In the Racket documentation, functions are also called procedures. A function that takes one argument and returns a Boolean (like even? or empty?) is often called a predicate. … A lambda without arguments that wraps an expression so it can be evaluated later is sometimes called a thunk.
Keeping this in consideration, how does if work in racket?
Conditionals in The Racket Guide introduces conditionals. Evaluates test-expr. If it produces any value other than #f, then then-expr is evaluated, and its results are the result for the if form. Otherwise, else-expr is evaluated, and its results are the result for the if form.
Furthermore, what is begin in racket?
Begin takes an arbitrary number of expressions and executes each one of them but only returns the result of the last expression in the body. https://stackoverflow.com/questions/29382733/racket-begin-form/29387064#29387064.
Why is it called a racket?
The French word requette means “palm of the hand,” and racquet originally referred to a tennis-like game played by hitting a ball with the hand.
In Racket (and other functional programming languages) lambda s are very useful, when you want to pass an in-line, one-shot function as a parameter without defining it first. For example, suppose that we want to square a list of numbers.
Chapter: Conditionals in Scheme
cond works by searching through its arguments in order. It finds the first argument whose first element returns #t when evaluated, and then evaluates and returns the second element of that argument. It does not go on to evaluate the rest of its arguments.
You can call a function in Racket by wrapping it in parentheses with the arguments after it. This looks like (function argument …) . Operations like + and * are functions as well, and they use the same syntax as calling f or g . For more information and examples, see Function Calls in the Racket Guide.
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.
Symbols in The Racket Guide introduces symbols. A symbol is like an immutable string, but symbols are normally interned, so that two symbols with the same character content are normally eq?. All symbols produced by the default reader (see Reading Symbols) are interned.
The quote form is more typically used for symbols and lists, which have other meanings (identifiers, function calls, etc.) when not quoted. and this shorthand is almost always used instead of quote. The shorthand applies even within the datum, so it can produce a list containing quote.
The first time you run DrRacket, you need to choose a programming language. Enter Ctrl-L to bring up the Choose Language dialog box. Select the language Pretty Big,a variant of Scheme, from the Legacy Languages list and click OK: After choosing the language, you can edit and evaluate expressions in DrRacket.