[Re-added guile-devel# to CC] Stefan Israelsson Tampe schreef op zo 27-03-2022 om 16:37 [+0200]: > I mean that modul-ref is a hash-table lookup, and that's more > expensive as you say. I suggested that lexical variables should be > let bound > because you can deduce more things with them e.g. in > > (let ((a (@ x y))) > (when (vector? a) code ...)) > > Then a is known to be a vector and the check can be avoided inside > code ... > You suggest to use (@ x y) everywhere which is not terrible, > especially with wingo's recent work. But still not sure that all > optimisations work for referencing (@ x y) all the time.
I could do this, but: * this won't work for macros, so I would have to make a special case for them * the imported variables might not yet have been initialised. E.g.: (lambda () (use-modules/lexical (foobar)) a-foo ; initially #false (initialise-foobar!) a-foo) ; now 'footastic' The problem with your proposal is that modifications to global variables would not be detected --- the idea of 'use-modules' is to import the _variables_, not their current _values_. Additionally, doing the latter would be backwards-incompatible. * not all imported variables might be used, so your proposal might make things worse. E.g.: (define (foo) (use-modules (ice-9 exceptions)) (if (do-stuff) 'ok (raise (make-some-exception with variables from (ice-9 exceptions))))) In the normal case, the variables would not need to be dereferenced. * I just want to make lexical use-modules work and I'm not currently interested in (possibly futily) trying to squeezing out some extra % or ‰ of performance. > Would be nice though to be able to select the vars to be bound and > improve on compilation speed if there is a lot of baggage (large > module and only few var used) When making a patch for merging 'use-module/lexical' into 'use- modules', I intend to preserve support for #:select. Greetings, Maxime.
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