Recent questions tagged Functional

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functional programming - How to test if two functions are the same?

I found a code snippet somewhere online: (letrec ([id (lambda (v) v)] [ctx0 (lambda (v) `(k ,v))] .... ... P.S. I use DrRacket to test the code. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - Scala Get First and Last elements of List using Pattern Matching

I am doing a pattern matching on a list. Is there anyway I can access the first and last element of the list to ... can I do that.. any Ideas? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - Scala: How to create a Map[K,V] from a Set[K] and a function from K to V?

What is the best way to create a Map[K,V] from a Set[K] and function from K to V? For example, suppose I have scala> ... 3 -> "33", 5 -> "55") See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - F# curried function

Anyone have a decent example, preferably practical/useful, they could post demonstrating the concept? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - What are the practical advantages of currying?

I see a lot of documentation and questions about what the currying technique is, but I have found very ... of work tinkering with languages. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - Feed elements of a tuple to a function as arguments in Haskell?

In my Haskell program, I want to use printf to format a list of tuples. I can map printf over a list ... tuple into two arguments for printf? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - How do I get the current time in Elm 0.17/0.18?

I had asked this question already: How do I get the current time in Elm? And answered it by writing my own (now ... on how I can clean this up? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - Underscores in a Scala map/foreach

Can you please help me understand what the underscore is doing in the second case ... .$read$$iw$$iw$$iw$$iw$$$Lambda$1197/562203102@a632ae0 See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - What are some uses of Clojure metadata?

How have you used metadata in your Clojure program? I saw one example from Programming Clojure: (defn shout [#^{ ... is completely new to me. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - Is there idiomatic C# equivalent to C's comma operator?

I'm using some functional stuff in C# and keep getting stuck on the fact that List.Add doesn't return the ... her nose at the code smell? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - Apply a list of Python functions in order elegantly

I have an input value val and a list of functions to be applied in the order: funcs = [f1, f2, f3 ... .com/function-composition-in-python/ . See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - When should I use function currying in Python?

When should I write my functions in curried form? does not match my thought, need to correct myself. As ... of variable number of arguments? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - Reverse a list in haskell

I am trying to reverse a list. Following is my code: reverseList :: [Int] -> [Int] reverseList [] = [] ... I did wrong here in this code. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - Motivation for Scala underscore in terms of formal language theory and good style?

Why is it that many people say that using underscore is good practice in Scala and makes your code more readable? ... good style to use it? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - Higher-order type constructors and functors in Ocaml

Can the following polymorphic functions let id x = x;; let compose f g x = f (g x);; let rec fix f = f (fix f) ... f x iso (Compose (Id a)) = a See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming: immutable data structure efficiency

I don't understand, how FP compilers make the code dealing with immutable data structures fast, not blow ... compilers actually optimize this ? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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529 views

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functional programming - Scala set function

In Stanford Scala course I've come across the following assignment: Exercise 1 - Sets as Functions: In this ... probably not the right way. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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611 views

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functional programming - Why does this Haskell code work successfully with infinite lists?

I have some Haskell code that does work correctly on an infinite list, but I do not understand why it can ... Please help me understand: why?? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - Why is the raising of an exception a side effect?

According to the wikipedia entry for side effect, raising an exception constitutes a side effect. Consider this simple ... not a pure function? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - any() function in Python with a callback

The Python standard library defines an any() function that Return True if any element of the iterable is true. If the ... , int) and e > 0) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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538 views

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functional programming - Idiomatic clojure for progress reporting?

How should I monitor the progress of a mapped function in clojure? When processing records in an imperative language ... the head for example.) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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501 views

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functional programming - How can I use map and receive an index as well in Scala?

Is there any List/Sequence built-in that behaves like map and provides the element's index as well? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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426 views

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functional programming - What is dependent typing?

Can someone explain dependent typing to me? I have little experience in Haskell, Cayenne, Epigram, or other ... I will appreciate it! See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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486 views

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functional programming - difference between foldLeft and reduceLeft in Scala

I have learned the basic difference between foldLeft and reduceLeft foldLeft: initial value has to be passed ... with similar functionality? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - Transform a Swift sequence in to adjacent pairs

Given I've got an array in Swift such as [1,2,3,4], a method pairs() will transform it in to the ... it can be used as flexibly as possible? See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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383 views

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functional programming - What are the uses of constructor reference in java 8

I was reading about Java 8 features, which lead me to this article and I was wondering about the actual uses of ... or tut it will be great See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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552 views

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functional programming - Flattening a List of Lists

I'm new to Scheme and functional programming in general. Can someone explain this code - specifically what ... sure about its functionality. See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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functional programming - Cartesian product in clojure

I'm trying to implement a method that will take a list of lists and return a the cartesian product of these ... wrong track. Please help! :) See Question&Answers more detail:os...

asked Oct 24, 2021 in Technique[技术] by 深蓝 (71.8m points)

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