Yeah, nested regexes are one of the places people are most likely to be
tripped up.
One of those inner lists could be speced as:
(def string-list (s/* string?))
;; or as (s/coll-of string?) - not a strong preference in this particular
case but there are tradeoffs
And then the outer list is something like this:
(def outer (s/* (s/spec string-list))
where the s/spec is the key thing - that creates a new "sequential
context". Otherwise, the string-list regex ops become part of the outer
regex ops.
One difference here will be that the spec above will conform the
string-list to a vector (as all sequential things conform to a vector). The
coll-of approach would give you control over that though:
(s/conform (s/* (s/coll-of string? ())) ['("a" "b" "c") '("d" "e" "f")])
=> [("a" "b" "c") ("d" "e" "f")]
The benefit of using s/* in string-list is that if you wanted to include
string-list inside another regex you could but with coll-of, it would
always start a new collection:
(s/conform (s/cat :num integer? :strs string-list) [100 "a" "b"])
=> {:num 100, :strs ["a" "b"]}
So, tradeoffs.
On Monday, May 23, 2016 at 2:08:49 PM UTC-5, scott stackelhouse wrote:
>
> Could someone describe what a spec of a seq in a seq would look like?
> i.e. ['("a" "b" "c") '("d" "e" "f")]. I'm not quite "getting it."
>
> --Scott
>
> On Monday, May 23, 2016 at 7:12:29 AM UTC-7, Rich Hickey wrote:
>>
>> Introducing clojure.spec
>>
>> I'm happy to introduce today clojure.spec, a new core library and support
>> for data and function specifications in Clojure.
>>
>> Better communication
>>
>> Clojure is a dynamic language, and thus far we have relied on
>> documentation or external libraries to explain the use and behavior of
>> functions and libraries. But documentation is difficult to produce, is
>> frequently not maintained, cannot be automatically checked and varies
>> greatly in quality. Specs are expressive and precise. Including spec in
>> Clojure creates a lingua franca with which we can state how our programs
>> work and how to use them.
>>
>> More leverage and power
>>
>> A key advantage of specifications over documentation is the leverage they
>> provide. In particular, specs can be utilized by programs in ways that docs
>> cannot. Defining specs takes effort, and spec aims to maximize the return
>> you get from making that effort. spec gives you tools for leveraging specs
>> in documentation, validation, error reporting, destructuring,
>> instrumentation, test-data generation and generative testing.
>>
>> Improved developer experience
>>
>> Error messages from macros are a perennial challenge for new (and
>> experienced) users of Clojure. specs can be used to conform data in macros
>> instead of using a custom parser. And Clojure's macro expansion will
>> automatically use specs, when present, to explain errors to users. This
>> should result in a greatly improved experience for users when errors occur.
>>
>> More robust software
>>
>> Clojure has always been about simplifying the development of robust
>> software. In all languages, dynamic or not, tests are essential to quality
>> - too many critical properties are not captured by common type systems.
>> spec has been designed from the ground up to directly support generative
>> testing via test.check https://github.com/clojure/test.check. When you
>> use spec you get generative tests for free.
>>
>> Taken together, I think the features of spec demonstrate the ongoing
>> advantages of a powerful dynamic language like Clojure for building robust
>> software - superior expressivity, instrumentation-enhanced REPL-driven
>> development, sophisticated testing and more flexible systems. I encourage
>> you to read the spec rationale and overview
>> http://clojure.org/about/spec. Look for spec's inclusion in the next
>> alpha release of Clojure, within a day or so.
>>
>> Note that spec is still alpha, and some details are likely to change.
>> Feedback welcome.
>>
>> I hope you find spec useful and powerful!
>>
>> Rich
>>
>>
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