[Haskell-cafe] What's the story behind "applicative" in "Constant Applicative Form"?

Stephen Tetley stephen.tetley at gmail.com
Mon Jan 29 22:18:49 UTC 2018

Hi Sonne

Circa the 1970s and 80s "applicative" was often used in the UK as a
synonym for functional, and its coinage dates back to at least
Landin's "The Next 700 Programming Languages" paper (1966). I wouldn't
bet against "applicative form" being the same thing as "applicative
expressions" in Landin's paper, though I have to confess this section
goes over my head.

I thought I'd read that researchers in the 70s and 80s preferred the
term "applicative" over "functional" because "functional" can also be
a synonym for "working" (rather than "not-working"), but I'm not sure
how how much currency "functional" actually had in those days.

I suspect "constant non-applicative form" is a misnomer - I would
guess the opposite of "CAF" would be "non-constant applicative form".

Best wishes


On 29 January 2018 at 16:21, sonne <kindaro at gmail.com> wrote:
> Hi cafe.
> I've been trying to make the concept of CAFs get through to me, but
> the very name is cryptic enough to stupefy me. What does it mean for a
> thing to be "applicative"? Is it related to the concept of applicative
> functor (likely not)? What would a constant non-applicative form look
> like? A non-constant applicative form? An applicative non-form, in the
> end?
> I put a question on Stack Overflow about this, only to discover no
> one's really sure. I would appreciate either an answer put there right
> away or a permission to re-post or rephrase an answer there myself,
> but, if you do mind, I will of course keep the answer private to this
> mailing list. This is the link to the question:
> stackoverflow.com/questions/48489778
> Thank you!
> P.S. I guess this is my first e-mail to this list, so please kindly
> let me know if it's unfit or in any way out of line.
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