map on pairs on NamedTuples doesn't work

[quinnj]

julia> t = (a=1, b=2, c=3)
(a = 1, b = 2, c = 3)

julia> map(println, pairs(t))
ERROR: MethodError: Cannot `convert` an object of type Base.Generator{Base.Iterators.IndexValue{Symbol,Int64,Tuple{Symbol,Symbol,Symbol},NamedTuple{(:a, :b, :c),Tuple{Int64,Int64,Int64}}},typeof(println)} to an object of type Base.Iterators.IndexValue{Symbol,Int64,Tuple{Symbol,Symbol,Symbol},NamedTuple{(:a, :b, :c),Tuple{Int64,Int64,Int64}}}
This may have arisen from a call to the constructor Base.Iterators.IndexValue{Symbol,Int64,Tuple{Symbol,Symbol,Symbol},NamedTuple{(:a, :b, :c),Tuple{Int64,Int64,Int64}}}(...),
since type constructors fall back to convert methods.
Stacktrace:
 [1] Base.Iterators.IndexValue{Symbol,Int64,Tuple{Symbol,Symbol,Symbol},NamedTuple{(:a, :b, :c),Tuple{Int64,Int64,Int64}}}(::Base.Generator{Base.Iterators.IndexValue{Symbol,Int64,Tuple{Symbol,Symbol,Symbol},NamedTuple{(:a, :b, :c),Tuple{Int64,Int64,Int64}}},typeof(println)}) at ./sysimg.jl:124
 [2] map(::Function, ::Base.Iterators.IndexValue{Symbol,Int64,Tuple{Symbol,Symbol,Symbol},NamedTuple{(:a, :b, :c),Tuple{Int64,Int64,Int64}}}) at ./deprecated.jl:57
 [3] top-level scope

[JeffBezanson]

IndexValue is an AbstractDict, so it's hitting a deprecated method designed for Dicts.

[vtjnash]

Maybe we should un-deprecate that method? But this wouldn't work anyways, since the OP should be using foreach (which already works for both):

julia> map(println, pairs(Dict(1=>2, 2=>3)))
W- `map(f, d::T) where T <: AbstractDict` is deprecated, use `T((f(p) for p = pairs(d)))` instead. -Warn:Core:julia_internal.h:380
|  caller = jl_call_fptr_internal at julia_internal.h:380 [inlined]
2 => 3
ERROR: MethodError: no method matching start(::Nothing)
Closest candidates are:
  start(::SimpleVector) at essentials.jl:550
  start(::Base.MethodList) at reflection.jl:672
  start(::ExponentialBackOff) at error.jl:171
  ...
Stacktrace:
 [1] Dict{Int64,Int64}(::Base.Generator{Dict{Int64,Int64},typeof(println)}) at ./dict.jl:116
 [2] map(::Function, ::Dict{Int64,Int64}) at ./deprecated.jl:57
 [3] top-level scope

[KristofferC]

This now gives an error that map is explicitly not implemented for this type.

[vtjnash]

dup #5794