Why is that```d = Dict("a"=>1, "b"=>2, "c"=>3)filter!(d) do (k, v)

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1

Why is that

d = Dict("a"=>1, "b"=>2, "c"=>3)
filter!(d) do (k, v)
    iseven(v)
end

is happy, but

d = Dict("a"=>1, "b"=>2, "c"=>3)
filter!((k,v) -> iseven(v), d)

is sad and throws ERROR: MethodError: no method matching (::var"#114#115")(::Pair{String,Int64})? How am I doing this wrong?

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Quoting the answer from Frederik Ekre below:

You need filter(((k,v),) -> iseven(v), d)

And more in-depth Q/A replies:

Q: I had tried ((k,v)) but I didn’t realize I needed to turn it into a tuple.
A: ((k,v)) is just (k,v) just like (1) is just 1 .
A: filter gives you a single pair that you need to destruct, so you need to create a function that takes a single argument
Q: But why don’t I run into this with the do form?
A: do (k, v) is a single argument function while do k, v is a two argument function

EDIT: This issue is relevant destructuring inconsistency with anonymous functions · Issue #36595 · JuliaLang/julia · GitHub

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