A workaround for JuliaLang/julia#15276, for julia-1.x,
somewhat in the spirit of FastAnonymous.jl. Provides the @closure macro,
which wraps a closure in a let block to make reading variable bindings private
to the closure. In certain cases, this make using the closure - and the code
surrouding it - much faster. Note that it's not clear that the let block
trick implemented in this package helps at all in julia-0.5. However, julia-0.5
compatibility is provided for backward compatibility convenience.
@closure closure_expressionWrap the closure definition closure_expression in a let block to encourage
the julia compiler to generate improved type information. For example:
callfunc(f) = f()
function foo(n)
for i=1:n
if i >= n
# Unlikely event - should be fast. However, capture of `i` inside
# the closure confuses the julia-0.6 compiler and causes it to box
# the variable `i`, leading to a 100x performance hit if you remove
# the `@closure`.
callfunc(@closure ()->println("Hello \$i"))
end
end
endHere's a further example of where this helps:
using FastClosures
# code_warntype problem
function f1()
if true
end
r = 1
cb = ()->r
identity(cb)
end
# code_warntype clean
function f2()
if true
end
r = 1
cb = @closure ()->r
identity(cb)
end
@code_warntype f1()
@code_warntype f2()