I'm trying to give the `flvector-map' function a sensible type. A
stubbed-out attempt follows, along with an application of it that fails
typechecking.
#lang typed/racket
(require racket/flonum)
(: flvector-map
(case-> ((Flonum -> Flonum) FlVector -> FlVector)
((Flonum Flonum Flonum * -> Flonum)
FlVector FlVector FlVector * -> FlVector)))
(define flvector-map
(case-lambda
[(f xs) (error 'unimplemented)]
[(f xs ys . zss) (error 'unimplemented)]))
(flvector-map fl+ (flvector 1.0) (flvector 2.0))
This works fine:
(flvector-map + (flvector 1.0) (flvector 2.0))
I assume it's because `+' takes any number of arguments, but `fl+' takes
exactly two.
I've written fully polymorphic map-like functions before, using `...',
for which applying a binary function was no problem. (See `array-map' in
the `math/array' docs.) The first thing I tried, then, was using `...'
without type variables, but that doesn't work.
Is there a way to spell the type I want here?
Neil ⊥
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