# What is pair in racket?

Pairs and Lists in The Racket Guide introduces pairs and lists. A pair combines exactly two values. The first value is accessed with the car procedure, and the second value is accessed with the cdr procedure. Pairs are not mutable (but see Mutable Pairs and Lists).

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## Keeping this in view, what does pair do in Scheme?

Pairs are used to combine two Scheme objects into one compound object. Hence the name: A pair stores a pair of objects. The data type pair is extremely important in Scheme, just like in any other Lisp dialect.

Correspondingly, what is pair in Lisp? An association list, or a-list, is a data structure used very frequently in Lisp. An a-list is a list of pairs (conses); each pair is an association. The car of a pair is called the key, and the cdr is called the datum. … Other variants of a-list searches can be constructed using the function find or member.

## Besides, is a Pair a list Scheme?

(1 2) represented in dot form may be written (1 2 . NIL) , but you should not write something like this. “A list is a combination of pairs that creates a linked list. More precisely, a list is either the empty list null, or it is a pair whose first element is a list element and whose second element is a list.”

## What is map in racket?

The map function walks a list (or multiple lists), and applies a given function to every value of a list. For example mappiing add1 to a list results in: > (map add1 ‘(1 2 3 4)) ‘(2 3 4 5)

## What is pair in C++?

The pair container is a simple container defined in <utility> header consisting of two data elements or objects. The first element is referenced as ‘first’ and the second element as ‘second’ and the order is fixed (first, second). … Pair provides a way to store two heterogeneous objects as a single unit.

## What things go together in pairs?

Matching Word Pairs

• Salt and Pepper.
• Peanut Butter and Jelly.
• Red Beans and Rice.
• Macaroni and Cheese.
• Bacon and Eggs.
• Bonnie and Clyde.
• Batman and Robin.
• Mickey and Minnie.

## What is list Why list can be called as pair?

List is constructed by placing expressions within square brackets separated by commas. Example for List is [10, 20], The elements of a list can be accessed in two ways. … Lists are a common method to do so. Therefore List can be called as Pairs.

## What does let do in racket?

Local Binding: let, let*, letrec, … in The Racket Reference also documents let. A let form binds a set of identifiers, each to the result of some expression, for use in the let body: (let ([id expr] …) body …+)

## What is Cond Lisp?

COND. COND is an unusual function which may take any arbitrary number of arguments. Each argument is called a clause, and consists of a list of exactly two S-expressions. We will call the first S-expression in a clause a condition, and the second S-expression a result.

## How do you make a pair in Kotlin?

In Kotlin, constructor is a special member function that is invoked when an object of the class is created primarily to initialize variables or properties. To create a new instance of the Pair we use: Pair(first: A, second: B)

## How do you define a list in LISP?

The list function is rather used for creating lists in LISP. The list function can take any number of arguments and as it is a function, it evaluates its arguments. The first and rest functions give the first element and the rest part of a list.