Matching Expr

[magistere]

Is it possible to match Expr expressions? The following script gives error ERROR: args not defined

using Match

function get_args(ex::Expr)
    @match ex begin
        Expr(:call, {:+, args}, _) => args
        _ => "None"
    end
end

println(get_args(:(x+1)))
println(get_args(Expr(:call, :+, :x, 1)))

[kmsquire]

It's intended to work, since Exprs are just types, but I hadn't tested it. I'll take a look.

[kmsquire]

Thanks for the report. I just pushed a fix. Update and let me know if it works (or not) for you, or if you find any other issues.

Note that for this to work, you'll need to add ellipses to the args variable inside of the call:

    @match ex begin
        Expr(:call, {:+, args...}, _) => args
        _ => "None"
    end

Cheers, Kevin

[magistere]

Kevin, thank you for quick fix and updating the package in repository. It works great now. When I read package documentation on array matching, I've found one discrepancy in chapter "Extract first element, rest of vector". Now type of b is SubArray, not Array.

julia> @match([1:4], [a,b...])
(1,[2,3,4])

julia> a
1

julia> b
3-element SubArray{Int32,1,Array{Int32,1},(Range1{Int32},)}:
 2
 3
 4

I'd like to correct this myself, but I assume documentation sources are not on the GitHub.

[kmsquire]

Glad to hear it! The documentation sources are in the doc directory.

[kmsquire]

And yes, the change from Array to SubArray was made a little while back, and I forgot to change the documentation. Now that you brought it to my attention, I'll get to it eventually, but a pull request would be quite welcome.

[magistere]

Done #5