They are both engine templates, and they have different functionality.
There will never be any converter, because there are so few cases when such a tool is needed. Such a tool should support both language functions, but they are not fully compatible (there are things that exist in one and are not available in the other, and vice versa).
To answer your original question, how can you convert slim to erb, I answer that you need to learn both languages ββand do it manually.
My suggestion is that you study the one you plan to use and stick to (My suggestion is ERB). If you are a beginner, do not jump on different engines, stick to one, study it to the bone, and then, after many years of experience, try to do the same or do better with other engines.
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