print NamedTuple types using the macro format

Author: KristofferC

base/show.jl

@@ -1060,11 +1060,12 @@ end
 function show_datatype(io::IO, x::DataType, wheres::Vector{TypeVar}=TypeVar[])
     parameters = x.parameters::SimpleVector
     istuple = x.name === Tuple.name
+    isnamedtuple = x.name === typename(NamedTuple)
     n = length(parameters)
 
     # Print tuple types with homogeneous tails longer than max_n compactly using `NTuple` or `Vararg`
-    max_n = 3
     if istuple
+        max_n = 3
         taillen = 1
         for i in (n-1):-1:1
             if parameters[i] === parameters[n]
@@ -1090,6 +1091,20 @@ function show_datatype(io::IO, x::DataType, wheres::Vector{TypeVar}=TypeVar[])
             end
             print(io, "}")
         end
+    elseif isnamedtuple
+        print(io, "@NamedTuple{")
+        syms, types = parameters
+        first = true
+        for i in 1:length(syms)
+            if !first
+                print(io, ", ")
+            end
+            print(io, syms[i])
+            print(io, "::")
+            show(io, types.parameters[i])
+            first = false
+        end
+        print(io, "}")
     else
         show_type_name(io, x.name)
         show_typeparams(io, parameters, (unwrap_unionall(x.name.wrapper)::DataType).parameters, wheres)

test/show.jl

@@ -1348,6 +1348,12 @@ test_repr("(:).a")
 @test repr(Tuple{String, Int64, Int64, Int64}) == "Tuple{String, Int64, Int64, Int64}"
 @test repr(Tuple{String, Int64, Int64, Int64, Int64}) == "Tuple{String, Vararg{Int64, 4}}"
 
+# Test printing of NamedTuples using the macro syntax
+@test repr(@NamedTuple{kw::Int64}) == "@NamedTuple{kw::Int64}"
+@test repr(@NamedTuple{kw::Union{Float64, Int64}, kw2::Int64}) == "@NamedTuple{kw::Union{Float64, Int64}, kw2::Int64}"
+@test repr(@NamedTuple{kw::@NamedTuple{kw2::Int64}}) == "@NamedTuple{kw::@NamedTuple{kw2::Int64}}"
+@test repr(@NamedTuple{kw::NTuple{7, Int64}}) == "@NamedTuple{kw::NTuple{7, Int64}}"
+
 @testset "issue #42931" begin
     @test repr(NTuple{4, :A}) == "NTuple{4, :A}"
     @test repr(NTuple{3, :A}) == "Tuple{:A, :A, :A}"