I started playing with spec because of the idea of automated test generation, but the reality of it is that I use it as a super-charged validation library.

I think this emphasis actually does the library a disservice in that I see new users ask questions along the lines of "Should I use s/valid? to manually check inputs to my API"? The answer to that, in my usage, is "Yes! Of course!", but many people seem to think that they are using Spec wrong if they use it for something other than instrumentation and generation.

When writing complicated macros, Spec conforming is so useful!

Edit: oh I understand what you mean, you were thinking of skipping the s/conform part, and use core.match directly. Personally, I consider spec an excellent library to describe the shape of data, and core.match allows for better describing the actions you want to take based upon that.

For example, with spec you can define a bunch of alternatives using s/or, and then use core.match to then easily traverse the results.

It’s more a matter of separation of concerns to me. I don’t use core.match for validation or describing shapes of data.

Let's say I have something like

  (s/def :thespec (s/or :foo ::foo 
                        :bar ::bar))

  (match [(s/conform :thespec val)]
    [:foo x] (do-something-with x)
    [:bar y] (do-something-else-with y))

so that "john mcallister" yields { :name "john" :lastname "mcallister" } but "john " would yield { :name "john" :lastname nil } (or :todo even)

/me goes to prolog