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Re: *-GET for dicts -- failure continuation versus default value

This page is part of the web mail archives of SRFI 44 from before July 7th, 2015. The new archives for SRFI 44 contain all messages, not just those from before July 7th, 2015.

Taylor Campbell wrote:
Scott and I seem to disagree on this.  Here's a log of our debate about it
on IRC tonight:  (I'm Riastradh; Scott is FoxFire)

<Riastradh> Dictionaries' *-GET should take an optional failure continuation, not default value.

I would very much like to see *any* kind of function (promise, continuation, procedure) there rather than simply a default value.

The use of exceptions is a popular style. Also there are more exotic applications such as using a secondary retrieval on a cache failure.

I believe a procedure taking the arguments supplied to the original call (whether fold, get, update), although a bit ugly, would easily support any application need without a performance penalty when simply providing a fixed default value.

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