Will Pirkle's books might be close to what you're looking for. He covers Z transforms (which you do ultimately need to understand to code up filters) but also p

Will Pirkle's books might be close to what you're looking for. He covers Z transforms (which you do ultimately need to understand to code up filters) but also provides implementations you can use as a starting point/to get a better idea of what to do concretely in software.