Generally, I need only loopers. A looper generates a series of signal in sequence.
Say, I need to make an intersection connecting 3 directions with traffic light. I need a looper to give out 0 for 30 sec and 1 for 30s and 2 for 30s to controller the lights. I could do it with the circuit system in vanilla game. But very many people find it difficult to do this. They have to learn for 1 or 2 hours to get hang of that trick.
And in other cases, I let belt work for 9/134 of all time, which gives a lane the perfect coal it needs to smelt all the ore filling in that lane of belts.
That's all. Thanks.

The idea of this mod is to provide generic circuits, not specific circuits, the integrated systems follow instructions, thoses instructions permit to get and set any cell in connected programmable components, wait a number of ticks and go to any instructions including start of program, so in a way it already permit to do loops, simply not in the easiest way.

Thanks for replying. I think I should say, then the suggestion should get modified a little bit. Here's the new idea.
Some new entity, which acts absolutely the same as the one you already developed. The recipe for new entity is 1xalready developed -> 1xnew entity. Rather than a crafting, it's more likely a transform. The new entity code as a loop by default. Players are still able to modify its scripts manually.
Means, it only provides a default template for specified purpose. Which helps people learn to use your mod in game. I think it's very important for your mod to spread.

For that I had developped an idea which use informatron, basically the mod provide through informatron a documentation, example with blueprints and finally blueprint and code templates which serve specific general purpose, also with the idea of the mod DISK, I would provide the code templates as DISK that can be loaded in computers (the disk reader and writer would contain preprogrammed function that would write the disk to memory or write memory to disk)

This game is somehow lack of standard entities for specific purpose, which force people to prepare tons of blueprints and spend time learning structures and building very complicated combinations over and over again. You are definitely doing something helpful and meaningful.
Good luck.