Lambda efficiency

Lambda efficiency

[Michael Lucy]

Hey,

I'm generating some code, and I was wondering if:
((lambda (x) (* x 2)) 3)
is significantly less efficient than:
(* 3 2)
or if the Guile compiler will take care of that for me (the expression
is going to be evaluated a lot).

Re: Lambda efficiency

[Andy Wingo]

Heya,

On Tue 22 Jun 2010 21:18, Michael Lucy <MichaelGLucy@Gmail.com> writes:

> I'm generating some code, and I was wondering if:
> ((lambda (x) (* x 2)) 3)
> is significantly less efficient than:
> (* 3 2)

((lambda (x) y) z) is reduced to (let ((x z)) y) at compile-time. We
don't inline x yet, though we will soon.

Verily:

scheme@(guile-user)> ,c ((lambda (x) (* x 2)) 3)
Disassembly of #<objcode 8b98968>:

   0    (assert-nargs-ee/locals 8)      
   2    (make-int8 3)                   ;; 3
   4    (local-set 0)                   
   6    (local-ref 0)                   
   8    (make-int8 2)                   ;; 2
  10    (mul)                           
  11    (return)                        

scheme@(guile-user)> ,c (* 2 3)
Disassembly of #<objcode 8eac318>:

   0    (assert-nargs-ee/locals 0)      
   2    (make-int8 2)                   ;; 2
   4    (make-int8 3)                   ;; 3
   6    (mul)                           
   7    (return)                        

Andy
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