[851] The Law of the Light and the Law of the Darkness

7 forming [rc,yE] light, and creating [ar"B'] darkness; making [hf'[] peace, and creating [ar"B] evil. I, , do [hf'['] all these things. (Isaiah 45 )

rc,yE to form or formulate ar"B' to carve out or separate from hf'[' to labour/work/make

So a more precise translation would be...

7 Forming [rc,yE] light, and carving [ar"B'] out darkness, making [hf'[] peace, and carving out [ar"B] evil, I, [am] , doing/making [hf'['] all these things.' (Isaiah 45)

is carving out evil in the sense of defining it as lawlessness which is symbolised by darkness. He is making a separation between the light and the darkness, the lawful and the lawless. He forms or formulates light, which shows you which way to go and is the law of what you should do. Then he carves out darkness, which is the law of what you should not do. 

4 The Rock, perfect is his activity, For all his ways are justice. A God of faithfulness, with whom there is no injustice; Righteous and upright is he. (Deuteronomy 32 )

So God cannot do evil, he cannot himself sin, breaking a law which he has signed up to. But he can and does define evil, being a lawmaker.

5 And this is the message which we have heard from Him, and we proclaim to you: God is light, and no darkness is in Him, none! (1 John 1 )

9 out of the 10 commandments were all prohibitions, these were the law of the darkness. Then elevated two other laws to be commandments or exhortations, which are the law of the light. 

36 Teacher, which is the greatest commandment in the Law?
37 He said to him: You must love your God with your whole heart and with your whole soul and with your whole mind.
38 This is the greatest and first commandment.
39 The second, like it, is this: You must love your neighbour as yourself.
40 On these two commandments the whole Law hangs, and the Prophets (Matthew 22).

These are both proactive exhortations. Whereas the 10 commandments say...

1 And God proceeded to speak all these words, saying: 
2 I am your God, who have brought you out of the land of Egypt, out of the house of slaves. [1]
3 You must not have any other gods against my face. [1] 
4 You must not make for yourself a carved image or a form like anything that is in the heavens above or that is on the earth underneath or that is in the waters under the earth. [2]
5 You must not bow down to them nor be induced to serve them, because I your God am a God exacting exclusive devotion, bringing punishment for the error of fathers upon sons, upon the 3rd generation and upon the 4th generation, in the case of those who hate me.
6 But exercising loving-kindness toward the thousandth generation in the case of those who love me and keep my commandments [2].
7 You must not take up the name of your God in a worthless way, for will not leave the one unpunished who takes up his name in a worthless way [3].
8 Remembering the Sabbath day to hold it sacred, [4]
9 you are to render service and you must do all your work 6 days. [4]
10 But the 7th day is a Sabbath to your God. You must not do any work, you nor your son nor your daughter, your slave man nor your slave girl nor your domestic animal nor your alien resident who is inside your gates. [4]
11 For in 6 days made the heavens and the earth, the sea and everything that is in them, and he proceeded to rest on the 7th day. That is why blessed the Sabbath day and proceeded to make it sacred. [4]
12 Honor your father and your mother in order that your days may prove long upon the ground that your God is giving you. [5]
13 You must not murder. [6]
14 You must not commit adultery. [7]
15 You must not steal. [8]
16 You must not testify falsely as a witness against your fellowman. [9]
17 You must not desire your fellowman's house. You must not desire your fellowman's wife, nor his slave man nor his slave girl nor his bull nor his ass nor anything that belongs to your fellowman [10] (Exodus 20).

Only the 5th commandment to honour your parents carries a promise with it. This is because it is an exhortation to walk in the light rather than a prohibition from walking in the darkness.

So crudely speaking. told us what we should do and Moses told us what we shouldn't do.

Those who walk in the light find peace. Those who walk in the darkness do evil. For peace and evil and the consequences of light and dark behaviour.

19 Now this is the basis for judgment, that the light has come into the world but men have loved the darkness rather than the light, for their works were wicked.
20 For he that practices vile things hates the light and does not come to the light, in order that his works may not be reproved.
21 But he that does what is true comes to the light, in order that his works may be made manifest as having been worked in harmony with God. (John 3 )

The noun peace ~Alv'  is from the root ~l;v an adjective meaning. whole, entire (Gesenius)