gistfile1.txt

Benchmark: ran giterate0, giterate0-1, giterate0-2, giterate0-3, giterate1, giterate1-1, giterate1-2, giterate2, each for 10 times.
    giterate0: 6.322 real, 6.310 cpu (6.300 user + 0.010 sys)@1.58/s n=10
  giterate0-1: 6.336 real, 6.320 cpu (6.320 user + 0.000 sys)@1.58/s n=10
  giterate0-2: 6.583 real, 6.560 cpu (6.560 user + 0.000 sys)@1.52/s n=10
  giterate0-3: 6.538 real, 6.520 cpu (6.520 user + 0.000 sys)@1.53/s n=10
    giterate1: 7.110 real, 7.110 cpu (7.110 user + 0.000 sys)@1.41/s n=10
  giterate1-1: 7.004 real, 7.010 cpu (7.010 user + 0.000 sys)@1.43/s n=10
  giterate1-2: 6.564 real, 6.560 cpu (6.560 user + 0.000 sys)@1.52/s n=10
    giterate2: 5.977 real, 5.980 cpu (5.980 user + 0.000 sys)@1.67/s n=10

              Rate giterate0 giterate0-1 giterate0-2 giterate0-3 giterate1 giterate1-1 giterate1-2 giterate2
    giterate0  2/s        --       1.002       1.040       1.033     1.127       1.111       1.040     0.948
  giterate0-1  2/s     0.998          --       1.038       1.032     1.125       1.109       1.038     0.946
  giterate0-2  2/s     0.962       0.963          --       0.994     1.084       1.069       1.000     0.912
  giterate0-3  2/s     0.968       0.969       1.006          --     1.090       1.075       1.006     0.917
    giterate1  1/s     0.887       0.889       0.923       0.917        --       0.986       0.923     0.841
  giterate1-1  1/s     0.900       0.902       0.936       0.930     1.014          --       0.936     0.853
  giterate1-2  2/s     0.962       0.963       1.000       0.994     1.084       1.069          --     0.912
    giterate2  2/s     1.055       1.057       1.097       1.090     1.189       1.172       1.097        --

t.scm

(use gauche.time)
(use gauche.generator)

(define (giterate0 f x)
  (^[]
    (begin0 x
      (set! x (f x)))))

(define (giterate0-1 f x)
  (^[]
    (rlet1 x_ x
      (set! x (f x)))))

(define (giterate0-2 f x)
  (let ((x_ x))
    (^[]
      (set! x_ x)
      (set! x (f x))
      x_)))

(define (giterate0-3 f x . dummy)
  (^[]
    (if (null? dummy)
      (set! dummy #t)
      (set! x (f x)))
    x))

(define (giterate1 f x)
  (gcons* x
          (^[]
            (set! x (f x))
            x)))

(define (gcons1 item g)
  (define (gen)
    (set! gen g)
    item)
  (^[] (gen)))

(define (giterate1-1 f x)
  (gcons1 x
          (^[]
            (set! x (f x))
            x)))

(define (giterate1-2 f x)
  (let ((first #t)
        (x x))
    (^[] (if first
           (begin (set! first #f) x)
           (begin (set! x (f x)) x)))))

(define (giterate2 f x)
  (^[]
    (set! x (f x))
    x))

(define (runner proc)
  (^[] ((gdrop (proc (cut + 1 <>) 1) 10000000))))

(define (main args)
  (time-these/report
   10
   `((giterate0   . ,(runner giterate0))
     (giterate0-1 . ,(runner giterate0-1)) 
     (giterate0-2 . ,(runner giterate0-2))
     (giterate0-3 . ,(runner giterate0-3))
     (giterate1   . ,(runner giterate1))
     (giterate1-1 . ,(runner giterate1-1))
     (giterate1-2 . ,(runner giterate1-2))
     (giterate2   . ,(runner giterate2))
     )))