In general, I think verbs should be avoided, when possible, as names of functional operations. For instance, in Java, 'BigInteger.add' should have been 'plus'. Compare:
x.add(y);
x.plus(y);
People have been known to write the first one expecting 'x' to be updated. With the second, I think it's clearer that it's a value that needs to be assigned to a variable.
For the operation in question here, I suggest 'with'. This is what I have used in my own functional collections libraries; I think it originated in SETL.
For the operation in question here, I suggest 'with'. This is what I have used in my own functional collections libraries; I think it originated in SETL.