Deforesting racket/list

[countvajhula]

@dzoep made a survey of racket/list and identified these APIs as candidates for deforestation (after the initial compiler release merging #74 ).

Consumers:

• [ ] cadr, caddr, cadddr, caddddr, cadddddr
• [ ] list-ref
• [ ] length
• [ ] reverse (like foldX)
• [ ] findf
• [ ] assoc
• [ ] assw
• [ ] assv
• [ ] assq
• [ ] assf
• [ ] empty? / null?
• [ ] pair? / cons?
• [ ] index-of
• [ ] index-where
• [ ] count
• [ ] argmin
• [ ] argmax

Producers:

• [ ] map
• [ ] ormap
• [ ] andmap
• [ ] append
• [ ] append*
• [ ] inclusive-range

Transformers:

• [ ] ormap
• [ ] andmap
• [ ] list-tail, drop
• [ ] remove
• [ ] remq
• [ ] remv
• [ ] remw
• [ ] remove*
• [ ] remq*
• [ ] remv*
• [ ] remw*
• [ ] member (tail can continue to be processed)
• [ ] memw
• [ ] memv
• [ ] memq
• [ ] memf
• [ ] cdr, cddr, cdddr, cddddr, cdddddr, rest
• [ ] list-update
• [ ] list-set
• [ ] indexes-of
• [ ] indexes-where
• [ ] take
• [ ] takef
• [ ] dropf
• [ ] add-between
• [ ] filter-map
• [ ] filter-not
• [ ] remf
• [ ] remf*

[countvajhula]

As part of this effort, we'd likely want to include the other interfaces mentioned in St-Amour's writeup: unfoldr, zip and average.

[countvajhula]

Also as discussed in Qi meetings, it may make sense to prototype map1 (analogous to compose1) for possible addition to Racket, as part of this effort.

[countvajhula]

Another note from meetings: review the use of contracts (vs manually constructed exceptions or blame objects) in deforestation for any additional performance gains.

[countvajhula]

Another thing to follow up on: Should Qi provide a map utility that supports multiple (or zero) return values? E.g. (map (flow (when positive? (-< _ _))) (list 1 2 3 4 5).