On 30/10/2023 15:50, ceving wrote:
> Marc Nieper-Wißkirchen schrieb am Montag, 30. Oktober 2023 um 15:05:05 UTC+1:
>> Because there are at least two different `begin's.
>
> Wow: one symbol with two different meanings. This sounds broken.

I think it's because (lambda...) is a way to construct a value, and
(begin...) is a way to sequence actions.

The term 'lambda' as it applies to logic was described by a group of
logicians working on systems in general that might not have an atom for
*unspecified* so helpfully in scheme if you are to use lambda and return
*unspecified* you must do so by explicitly defining the value of the
lambda in term of something that may be *unspecified*. It's possible the
scheme language designers didn't appreciate the meaning in logic but
just followed habits of their forebears.

Some languages incorporate a lambda more wrongly and allow an implicit
*unspecified* because they're actually incorporating a stateful monad
because they followed *fewer* habits of their forebears.

cf. imperative vs pure functional languages.

On Sat, 2 Mar 2024 13:18:01 +0000, Tristan Wibberley wrote:

> The term 'lambda' as it applies to logic was described by a group of
> logicians ...

λ-calculus was first created by Alonzo Church. This was around the same
time Alan Turing formulated his “Turing machine” to represent computation.
The two theories turned out to be equally capable in this regard.

λ-calculus also offers an interesting way to deal with paradoxes, of the
kind that scare mathematicians so much: it represents them as an endless
loop. This is something we are well familiar with in computer science, and
it’s not something that scares us.