match
A minimal pattern matching library for zepto.
Installation
zeps install zepto-lang/match
# if you want to test your version of match
zeps test match
Usage
For the normal user, there is but one endpoint
named match. Let's see how fizzbuzz is defined in terms
of this:
(define (fizzbuzz n)
(do ((i 1 (add1 i))) ((> i n))
(match (list (modulo i 5) (modulo i 3))
(((0 0) (write "fizzbuzz"))
((_ 0) (write "fizz"))
((0 _) (write "buzz"))
((_ _) (write i))))))
(fizzbuzz 15) ; => will print fizzbuzz until 15 inclusively
```
What does this do? Well, it counts from 1 to n (including n),
and doing a match function on the two needed moduli. If both are 0,
`fizzbuzz` is printed. If the second one (mod 3) is 0, `fizz` is printed...
You get the idea.
Deeply nested structures can also be matched, of course.
## Caveats
The pattern matching is *really* basic (the whole module amounts
to 34 lines). Some of the weaknesses are:
- Nesting and taking doesn't really play well with data structures other than lists.
While (byte)vectors also work within structures, they currently do not work on the top level.
- There are no regexes, simply because zepto does not have regexes *yet*.
- There is no "catch-all" clause.
I hope this does not put you off too much. It should be somewhat
interesting to use anyway.
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Have fun!