grammar - Meaning of "I would there were..."?

What is the meaning of "I would there were", as in this quote from Shakespeare's "A Winter's Tale"?

I would there were no age between sixteen and three-and-twenty, or
that youth would sleep out the rest;

From its context, I assume it means "I wish there were" but I find it difficult to conceive how the modern usage of "would" could ever have been used in this way.

Answer

It simply means “I wish” or “O that”. Even today some people will still say “Would that it were so!” in an intentionally archaic manner.

See sense 36 of the OED entry on will. This is just an excerpt:

36. Similarly with const. as in 2: viz. with obj. clause, with vb. in past subj. (arch. except in would rather or sooner = ‘should prefer’), †rarely in pres. subj., or with acc. and inf. Hence (arch.) with ellipsis of 1st pers. pron. as an expression of longing = ‘I wish’, ‘O that’; also, by confusion with 37, in the form (I) would to God (or heaven).

• 1590 Shaks. Mids. N. v. i. 255, ― I am wearie of this Moone; would he would change.


• 1595 Shaks. John iii. iv. 48, ― I am not mad, I would to heauen I were.


• 1599 B. Jonson Cynthia’s Rev. To Rdr. A 4 b, ― I would thou hadst some Sugar Candyed, to sweeten thy Mouth.


• 1777 Miss M. Townshend in Jesse Selwyn & Contemp. (1844) III. 260 ― This news I picked up at Bet’s door. Would to God that we had peace!


• 1816 J. Wilson City of Plague ii. i, ― At a sad hour the sailor hath return’d; Would he were yet at sea!



• 1831 Scott Ct. Rob. xix, ― I would to God I had more.


• 1865 Whittier Kallundborg Church 48 ― Would I might die now in thy stead!


• 1882 Tennyson Charge of the Heavy Brigade Epil. 10-11, ― I would that wars should cease, I would the globe from end to end Might sow and reap in peace.