= Sequences =

It would be convenient for CIVL-C to have a sequence type.  This avoids the array/pointer conversions in C, allows sequences to be passed around by value, and allows for standard sequence operations.

* `$seq<T>`
 * a sequence of elements of type T
* `int $seq_length($seq<T>)`
 * returns the number of elements in this sequence
* `$seq<T> $seq_concat($seq<T>, $seq<T>)`
 * returns the concatenation of two sequences
* `$seq<T> $seq_add($seq<T> a, T x)`
 * returns the result of adding the element `x` to the sequence `a`
* `$seq<T> $seq_remove($seq<T> a, int i)`
 * returns the result of removing the element at index `i` from the sequence `a`
* `$seq<T> $seq_subseq($seq<T> a, int start, int end)`
 * returns the subsequence of `a` starting at index `start` and ending at index `end`
* `$seq<T> $seq_write($seq<T> a, int i, T x)`
 * returns the sequence obtained by replacing the element of `a` at index `i` with `x`
* `T $seq_read($seq<T> a, int i)`
 * returns the element of `a` at index `i`