请问x -> ForwardDiff_res(x, user_ctx)里->符号是什么意思

我在读PETSc.jl里DMSTAG_Stokes_2D.jl这个例子时,遇到这样一段代码:

function ComputeSparsityPatternJacobian_automatic(x_l, user_ctx)
# This computes the sparsity pattern and coloring of the jacobian automatically
# This will works for any equation but is slow @ high resolutions

f_Residual  =   (x -> ForwardDiff_res(x, user_ctx));        # pass additional arguments into the routine
J_julia     =   ForwardDiff.jacobian(f_Residual,x_l*0 .+ 1);# Compute a "blank" jacobian  

# employ sparse structure to compute jacobian - to be moved inside routines
jac         =   sparse(J_julia);
colors      =   matrix_colors(jac)          # the number of nonzeros per row

return jac, colors

end

想问里面的x → ForwardDiff_res(x, user_ctx)是什么意思?或者在manual哪里可以找到相关内容。第一次遇到这种写法,不是很理解,manual里也没找到相关内容。

匿名函数,有问题先看手册跟 help

help?> ->
search: ->

  x -> y

  Create an anonymous function mapping argument(s) x to the function body y.

  julia> f = x -> x^2 + 2x - 1
  #1 (generic function with 1 method)
  
  julia> f(2)
  7

  Anonymous functions can also be defined for multiple argumets.

  julia> g = (x,y) -> x^2 + y^2
  #2 (generic function with 1 method)
  
  julia> g(2,3)
  13

  See the manual section on anonymous functions for more details.