[isabelle-dev] NEWS: parameterized antiquotations @{map N}, @{fold N} etc.

Makarius makarius at sketis.net
Mon Nov 3 10:08:09 CET 2014

On Thu, 30 Oct 2014, Florian Haftmann wrote:

>>>> Isabelle/ML has antiquotations as some kind of macro language.  It can
>>>> do certain things better than the C preprocessor, although one always
>>>> needs to be careful to stay within reason.
>>> How about this?
>>>   ap2 f (x, y) = (f x, f y)
>>>   @{ap n} f (x1, ..., xn) = (f x1, ..., f xn)
>>> Maybe even this as well?
>>>   @{ap n(k)} f (x1, ..., xn) = (x1, ..., f xk, ..., xn)
>>> That might be occasionally useful to map field 1, or 2, or 3 of a triple:
>>> @{ap 3(1)}, @{ap 3(2)}, @{ap 3(3)}.  The existing combinators apfst,
>>> apsnd fit into the same scheme.
> Both have there uses.  I am not sure whether »ap« is the right name.
> »apfst« and »apsnd« are of course old-standing items, but when something
> new enters the stage further thoughts should be spent.  Must confess I
> have no better proposal at hand.  Or maybe »apply«?.

Larry, you have introduced the "pairself" name some decades ago.  How do 
you feel about it being called "ap2" or "apply2"?


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