deal with non-standard evaluation about rcall.jl HOT 9 OPEN

macro rplot(x,y,args...)
    :(rcall(:plot,$x,$y,xlab=$(string(x)),ylab=$(string(y)),$args...))
end

julia> macroexpand(:(@rplot(x,sin(x))))
:(rcall(:plot,x,sin(x),xlab="x",ylab="sin(x)",()...))

using RCall
using RDatasets
mtcars = dataset("datasets", "mtcars");
rprint(rcall(:lm, "Disp~MPG", data=mtcars))

julia> rprint(rcall(:lm, "Disp~MPG", data=mtcars))

Call:
lm(formula = "Disp~MPG", data = structure(list(Model = c("Mazda RX4", 
"Mazda RX4 Wag", "Datsun 710", "Hornet 4 Drive", "Hornet Sportabout", 
"Valiant", "Duster 360", "Merc 240D", "Merc 230", "Merc 280", 
.
.
.
4L, 4L, 4L, 4L, 3L, 3L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 3L, 3L, 3L, 
3L, 3L, 4L, 5L, 5L, 5L, 5L, 5L, 4L), Carb = c(4L, 4L, 1L, 1L, 
2L, 1L, 4L, 2L, 2L, 4L, 4L, 3L, 3L, 3L, 4L, 4L, 4L, 1L, 2L, 1L, 
1L, 2L, 2L, 4L, 2L, 1L, 2L, 2L, 4L, 6L, 8L, 2L)), .Names = c("Model", 
"MPG", "Cyl", "Disp", "HP", "DRat", "WT", "QSec", "VS", "AM", 
"Gear", "Carb"), class = "data.frame", row.names = c(NA, 32L)))

Coefficients:
(Intercept)          MPG  
     580.88       -17.43  

using RCall
RCall.rgui_start()

macro promise(x)
    sym = Expr(:quote, symbol(string(x)))
    quote
        RCall.preserve(sexp(ccall((:R_mkEVPROMISE,libR),Ptr{Void},(Ptr{Void},Ptr{Void}), sexp($sym), sexp($x))))
    end
end

x = linspace(0,pi,10)
rcall(:plot, (@promise x), (@promise sin(x)))

reval("""
       f <- function(x) substitute(x)
       g <- function(x) match.call()
""");
rprint(rcall(:f, @promise x))  
# x
rprint(rcall(:g, @promise x))
# g(x = c(0, 0.111111111111111, 0.222222222222222, 0.333333333333333, 
# 0.444444444444444, 0.555555555555556, 0.666666666666667, 0.777777777777778, 
# 0.888888888888889, 1))

macro lazy(expr)
    blk = Expr(:block)
    cleanup = Any[]
    push!(blk.args,:(env = newEnvironment(rGlobalEnv)))
    (expr.head == :call && expr.args[1] == :rcall) || error("expect rcall(f, args...)")
    args = copy(expr.args)
    shift!(args)
    for (i,a) in enumerate(args)
        if typeof(a) == Symbol
            push!(blk.args,:(env[$(QuoteNode(a))] = sexp($(esc(a)))))
            args[i] = QuoteNode(a)
            push!(cleanup,:(env[$(QuoteNode(a))] = rNilValue))
        elseif typeof(a) == Expr && a.head == :kw && typeof(a.args[2]) == Symbol
            value = a.args[2]
            push!(blk.args,:(env[$(QuoteNode(value))] = sexp($(esc(value)))))
            args[i].args[2] = QuoteNode(value)
            push!(cleanup,:(env[$(QuoteNode(value))] = rNilValue))
        else
            args[i] = :($(esc(a)))
        end
    end
    ret_call = :(ret = reval(rlang_p(),env))
    append!(ret_call.args[2].args[2].args, args)
    push!(blk.args, ret_call)
    append!(blk.args, cleanup)
    push!(blk.args,:(ret))
    blk
end

julia> using RCall

julia> rmtcars = dataset("datasets", "mtcars");

julia> @lazy rcall(:lm, reval("as.formula('HP~MPG')"), data=rmtcars)
RCall.RObject{RCall.VecSxp}

Call:
lm(formula = HP ~ MPG, data = rmtcars)

Coefficients:
(Intercept)          MPG  
     324.08        -8.83