Predeclared in LISTS

Applies binary function f to the elements of xs from right-to-left order, first applying f to the last element and the value initial, resulting in r₁, then to the second-last element and r₁, resulting in r₂, etc, and finally to the first element and r_n-1, where n is the length of the list. Thus, accumulate(f,zero,list(1,2,3)) results in f(1, f(2, f(3, zero))). Iterative process; time: O(n), space: O(n), where n is the length of xs assuming f takes constant time.

Returns a list that results from appending the list ys to the list xs. Iterative process; time: O(n), space: O(n), where n is the length of xs. In the result, null at the end of the first argument list is replaced by the second argument, regardless what the second argument consists of.

Makes a list with n elements by applying the unary function f to the numbers 0 to n - 1, assumed to be a nonnegative integer. Iterative process; time: O(n), space: O(n).

Optional second argument. Similar to display, but formats well-formed lists nicely if detected.

visualizes x in a separate drawing area in the Source Academy using a box-and-pointer diagram; time, space: O(n), where n is the total number of data structures such as pairs in all the separate structures provided in x.

Returns a list that enumerates numbers starting from start using a step size of 1, until the number exceeds (>) end. Iterative process; time: O(n), space: O(n), where n is end - start.

Returns true if both have the same structure with respect to pair, and identical values at corresponding leave positions (places that are not themselves pairs), and false otherwise. For the "identical", the values need to have the same type, otherwise the result is false. If corresponding leaves are boolean values, these values need to be the same. If both are undefined or both are null, the result is true. Otherwise they are compared with === (using the definition of === in the respective Source language in use). Time, space: O(n), where n is the number of pairs in x.

Returns a list that contains only those elements for which the one-argument function pred returns true. Iterative process; time: O(n), space: O(n), where n is the length of xs.

Applies unary function f to every element of the list xs. Iterative process; time: O(n), space: O(1), Where n is the length of xs. f is applied element-by-element: for_each(fun, list(1, 2)) results in the calls fun(1) and fun(2).

returns head (first component) of given pair p

Returns true if xs is a list as defined in the textbook, and false otherwise. Iterative process; time: O(n), space: O(1), where n is the length of the chain of tail operations that can be applied to xs. recurses down the list and checks that it ends with the empty list null

returns true if x is the empty list null, and false otherwise.

returns true if x is a pair and false otherwise.

Returns the length of the list xs. Iterative process; time: O(n), space: O(1), where n is the length of xs.

Given n values, returns a list of length n. The elements of the list are the given values in the given order.

Returns the element of list xs at position n, where the first element has index 0. Iterative process; time: O(n), space: O(1), where n is the length of xs.

Returns a string that represents list xs using the text-based box-and-pointer notation [...].

Returns a list that results from list xs by element-wise application of unary function f. Iterative process; time: O(n), space: O(n), where n is the length of xs. f is applied element-by-element: map(f, list(1, 2)) results in list(f(1), f(2)).

Returns first postfix sublist whose head is identical to v (using ===); returns null if the element does not occur in the list. Iterative process; time: O(n), space: O(1), where n is the length of xs.

makes a pair whose head (first component) is x and whose tail (second component) is y.

Returns a list that results from xs by removing the first item from xs that is identical (===) to v. Returns the original list if there is no occurrence. Iterative process; time: O(n), space: O(n), where n is the length of xs.

Returns a list that results from xs by removing all items from xs that are identical (===) to v. Returns the original list if there is no occurrence. Iterative process; time: O(n), space: O(n), where n is the length of xs.

Returns list xs in reverse order. Iterative process; time: O(n), space: O(n), where n is the length of xs. The process is iterative, but consumes space O(n) because of the result list.

returns tail (second component of given pair p