Chiasmus is a literary technique that was common in ancient Greek writings, including the New Testament. Basically, chiasmus takes the form ABBA. An example in English is a familiar nursery rhyme:
A: The itsy-bitsy spider went up the water spout.
B: Down came the rain and washed the spider out.
B: Up came the sun and dried up all the rain.
A: And the itsy-bitsy spider went up the spout again.
Chiasms can be much larger and have more elements. Entire literary works sometimes take the form of a chiasm. The chiastic structure may have been an aid to memorization. Sometimes a chiasm may have been intended to emphasize its central element. The form ABCBA puts emphasis on C. The elements A and B form a frame.
I know a lot more about Greek than I do about Hebrew, but I think that chiasms may also be found in ancient Hebrew literature.
If you are looking for hope in the book of Lamentations, it is only to be found in the central verses of chapter 3, the central chapter. Whether this is intended to emphasize the message of hope, I'm not in a position to say. The rest of the book may frame this expression of hope or, alternatively, they may bury it. The New Interpreters Study Bible suggests that this chapter may serve as "a kind of abstract reflection on the catastrophe" of Jerusalem's fall and the exile.
Lamentations 3:22-23 is the inspiration for the favorite old hymn Great is Thy Faithfulness:
Because of the Lord’s great love we are not consumed,
for his compassions never fail.
They are new every morning;
great is your faithfulness.
The words sound very different in their original context than on most of the Sunday mornings when we sing them.
Verses 32-33 are, for this book, a powerful statement of faith:
Though [YHWH] brings grief, he will show compassion,
so great is his unfailing love.
For he does not willingly bring affliction
or grief to anyone.
There might be a little bit of the victim's self-blame in that. But to say, while remembering the horrors of the siege and destruction of Jerusalem, God "does not willingly afflict anyone" is remarkable.
Counting on YHWH's good will and faithfulness, verses 40-42 counsel repentance:
Let us examine our ways and test them,
and let us return to the Lord.
Let us lift up our hearts and our hands
to God in heaven, and say:
“We have sinned and rebelled
and you have not forgiven.”
Chapter 3 ends with a plea for vengeance (v.v. 64-66):
Pay them back what they deserve, Lord,
for what their hands have done.
Put a veil over their hearts,
and may your curse be on them!
Pursue them in anger and destroy them
from under the heavens of the Lord.
Chapter 4 bemoans the state to which Jerusalem's noble people were reduced:
With their own hands compassionate women
have cooked their own children,
who became their food
when my people were destroyed.
Once again responsibility is laid squarely on YHWH's shoulders:
The Lord has given full vent to his wrath;
he has poured out his fierce anger.
He kindled a fire in Zion
that consumed her foundations.
Verse 13 explains, once more, the reason for YHWH's anger:
But it happened because of the sins of her prophets
and the iniquities of her priests,
who shed within her
the blood of the righteous.
Verses 21-22 warn Judah's neighbor Edom not to gloat. Jerusalem will be restored but Edom will go down.
Chapter 5 is the only poem of Lamentations which is not structured as an alphabetic acrostic. It catalogs the degradations suffered by Judah's people including rape and torture:
Women have been violated in Zion,
and virgins in the towns of Judah.
Princes have been hung up by their hands....
The book ends with a plea for the eternal God to remember Zion and restore his people (vv. 19-21). Its final verse plays with the haunting possibility that this may never be:
...unless you have utterly rejected us
and are angry with us beyond measure.
Biblical quotations are from the New International Version. Next: Ezekiel 1-4