standard-library-functions.md

Standard Library Functions

abs

Returns the absolute value of a number.

(abs -1) -> 1
(abs 0)  -> 0
(abs +1) -> 1

and

Takes two conditions. Returns true if both conditions evaluate to true and false otherwise.

(if (and (ge x 13) (le x 19))
    {print "x is in the teens"}
    {print "x is not in the teens"}
)

any

Takes a function and an array. Returns true if the function returns true for any element of the array.

(any is-odd {2 3 4}) -> true

cube

Returns the cube of a number.

(cube 3) -> 27

every

Takes a function and an array. Returns true if the function returns true for every element of the array.

(every is-even {2 4 6}) -> true

factorial

Returns the factorial of a number.

(factorial 5) -> 120

filter

Takes a function and an array. Returns the elements of the array for which the function returns true.

(filter is-odd (range 5)) -> {1 3 5}

first

Returns the first element of an array.

(first {a b c}) -> a

foreach

Similar to the map function. The only difference is that the array comes first and the function comes second.

(foreach (range 3) square) -> {1 4 9})

fun

Provides a shortcut for defining named functions compared to using the def function. The fun function takes two arguments. The first argument is the prototype of the function, which is an array of symbols containing the name of the function followed by the names of the parameters. The second argument is the quoted body of the function.

(fun {square x} {mul x x})

[ equivalent function definition using the `def` function ]
(def {square} (lambda {x} {mul x x}))

ge

Takes two numbers. Returns true if the first number is greater than or equal to the second number and false otherwise.

(ge 1 2) -> false
(ge 2 2) -> true
(ge 3 2) -> true

head

Takes an array and returns a slice containing only the first element of the array.

(head {a b c}) -> {a}

is-empty

Takes an array and returns true if the array is empty and false otherwise.

(is-empty {}) -> true
(is-empty {a b c}) -> false

is-even

Takes a number and returns true if the number is even and false otherwise.

(is-even 1) -> false
(is-even 2) -> true

is-odd

Takes a number and returns true if the number is odd and false otherwise.

(is-odd 1) -> true
(is-odd 2) -> false

last

Returns the last element of an array.

(last {a b c}) -> c

le

Takes two numbers. Returns true if the first number is less than or equal to the second number and false otherwise.

(le 1 2) -> true
(le 2 2) -> true
(le 3 2) -> false

map

Takes a function and an array. Applies the function to every element of the array and returns an array containing the results.

(map square (range 3)) -> {1 4 9}

ne

Takes two arguments. Returns true if the arguments are not equal and false otherwise.

(ne 1 0) -> true

not

Takes a boolean and returns the opposite value.

(not true) -> false
(not false) -> true

or

Takes two conditions. Returns true if either condition evaluates to true and false otherwise.

(if (or (gt x 0) (lt x 0))
    {print "x is nonzero"}
    {print "x is zero"}
)

product

Returns the product of an array of numbers.

(product {2 3 5}) -> 30

range

Takes a number and returns an array of numbers from 1 to that number.

(range 3) -> {1 2 3}

reduce

Takes a function, an array, and an accumulator. Applies the function against the accumulator and each element of the array to reduce the array to a single value.

(reduce add {1 2 3} 0) -> 6

[ equivalent expression ]
(add (add (add 0 1) 2) 3) -> 6

reverse

Reverses an array.

(reverse {a b c}) -> {c b a})

square

Returns the square of a number.

(square 3) -> 9

sum

Returns the sum of an array of numbers.

(sum {2 3 5}) -> 10

tail

Takes an array and returns a slice containing all but the first element of the array.

(tail {1 2 3}) -> {2 3}