Julia macro to generate iterator versions of collection functions

iterize.jl

using Devectorize

macro makeiter(func, name)
    expr = quote
        immutable $name{X}
            x::X
        end

        Base.start(i::$name) = start(i.x)
        Base.next(i::$name, s) = ((v, s) = next(i.x, s); ($func(v), s))
        Base.done(i::$name, s) = done(i.x, s)
        $name
    end
    return esc(expr)
end

macro iterize(oex)
    if isa(oex, Symbol)
        function ident(x) x end
        funcname = string(func)
        safename = gensym("iterate_$funcname")
        iter = @eval @makeiter(ident)
        return quote
            function ident(x) x end
            $iter($oex)
        end
    end

    local emptyA = Int[]
    ex, iters = oex, Expr[]
    while ex.head == :call
        func, second = ex.args[1:2]

        rettype = @eval $func($emptyA)
        makesarray = isa(rettype, AbstractArray)
        if makesarray
            funcname = string(func)
            safename = gensym("iterate_$funcname")
            iter = @eval @makeiter($func)
            push!(iters, iter)
            ex.args[1] = symbol(name)
        end

        !isa(second, Expr) && break || (ex = ex.args[2])
    end

    expr = quote
        $oex
    end
    prepend!(expr.args, iters)
    return expr
end

@makeiter abs iabs
@makeiter floor ifloor
@makeiter ceil iceil

function test()
    A = randn(1<<26)
    @time @devec x = sum(abs(A))
    @time sum(abs(A))
    @time sum(iabs(A))
    @time sumabs(A)

    println(sum(abs(A)))
    println(sum(iabs(A)))
    println(sumabs(A))

    @time sum(ceil(floor(abs(A))))
    @time sum(iceil(ifloor(iabs(A))))
    @time @devec x = sum(ceil(floor(abs(A))))
    println(sum(ceil(floor(abs(A)))))
    println(sum(iceil(ifloor(iabs(A)))))
end

test()