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A workaround forJuliaLang/julia#15276, for julia-1.x,somewhat in the spirit of FastAnonymous.jl. Provides the@closure macro,which wraps a closure in alet block to make reading variable bindings privateto the closure. In certain cases, this make using the closure - and the codesurrouding it - much faster. Note that it's not clear that thelet blocktrick implemented in this package helps at all in julia-0.5. However, julia-0.5compatibility is provided for backward compatibility convenience.

@closure closure_expression

Wrap the closure definitionclosure_expression in a let block to encouragethe julia compiler to generate improved type information. For example:

callfunc(f)=f()functionfoo(n)for i=1:nif 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"))endendend

Here's a further example of where this helps:

using FastClosures# code_warntype problemfunctionf1()iftrueend    r=1    cb= ()->ridentity(cb)end# code_warntype cleanfunctionf2()iftrueend    r=1    cb=@closure ()->ridentity(cb)end@code_warntypef1()@code_warntypef2()