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What is nil and cons?
Nil: The empty list. Cons: A cell containing an element also known as head; and a pointer to the rest of the list also known as tail. The term cons comes form functional programming language ‘lisp’. In Scala, there is a double colon operator :: called cons operator.
What does cons stand for in Lisp?
In computer programming, cons (/ˈkɒnz/ or /ˈkɒns/) is a fundamental function in most dialects of the Lisp programming language. cons constructs memory objects which hold two values or pointers to values. These objects are referred to as (cons) cells, conses, non-atomic s-expressions (“NATSes”), or (cons) pairs.
Are lists efficient Python?
So if you’re creating a few tuples and accessing them many many times, it may actually be faster to use lists instead. Of course if you want to change an item, the list will definitely be faster since you’d need to create an entire new tuple to change one item of it (since tuples are immutable).
What does cons mean in scheme?
The primitive procedure cons means “construct.” Cons takes two arguments and returns a list constructed from those two arguments. In this capacity, it provides a means of combination for the Scheme programming language. Note In programming languages, a constructor creates a new object, such as a list object.
What is the difference between cons and list?
A cons is a record structure containing two components called the car and the cdr. A list is recursively defined to be either the empty list or a cons whose cdr component is a list. A list is therefore a chain of conses linked by their cdr components and terminated by nil, the empty list.
What are pro and cons?
1 : arguments for and against —often + of Congress weighed the pros and cons of the new tax plan. 2 : good points and bad points Each technology has its pros and cons.
Which is faster tuple or list in Python?
Tuple has a small memory. Creating a tuple is faster than creating a list. Creating a list is slower because two memory blocks need to be accessed. An element in a tuple cannot be removed or replaced.
Does car return a list scheme?
The valid indexes of a list are the exact non-negative integers less than the length of the list. The first element of a list has index 0 , the second has index 1 , and so on. (list-ref list k ) is equivalent to (car (list-tail list k )) . Returns the specified element of list .
What is a dotted pair?
Dotted pair notation is a general syntax for cons cells that represents the CAR and CDR explicitly. In this syntax, ( a . b ) stands for a cons cell whose CAR is the object a and whose CDR is the object b . Dotted pair notation is more general than list syntax because the CDR does not have to be a list.
What is full form of pros and cons?
The phrase ‘pros and cons’ is an abbreviation of the Latin phrase pro et contra, ‘for and against’, and has been in use in the abbreviated form since the 16th century, according to the Oxford English Dictionary. The much longer alternative is the phrase ‘arguments for and against’.
What is a pros and cons list called?
A pros and cons list is a simple but powerful decision-making tool used to help understand both sides of an argument. Pros are listed as arguments in favor of making a particular decision or action. Cons are listed arguments against it.