8; every 3 day another article appears with them about how cool they are.
As far as I have understood a lambda expression is ...
8
votes
1answer
1k views
Are “normal order” and “call-by-name” the same thing?
I was studying the book Structure and Interpretation of Computer Programs and in section 1.1.5 The Substitution Model for Procedure Application the author explains the concepts of normal order and ...
10
votes
4answers
1k views
What is Java's primary focus? Why does it take so long to get new features?
I have been exploring the new features in the JDK8, like the lambda expressions, the extension methods, and the new stream API.
Evidently none of these features are new in the programming world and ...
4
votes
1answer
486 views
How to properly diagram lambda expressions or traversals through them in Architecture Explorer?
I'm exploring a piece of code in Architecture Explorer in Visual Studio 2010 to study the relations between methods. I noticed a strange behavior.
Take the following source code. It generates a hello ...
5
votes
1answer
192 views
Lambda Calculus Free Variable
Here's something from Slonneger's "Syntax and Semantics of Programming Languages":
A variable may occur both bound and free in the same lambda
expression: for example, in λx.yλy.yx the first ...
2
votes
1answer
2k views
Is python lambda “really formal” λ-calculus or just share the name?
Now and then I use the Python lambda. Is it so formal that it is safe to say that you can do formal lambda calculus with it? I just used it but I didn't fully understand whether the python lambda and ...
5
votes
4answers
12k views
What does this mean: Expression<Func<TModel, TValue>>
In ASP.Net MVC, in the razor view, you can type this kind of code:
@Html.EditorFor(model => model.Name)
(in this case, it creates a textbox for the field Name of the object which is defined as ...
18
votes
1answer
1k views
Why doesn't Haskell have type-level lambda abstractions?
Are there some theoretical reasons for that (like that the type checking or type inference would become undecidable), or practical reasons (too difficult to implement properly)?
Currently, we can ...
26
votes
1answer
12k views
Type inference in Java 8
Is the introduction of the new lambda notation (see e.g. this article) in Java 8 going to require some kind of type inference?
If so, how will the new type system impact the Java language as a whole?
98
votes
14answers
19k views
What triggered the popularity of lambda functions in modern mainstream programming languages?
In the last few years anonymous functions (AKA lambda functions) have become a very popular language construct and almost every major / mainstream programming language has introduced them or is ...
11
votes
1answer
7k views
C++11 support for higher-order list functions
Most functional programming languages (e.g. Common Lisp, Scheme / Racket, Clojure, Haskell, Scala, Ocaml, SML) support some common higher-order functions on lists, such as map, filter, takeWhile, ...
5
votes
3answers
796 views
What can procs and lambdas do that functions can't in ruby
I've been working in Ruby for the last couple weeks, and I've come to the subject of procs, lambdas and blocks. After reading a fair share of examples from a variety of sources, I don't how they're ...
39
votes
4answers
10k views
C is written in C, how is this possible? [duplicate]
Possible Duplicate:
How could the first C++ compiler be written in C++?
I know my question goes to the underground galaxy cave where languages are born and involves some lambda math and light-...
