Slowly but steadily, I’m now ready to continue reading [WayBack] From design patterns to category theory.
I found it two years ago after stumbling into [WayBack] Semigroups accumulate and [WayBack] Monoids accumulate. Both articles indicate they are part of two distinct series: [WayBack] Semigroups and [WayBack] Monoids which both in turn indicate the same super-series: [WayBack] Monoids, semigroups, and friends.
That intrigued me, as from a casual interest in Semigroups I got into a really structured coverage of many related topics leading all the way to design patterns. How cool is that!
Back than, I lacked some of the vocabulary I needed to fully grasp this, as part of the posts use the functional programming perspective which – for geeks like me that grew up in the procedural, object-oriented, and interface-polymorphism eras – takes some time to wrap their head around.
I did learn a thing or two back then, for instance the series taught me that some semigroups are not monoids. The diagram on the right shows how the various groups are related. But I could not replicate that knowledge, clearly lacking the words to explain it to myself.
What I really liked is the humble way in which the author – Mark Seeman – indicated that when he first thought about these topics himself, he too had still a lot of things to learn, including acquiring the vocabulary:
My first attempt at answering these questions was in 2010, but while I had the experience that certain abstractions composed better than others, I lacked the vocabulary. I’ve been wanting to write a better treatment of the topic ever since, but I’ve been constantly learning as I’ve grappled with the concepts.
Like me, he is on a life long quest in learning new things every day.
Now that I’ve done more functional programming (mainly from object-oriented code bases), I think I’m more equipped to digest his writings, better understand them and maybe even explain them.
By now there also should be more topics than these ones:
- [WayBack] Monoids, semigroups, and friends
- [WayBack] Monoids
- [WayBack] Semigroups
- Quasigroups
- Magmas
- Rock Paper Scissors magma
- Colour-mixing magma
- Software design isomorphisms
- Unit isomorphisms
- Function isomorphisms
- Argument list isomorphisms
- Uncurry isomorphisms
- Object isomorphisms
- Abstract class isomorphism
- Inheritance-composition isomorphism
- From structural patterns to category theory
- Composite as a monoid
- Coalescing Composite as a monoid
- Endomorphic Composite as a monoid
- Null Object as identity
Time to do some reading over the next weeks…
–jeroen
The Wiert Corner - irregular stream of stuff 