removing Some and Nothing iterate methods and adding astuple method

base/experimental.jl

@@ -359,4 +359,47 @@ adding them to the global method table.
 """
 :@MethodTable
 
+"""
+    astuple(x::Union{X, Nothing})
+
+Converts values so that `nothing` becomes `()` and any other values are wrapped into a singleton tuple.
+
+# Example
+
+```
+julia> data = match.(r"(x.?)", ["x", "aoeu", "xoxo", ">>=", ";qjkx"])
+5-element Vector{Union{Nothing, RegexMatch}}:
+ RegexMatch("x", 1="x")
+ nothing
+ RegexMatch("xo", 1="xo")
+ nothing
+ RegexMatch("x", 1="x")
+
+julia> filter(!isnothing, data)
+3-element Vector{Union{Nothing, RegexMatch}}:
+ RegexMatch("x", 1="x")
+ RegexMatch("xo", 1="xo")
+ RegexMatch("x", 1="x")
+
+julia> collect(Iterators.flatten(astuple.(data)))
+3-element Vector{RegexMatch}:
+ RegexMatch("x", 1="x")
+ RegexMatch("xo", 1="xo")
+ RegexMatch("x", 1="x")
+
+julia> [optx for optx in data if !isnothing(optx) && optx[1] != "x"]
+1-element Vector{RegexMatch}:
+ RegexMatch("xo", 1="xo")
+
+julia> Iterators.flatmap(astuple.(data)) do optx
+           Iterators.flatmap(optx) do x
+               x[1] == "x" ? () : (x,)
+           end
+       end |> collect
+1-element Vector{RegexMatch}:
+ RegexMatch("xo", 1="xo")
+```
+"""
+astuple(x::Union{X, Nothing}) where {X} = isnothing(x) ? () : (x,)
+
 end

base/iterators.jl

@@ -1209,9 +1209,6 @@ julia> flatmap(1:3) do j
 # flatmap = flatten ∘ map
 flatmap(f, c...) = flatten(map(f, c...))
 
-# Allows filtering through `flatten` (or `flatmap`) by removing `nothing` values
-iterate(_::Nothing) = nothing
-
 """
     partition(collection, n)
 

base/some.jl

@@ -143,8 +143,3 @@ macro something(args...)
     something = GlobalRef(Base, :something)
     return :($something($expr))
 end
-
-# Allows filtering through `flatten` (or `flatmap`) by retaining `Some` values
-iterate(x::Some{T}) where T = (something(x), nothing)
-iterate(x::Some{T}, state::Nothing) where T = nothing
-length(x::Some{T}) where T = 1

test/iterators.jl

@@ -469,8 +469,7 @@ end
 @test length(flatten(1:6)) == 6
 @test collect(flatten(Any[])) == Any[]
 @test collect(flatten(())) == Union{}[]
-@test collect(flatten([Some(1)])) == [1]
-@test collect(flatten([nothing])) == Any[]
+@test collect(flatten(astuple.([1,nothing]))) == [1]
 @test_throws ArgumentError length(flatten(NTuple[(1,), ()])) # #16680
 @test_throws ArgumentError length(flatten([[1], [1]]))
 
@@ -480,11 +479,9 @@ end
 
 # flatmap
 # -------
-@test flatmap(1:3) do j
-           flatmap(1:3) do k
-               j>k ? Some((j,k)) : nothing
-           end
-       end |> collect == [(j,k) for j in 1:3 for k in 1:3 if j>k]
+@test flatmap(1:3) do j flatmap(1:3) do k
+    j!=k ? ((j,k),) : ()
+end end |> collect == [(j,k) for j in 1:3 for k in 1:3 if j!=k]
 
 # partition(c, n)
 let v = collect(partition([1,2,3,4,5], 1))