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Let's say that I create a vector/array in Scheme:
(let* ((x #(1 2 3)))
(list-ref x 0)) ; returns error
What syntax or function can I use in the place of that list-ref to get 1?
EDIT: I'm using Script-Fu with GIMP 2.8, where array-ref doesn't seem to work.
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vector::front() This function can be used to fetch the first element of a vector container.
Vectors are heterogenous structures whose elements are indexed by exact non-negative integers. A vector typically occupies less space than a list of the same length, and the average time required to access a randomly chosen element is typically less for the vector than for the list.
To remove first element of a vector, you can use erase() function. Pass iterator to first element of the vector as argument to erase() function.
The expression(define v '#(1 2 3)) is shorthand for creating a new vector, in standard Scheme it's equivalent to this:
(define v (list->vector '(1 2 3)))
Or this:
(define v (make-vector 3))
(vector-set! v 0 1)
(vector-set! v 1 2)
(vector-set! v 2 3)
Once a vector is created (using any of the mentioned procedures), the correct way to access an element in a vector is by calling the vector-ref procedure - clearly, because it's a vector and not a list of elements:
(vector-ref v 0)
In the previous expression, v is the vector and 0 the index whose element we want to retrieve. Take a look at the documentation for a more detailed explanation of the procedures outlined above.
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