The tutorial shows some very basic examples of pattern matching, such as matching over an integer to emulate a c-style switch statement. The tutorial also shows how to do basic destructuring over a tuple type, and destructuring structures.
It seems like it should be possible to pattern match over a vector but I cannot figure out the right syntax for it and I haven't found any examples of it.
For example, in Haskell you can easily destructure a list:
foldr :: (a -> b -> b) -> b -> [a] -> b
foldr func initValue [] = initValue
foldr func initValue (x:xs) = func initValue $ foldr initValue func xs
So, looking at a rough translation, it would be nice to be able to do:
fn foldr<A, B>(func: fn(A, B) -> B,
initValue: B,
vals: [A]) -> B {
alt vals {
[] { ret initValue; }
_ {
let h = vec::head(vals),
t = vec::tail(vals);
ret foldr(func, func(initValue, h), t);
}
}
}
Note: I know you could use an if statement here, I am just using this as an example of pattern matching over a vector.
This currently returns:
patterns.rs:10:4: 10:5 error: constant contains unimplemented expression type
patterns.rs:10 [] { ret initValue; }
^
error: aborting due to previous errors
There is an example in the tutorial for destructuring structures (defined with { .. }
) and tuples (defined with ( .. )
), so it seems like there should be built-in support for vectors as well considering they also contain a special syntax (defined with [ .. ]
).
Feel free to correct me if I am using vectors in the wrong way as well.
be
as a keyword but they don't make an references to it at the moment – Macfarlane