如何使用 splat 运算符注释类型

Question

如何（是否可能）在使用 splat 运算符时注释参数类型？

f(x, y) = x^2 + y^2
vec = [1.0, 2.0, 'a']
f(vec[1:2]...)

如何在函数调用中注释 ... 的使用。还要注意 none 的宏来查看代码 (@code_llvm, @code_lowered, @code_native, @code_typed, @code_warntype) 工作，所以它会使用 splat 时很难优化吗？

Answer 1

因为在上面的用例中，反射函数的宏版本似乎无法达到正确的参数类型，使用原始函数而不是宏，可能会有帮助：

f(x, y) = x^2 + y^2
vec = [1.0, 2.0, 'a']
@code_warntype(f(vec[1:2]...)) # => Nothing
code_warntype(f,map(typeof,vec[1:2])) 
#  Variables:
#  x::Float64
#  y::Float64
#  .....

这个逻辑适用于所有反射宏，使用它们的变体函数和 (function, collection of types)。

参考文献：

宏@code_warntype 具有函数变体：@code_warntype
宏的生成方式：macro generator
Util 函数达到类型：gen_call_with_extracted_types

Answer 2

我想你的意思是这样的：

julia> foo(args::Float64...) = sum([x^2 for x in args])::Float64
foo (generic function with 1 method)

julia> foo(args::Vector{Float64}) = foo(args...)::Float64
foo (generic function with 2 methods)

julia> foo(args::Tuple{Vararg{Float64}}) = foo(args...)::Float64
foo (generic function with 3 methods)

julia> foo(2.0, 5.5, 7.0)
83.25

julia> v = Float64[2, 5.5, 7.0]
    3-element Array{Float64,1}:
     2.0
     5.5
     7.0

julia> foo(v)
83.25

julia> t = tuple(v...)
(2.0,5.5,7.0)

julia> foo(t)
83.25

我在几个地方放置了类型注释，因此您可以了解各种可能性。

julia> @which foo(2.0, 5.5, 7.0)
foo(args::Float64...) at none:1

julia> @which foo(v)
foo(args::Array{Float64,1}) at none:1

julia> @which foo(t)
foo(args::Tuple{Vararg{Float64}}) at none:1

@code_warntype等

julia> @code_warntype foo(2.0, 5.5, 7.0)
Variables:
  args::Tuple{Float64,Float64,Float64}
  #s33::Int64
  #s32::Int64
  #s31::Int64
  x::Float64
  #s30::Int64

Body:
  begin  # none, line 1:
      GenSym(1) = (Base.nfields)(args::Tuple{Float64,Float64,Float64})::Int64
      0:
      GenSym(3) = (top(ccall))(:jl_alloc_array_1d,(top(apply_type))(Base.Array,Float64,1)::Type{Array{Float64,1}},(top(svec))(Base.Any,Base.Int)::SimpleVector,Array{Flo
at64,1},0,GenSym(1),0)::Array{Float64,1}
      #s33 = 1
      #s32 = 1
      #s31 = 0
      unless (Base.box)(Base.Bool,(Base.not_int)(#s31::Int64 === GenSym(1)::Bool)::Any)::Bool goto 2
      3:
      #s31 = (Base.box)(Base.Int,(Base.add_int)(#s31::Int64,1)::Any)::Int64
      GenSym(10) = (Base.getfield)(args::Tuple{Float64,Float64,Float64},#s32::Int64)::Float64
      GenSym(11) = (Base.box)(Base.Int,(Base.add_int)(#s32::Int64,1)::Any)::Int64
      #s30 = 1
      GenSym(12) = GenSym(10)
      GenSym(13) = (Base.box)(Base.Int,(Base.add_int)(1,1)::Any)::Int64
      x = GenSym(12)
      #s30 = GenSym(13)
      GenSym(14) = GenSym(11)
      GenSym(15) = (Base.box)(Base.Int,(Base.add_int)(2,1)::Any)::Int64
      #s32 = GenSym(14)
      #s30 = GenSym(15)
      GenSym(4) = (Base.box)(Base.Float64,(Base.mul_float)(x::Float64,x::Float64)::Any)::Float64
      $(Expr(:type_goto, 0, GenSym(4)))
      $(Expr(:boundscheck, false))
      (Base.arrayset)(GenSym(3),GenSym(4),#s33::Int64)::Array{Float64,1}
      $(Expr(:boundscheck, :(Main.pop)))
      #s33 = (Base.box)(Base.Int,(Base.add_int)(#s33::Int64,1)::Any)::Int64
      4:
      unless (Base.box)(Base.Bool,(Base.not_int)((Base.box)(Base.Bool,(Base.not_int)(#s31::Int64 === GenSym(1)::Bool)::Any)::Bool)::Any)::Bool goto 3
      2:
      1:
      GenSym(8) = GenSym(3)
      return (Base._mapreduce)($(Expr(:new, :((top(getfield))(Base,:IdFun)::Type{Base.IdFun}))),$(Expr(:new, :((top(getfield))(Base,:AddFun)::Type{Base.AddFun}))),GenSy
m(8))::Float64
  end::Float64

julia> @code_warntype foo(v)
Variables:
  args::Array{Float64,1}

Body:
  begin  # none, line 1:
      return (top(_apply))((top(getfield))(Main,:call)::F,Main.foo,args::Array{Float64,1})::Float64
  end::Float64

julia> @code_warntype foo(t)
Variables:
  args::Tuple{Float64,Float64,Float64}

Body:
  begin  # none, line 1:
      return (Main.foo)((top(getfield))(args::Tuple{Float64,Float64,Float64},1)::Float64,(top(getfield))(args::Tuple{Float64,Float64,Float64},2)::Float64,(top(getfield))(args::Tuple{Float64,Float64,Float64},3)::Float64)::Float64
  end::Float64

编辑： IJulia 笔记本，测试于 juliabox.org，Julia v0.4.1：

http://nbviewer.ipython.org/gist/Ismael-VC/edeb2f919c2341cb389c

你也可以在调用函数的时候加上类型注解：

julia> @which foo(t::Tuple{Vararg{Float64}}...)
foo(args::Tuple{Vararg{Float64}}) at none:1

julia> @which foo(v::Vector{Float64}...)
foo(args::Array{Float64,1}) at none:1

如何使用 splat 运算符注释类型

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