Allen's lambda syntax proposal

David-Sarah Hopwood david.hopwood at
Fri Dec 5 17:08:38 PST 2008

Breton Slivka wrote:
> On Fri, Dec 5, 2008 at 7:49 AM, David-Sarah Hopwood
> <david.hopwood at> wrote:
>> Mark S. Miller wrote:
>>> [...] "\" has taken the lead....
>> There's still #, @, and ` (and of course keywords like lambda and fn).
>> None of these are as mnemonic as \, but they leave \ as a purely
>> lexical escape character.
>> It's quite ironic that we are still limited, as Church was, in
>> which characters we can use for the modern equivalent of
>> "typographical reasons".
> this may be a stupid question, but why? Is it really so impossible to
> have λ(a,b,c){}  ?
> You guys seem to have no trouble typing it.

To type λ, I usually have to cut-and-paste it from somewhere else,
which is quite inconvenient. But more importantly, having a
non-US-ASCII character in the basic syntax means that parsing is
dependent on recognising character encoding accurately. In practice,
that is very hit-and-miss, with files' encoding often being labelled
or guessed incorrectly. Currently, the effects of this are restricted
to programs that use non-US-ASCII characters in strings without
escaping, and therefore only the files containing such programs have
to be labelled accurately.

(I wish it weren't so, and often the reason why it is so is inexcusably
poor attention to standards by application writers, but we have to be

David-Sarah Hopwood

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