Repetition in functional languages ↩

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created: 2022-07-24 22:09:19
modified: 2022-07-24 22:18:19

In functional languages, new values are associated with new names through recursive functions call nesting.

in functional programming languages, the same names cannot be reused with different values

nested function calls are used to create new versions of the names for new values
since there is no command repetition permitted (like in imperative languages), recursive function calls are used are used to repeatedly create new versions of names associated with new values

Example

To sum an array, we can use the following function:

FUNCTION SUM(A:ARRRAY [1..N] OF INTEGER; I,N:INTEGER):INTEGER;
BEGIN
    IF I > N THEN
        SUM := 0
    ELSE
        A[I] + SUM(A,I+1,N)
END

Here, each recursive call to SUM creates new local versions of A, I and N and the previous versions become inaccessible.