Racket for the Masses

Math has no special representation nor it changes the way the code is normally evaluated.

So, this in most languages:

1 + 2 + 3 * 4 * 5

Is written in Racket like this:

(+ 1 2 (* 3 4 5))

Other languages have “commands”, reserved words, and special syntaxes for control structures. There is no such things in Racket. For example, if is usually reserved in other languages and have a special structure:

In Ruby, it is:

if a == b
  1
else
  2
end

Or in Javascript:

a === b ? 1 : 2;

The equivalent in Racket is:

(if (= a b) 1 2)

Note that it looks exactly like a function call.

A variable assignment (called binding in Racket) usually has a special structure in other languages. In Racket they look like functions, as everything else.

Variable assignment in Ruby:

a = 1

In Racket:

(define a 1)

Any other language have well defined syntaxes and reserved keywords for defining functions, methods, classes and so on.

For example, a function in Python is defined like this:

def add1(a):
    return a + 1

add1(10)

In Racket, defining a function looks like we are just calling the function define:

(define (add1 a) (+ a 1))
(add1 10)

Anonymous functions or code block in other languages also have special syntaxes. For example, a code block in Ruby looks like this:

add1 = -> a { a + 1 }
add1[10]

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In Racket they still look like functions:

(define add1 (lambda (a) (+ a 1)))
(add1 10)

Or using the character “λ” instead of the word “lambda”.

(define add1 (λ (a) (+ a 1)))
(add1 10)

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However, for simple functions like that, it is common to just use currying.

(define add1 (curry + 1))
(add1 10)

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Given that the syntax for functions and everything else looks exactly the same, we need a name for them. In Racket they are called forms.