Tim: I like that idea. I also think Julia is getting pretty close to the point where one of those "watch me build a <something> in julia in 10 minutes" videos on would be popular on HN; those can be really informative for learning effective workflows in a new environment.
The release of v0.3 might be a good milestone for that; if I feel sufficiently productive in Julia by then I might try to throw something together. Although, I would prefer that the various discussions on docstrings/conventions were settled and implemented first, now that I think about it. Right now I'd be kind of embarrassed to let somebody see the way I've had to figure out 3rd party package usage (1: google it 2: search the online docs, if any 3: when those fail (most of the time), read through the entire source code of the package). On Thursday, May 8, 2014 1:23:30 PM UTC-4, Tim Holy wrote: > > Long ago I began a project to add exercises (with answers) to the > documentation. We needed better web infrastructure (and more/better > problems) > to make that practical, so that was abandoned. But for metaprogramming I > can > imagine that a few exercises might help it click. > > --Tim > > > On Thursday, May 08, 2014 10:11:34 AM Adam Smith wrote: > > I could see the potential for others to want to use this, so I made a > gist > > for it: > > https://gist.github.com/sunetos/0714ae73647160d76aae > > > > As an aside, I'm really not sure why I didn't understand macros better > > until Pierre's comment; I had read the metaprogramming > > docs<http://julia.readthedocs.org/en/latest/manual/metaprogramming/> > > multiple times. I'm only mentioning it now because I wanted to offer a > > suggestion for improving the docs, but now that I re-read that page, the > > docs seem quite thorough, so I'm just going to chalk it up to my being > in a > > daze or something. > > > > On Thursday, May 8, 2014 12:47:03 PM UTC-4, Adam Smith wrote: > > > Thanks to all for the responses! Pierre, you have made me positively > > > giddy. Your response was enough to make Julia's metaprogramming > finally > > > "click" for me, and now I realize how incredibly powerful it is. I was > > > able > > > to make something even better than I'd hoped for. > > > > > > Once I realized how easily you can just manipulate the AST, I made > this > > > really simple version which I didn't particularly like: > > > # Usage: > > > # function(x::Int, @Optional(y, MyType)) > > > macro Optional(name, ptype) > > > > > > Expr(:kw, :($name::Union(Nothing, $ptype)), nothing) > > > > > > end > > > > > > Then I was able to develop a flexible macro that better supports the > > > standard syntax, and I think is rather elegant: > > > # Flag a function argument of any type as optional by generating a > Union. > > > # If a default value is not defined, it assumes "nothing". > > > # Usage: > > > # function(x::Int, @maybe y::MyType) > > > # function(x::Int, @maybe y::MyType=someval) > > > macro maybe(argexpr) > > > > > > default = nothing > > > if argexpr.head == :(=) > > > > > > argexpr, default = argexpr.args > > > default = eval(default) > > > > > > end > > > @assert argexpr.head == :(::) > > > name, ptype = argexpr.args > > > deftype = typeof(default) > > > Expr(:kw, :($name::Union($deftype, $ptype)), default) > > > > > > end > > > > > > This is exactly the type of thing I was hoping to be able to do with > > > Julia; I'm certainly going to try to make it my goto language over > python > > > now. > > > > > > On Thursday, May 8, 2014 11:06:11 AM UTC-4, Pierre-Yves Gérardy wrote: > > >> On Friday, February 21, 2014 9:36:07 PM UTC+1, Joosep Pata wrote: > > >>> #2) def. value in expression, does not work > > >>> ex = :(x=1) > > >>> q = quote > > >>> > > >>> function f2($ex) > > >>> > > >>> x > > >>> > > >>> end > > >>> > > >>> end > > >>> println("does not work") > > >>> macroexpand(q)|>println > > >>> eval(q) > > >>> f2()|>println > > >>> ~~~ > > >>> > > >>> 2) gives me > > >>> > > >>> > ERROR: syntax: "x=1" is not a valid function argument name > > >> > > >> It works if you define ex as :(f(x=1)).args[2]. While superficially > > >> identical, your expression is a :(=), while this one is a :kw. > > >> > > >> —Pierre-Yves >
