One remark (that may seem like a nitpick, but is in fact crucial) : composition doesn't say it "is a kind of", but rather "it has". It's the two most fundament

One remark (that may seem like a nitpick, but is in fact crucial) : composition doesn't say it "is a kind of", but rather "it has". It's the two most fundamental concept of any language : to be vs to have. Now it may or may not be just a philosophical difference and bring no practical consequences to a computer program, but at the minimum one can say it expresses two different concepts.