How does append work Scheme?

How does append work Scheme?

The append function joins two lists together to make one. The append function is built into Scheme. It concatenates two lists, that is to say, given two lists list1 and list2 it produces a new list which starts with the same elements as list1 and finishes with those of list2 .

What is the meaning of the URL Scheme?

Custom URL schemes provide a way to reference resources inside your app. Users tapping a custom URL in an email, for example, launch your app in a specified context. Other apps can also trigger your app to launch with specific context data; for example, a photo library app might display a specified image.

How does reverse work in Scheme?

reverse takes a list and returns a new list, with the same elements but in the opposite order. Note that like most Scheme procedures, neither of these procedures is destructive–each creates a new list without side-effecting (modifying) its argument(s).

What is a URL vs URI?

URL is used to describe the identity of an item. URI provides a technique for defining the identity of an item. URL links a web page, a component of a web page or a program on a web page with the help of accessing methods like protocols. URI is used to distinguish one resource from other regardless of the method used.

What is URL scheme iOS?

The URL scheme is an interesting feature provided by the iOS SDK that allows developers to launch system apps and third-party apps through URLs. You can use a specific URL scheme to launch the built-in phone app and dial the number automatically.

What does CDR mean in racket?

In computer programming, CAR ( car ) /kɑːr/ ( listen) and CDR ( cdr ) (/ˈkʌdər/ ( listen) or /ˈkʊdər/ ( listen)) are primitive operations on cons cells (or “non-atomic S-expressions”) introduced in the Lisp programming language.

What is null in Scheme?

In Scheme, there is one null pointer value, called “the empty list,” which prints as () . Conceptually, the empty list is a special object, and a “null” pointer is a pointer to this special end-of-list object.

What is fold Scheme?

You can think of the fold as taking the function and putting it between each element in the list: (foldr + 0 ‘(1 2 3)) is the same as 1 + 2 + 3 + 0 . Fold is special because, unlike the other two, it usually returns a scalar value–something that was the element of the list rather than the list itself.