Note that for non-recursive lets
let' x1 = e1
x2 = e2
is sequential and *not* the same as the parallel
let' (x1, x2) = (e1, e2)
The first is
(\ x1 -> (\x2 -> ...) e2) e1
and the second is
(\ (x1,x2) -> ...) (e1, e2)
On 11.07.2013 13:36, Doug McIlroy wrote:
By analogy to ML, which has "let" and "let rec", where the latter
corresponds to Haskell's "let", one is led to "let nonrec". I
would definitely not like "shadow", for it means that new
variable does NOT cast a shadow on its definining expression.
I fear also that "let nonrec" by any name would introduce another
attractive nuisance, just as insidious as the one it is intended
to correct. For example
x = ...
let nonrec { x = someFunction x
xsq = x^2} in ...
won't do what was probably intended. In my own code, this idiom
is more likely than the one that sparked the discussion.
Doug
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Andreas Abel <>< Du bist der geliebte Mensch.
Theoretical Computer Science, University of Munich
Oettingenstr. 67, D-80538 Munich, GERMANY
andreas.a...@ifi.lmu.de
http://www2.tcs.ifi.lmu.de/~abel/
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