Fix broadcast() and map() with constructors

src/broadcast.jl

@@ -1,4 +1,3 @@
-using Base: _default_eltype
 using Compat
 
 if VERSION >= v"0.6.0-dev.693"
@@ -10,6 +9,8 @@ else
 end
 
 if VERSION < v"0.6.0-dev" # Old approach needed for inference to work
+    using Base: _default_eltype
+
     ftype(f, A) = typeof(f)
     ftype(f, A...) = typeof(a -> f(a...))
     ftype(T::DataType, A) = Type{T}
@@ -20,12 +21,12 @@ if VERSION < v"0.6.0-dev" # Old approach needed for inference to work
     else
         using Base: Zip2
     end
-    ziptype(A) = Tuple{eltype(A)}
-    ziptype(A, B) = Zip2{Tuple{eltype(A)}, Tuple{eltype(B)}}
+    ziptype(A) = Tuple{eltype(eltype(A))}
+    ziptype(A, B) = Zip2{Tuple{eltype(eltype(A))}, Tuple{eltype(eltype(B))}}
     @inline ziptype(A, B, C, D...) = Zip{Tuple{eltype(A)}, ziptype(B, C, D...)}
 
     nullable_broadcast_eltype(f, As...) =
-        eltype(_default_eltype(Base.Generator{ziptype(As...), ftype(f, As...)}))
+        _default_eltype(Base.Generator{ziptype(As...), ftype(f, As...)})
 else
     Base.@pure nullable_eltypestuple(a) = Tuple{eltype(eltype(a))}
     Base.@pure nullable_eltypestuple(T::Type) = Tuple{Type{eltype(T)}}

src/lift.jl

@@ -7,7 +7,7 @@ eltypes(x) = Tuple{eltype_nullable(x)}
 eltypes(x, xs...) = Tuple{eltype_nullable(x), eltypes(xs...).parameters...}
 
 """
-  lift(f, xs...)
+    lift(f, xs...)
 
 Lift function `f`, passing it arguments `xs...`, using standard lifting semantics:
 for a function call `f(xs...)`, return null if any `x` in `xs` is null; otherwise,
@@ -17,13 +17,13 @@ return `f` applied to values of `xs`.
     N = nfields(xs)
     args = (:(unsafe_get(xs[$i])) for i in 1:N)
     checknull = (:(!isnull(xs[$i])) for i in 1:N)
-    if null_safe_op(f.instance, map(eltype_nullable, xs.parameters)...)
+    if isdefined(f, :instance) && null_safe_op(f.instance, map(eltype_nullable, xs.parameters)...)
         return quote
             val = f($(args...))
             nonull = (&)($(checknull...))
             @compat Nullable(val, nonull)
         end
-    else
+    elseif VERSION >= v"0.6.0-dev"
       return quote
           U = Core.Inference.return_type(f, eltypes(xs...))
           if (&)($(checknull...))
@@ -32,6 +32,22 @@ return `f` applied to values of `xs`.
               return isleaftype(U) ? Nullable{U}() : Nullable()
           end
       end
+    else # Inference fails with the previous branch on Julia 0.5
+      if isdefined(f, :instance)
+          U = Core.Inference.return_type(f.instance, map(eltype_nullable, xs.parameters))
+          isleaftype(U) || (U = Union{})
+      elseif F === DataType # Function is a constructor
+          U = f.parameters[1]
+      else
+          U = Union{}
+      end
+      return quote
+          if (&)($(checknull...))
+              return Nullable(f($(args...)))
+          else
+              return Nullable{$U}()
+          end
+      end
     end
 end
 

test/broadcast.jl

@@ -36,6 +36,10 @@ module TestBroadcast
     f(x::Real, y::Real) = x * y
     f(x::Real, y::Real, z::Real) = x * y * z
 
+    @inferred NullableArrays.lift(f, (1,))
+    @inferred NullableArrays.lift(f, (1, 2.0))
+    @inferred NullableArrays.lift(f, (1, 2.0, 3.0))
+
     for (dests, arrays, nullablearrays, mask) in
         ( ((C2, Z2), (A1, A2), (U1, U2), ()),
           ((C3, Z3), (A2, A3), (U2, U3), ()),
@@ -106,4 +110,15 @@ module TestBroadcast
     @test isequal(broadcast(&, X, Y), NullableArray(A .& B, M1 .| M2))
     @test isequal(broadcast(|, X, Y), NullableArray(A .| B, M1 .| M2))
 
+    # Test broadcasting with constructor
+    immutable SurvEvent
+        time::Float64
+        censored::Bool
+    end
+    t = NullableArray(rand(3))
+    c = NullableArray(rand(Bool, 3))
+    @test isequal(SurvEvent.(t, c), NullableArray([SurvEvent(get(t[i]), get(c[i])) for i in 1:3]))
+    @test isa(SurvEvent.(t, c), NullableVector{SurvEvent})
+    @inferred NullableArrays.lift(SurvEvent, (1, true))
+
 end # module