> As far as I understood, optimizer somehow cannot get the result of `apply`.
> Maybe we should replace `compose` with case-lambda version (for 5-10 args at
> least)?
Changed to
(define compose
(case-lambda
[() identity]
[(f) (lambda (x) (f1 x))]
[(f1 f2) (lambda (x) (f1 (f2 x)))]
[(f1 f2 f3) (lambda (x) (f1 (f2 (f3 x))))]
[(f . fs) (cond
[(null? fs) f]
[else
(define rest-f (apply compose fs))
(lambda (x) (f (rest-f x)))])]))
(define f-comp (apply compose (list f1 f2 f3)))
Still fast.
If change `compose` to only recurse
(define (compose f . fs)
(cond
[(null? fs) f]
[else
(define rest-f (apply compose fs))
(lambda (x) (f (rest-f x)))]))
then (compose f1 f2 f3) is slow.
But, if manually unroll recursive `compose` and set
(define f-comp (lambda (x) (f1 ((lambda (x) (f2 (f3 x))) x)))
then again fast.
Now I again don't understand why.
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