filter(f, ::NamedTuple) (#839)

Author: mtfishman

Project.toml

@@ -1,6 +1,6 @@
 name = "Compat"
 uuid = "34da2185-b29b-5c13-b0c7-acf172513d20"
-version = "4.16.0"
+version = "4.17.0"
 
 [deps]
 Dates = "ade2ca70-3891-5945-98fb-dc099432e06a"

README.md

@@ -72,6 +72,8 @@ changes in `julia`.
 
 ## Supported features
 
+* `filter` can now act on a `NamedTuple` [#50795]. (since Compat 4.17.0)
+
 * `insertdims(D; dims)` is the opposite of `dropdims` ([#45793]) (since Compat 4.16.0)
 
 * `Compat.Fix{N}` which fixes an argument at the `N`th position ([#54653]) (since Compat 4.16.0)
@@ -197,4 +199,5 @@ Note that you should specify the correct minimum version for `Compat` in the
 [#47679]: https://github.com/JuliaLang/julia/pull/47679
 [#48038]: https://github.com/JuliaLang/julia/issues/48038
 [#50105]: https://github.com/JuliaLang/julia/issues/50105
+[#50795]: https://github.com/JuliaLang/julia/issues/50795
 [#54653]: https://github.com/JuliaLang/julia/issues/54653

src/Compat.jl

@@ -797,6 +797,14 @@ if VERSION < v"1.11.0-DEV.1562"
     end
 end
 
+# https://github.com/JuliaLang/julia/pull/50795
+if VERSION < v"1.11.0-DEV.1457"
+    Base.filter(f, xs::NamedTuple) = _getindex(xs, filter(k -> f(xs[k]), keys(xs)))
+    # `getindex(::NamedTuple, ::Tuple{Vararg{Symbol}})` is not defined in Julia 1.6.
+    # Introduced in https://github.com/JuliaLang/julia/pull/38878.
+    @inline _getindex(t::NamedTuple, idxs::Tuple{Vararg{Symbol}}) = NamedTuple{idxs}(t)
+end
+
 # https://github.com/JuliaLang/julia/pull/45052
 if VERSION < v"1.9.0-DEV.461"
     Base.VersionNumber(v::VersionNumber) = v

test/runtests.jl

@@ -1071,3 +1071,12 @@ end
         end
     end
 end
+
+# https://github.com/JuliaLang/julia/pull/50795
+@testset "filter on NamedTuple" begin
+    @test filter(isodd, (a=1,b=2,c=3)) === (a=1, c=3)
+    @test filter(i -> true, (;)) === (;)
+    longnt = NamedTuple{ntuple(i -> Symbol(:a, i), 20)}(ntuple(identity, 20))
+    @test filter(iseven, longnt) === NamedTuple{ntuple(i -> Symbol(:a, 2i), 10)}(ntuple(i -> 2i, 10))
+    @test filter(x -> x<2, (longnt..., z=1.5)) === (a1=1, z=1.5)
+end