Correctly generate function from user input

[ry-dgel]

I’ve already read through the following threads, and while giving solid advice, I feel that they don’t entirely apply to my situation, and have yet to tease out a working solution from the information they provide…

Julia: invoke a function by a given string

How do I create a function from an expression

Suppose I have expr = :(sin(x)+cos(x)) How can I get a function looking like x->sin(x)+cos(x) I have tried to write such a macro macro expr2fn(expr, arg) return :($arg -> $(expr)) end but it does not work julia> f = @expr2fn expr x (::#63) (generic function with 1 method) julia> f(1.0) :(sin(x) + cos(x)) Not sure what is happening here.

Parsed anonymous functions, type inference, and Base.invokelatest

I have a situation where at some point during runtime a string is parsed and eval’d to an anonymous function, e.g. fa = eval(parse("x -> mean(x)")) Using Julia v0.5, I could then call fa([1,2,3]) later in the same routine without a problem. In v0.6 however, such a call results in a MethodError mentioning the “world age”. Reading the docs suggests using: Base.invokelatest(fa, [1,2,3]) which works, but, according to the docstrings for invokelatest the type of the output from from the call to f…