Unhelpful output `#27 (generic function with 1 method)` about fileio.jl

[ararslan]

This is because the save(path) method is "curried," i.e. it returns a function that accepts an object as input and calls save(path, object). What you see printed in the REPL is due to how Julia names anonymous functions (see the second paragraph of the relevant manual section). That is to say, what you're observing is expected behavior, though it is apparently not actually documented anywhere except in a comment near the line in the code you linked that save behaves this way.

(I'll note as an aside that I'm personally of the opinion that packages shouldn't provide curried methods and it should be up to the user to obtain whatever unclear syntax they want via macros from separate packages. This is admittedly a rather spicy take that I'm sure almost no one agrees with, but it would at least improve the situation you're observing.)

Removing the aforementioned curried method would be a breaking change, so one possible solution here would be to improve the docstring for save by including something along the lines of

"""
    save(file; kwargs...) -> Function

Return an anonymous function that accepts a single argument `x` as
input and returns `save(file, x; kwargs...)`. Note that `x` should
be savable in the given file type; consult the relevant package
documentation for more information.
"""

[ararslan]

Actually, there is an existing issue #324 which discusses this case and removing the curried method was already proposed in that thread. 😄 I'll close this issue and further discussion and can be directed to that thread.