Sequence

The head Sequence is rarely seen in directly. Consider the function (f)

below, where the first two arguments are p1,and p2, and all the remaining

arguments are part of p3. All the remaining arguments go with p3 because the

definition of (f) uses BlankSequence (___) for p3. The only thing the

function (f) does is return p3. One might wonder what head is given to p3.

It turns out it is given the head Sequence. After (f) is defined, we use it

to make the Sequence (seq).

If you have a number of sequences inside almost any head the sequences are automatically flattened, and the fact that the arguments are a sequence is not indicated (see the example in the next line). The only functions that don't splice the sequences together are those with the Attribute SequenceHold.

Most useful applications of Sequence are variations of the next cell where

the head (h) is changed to Sequence and the effect is that h[7,11,13] is

changed to (7,11,13).

Created by Mathematica (May 16, 2004)