[eeps] Proposal for /\ and \/ operators
Raimo Niskanen
<>
Thu Feb 26 10:35:58 CET 2009
On Thu, Feb 26, 2009 at 12:45:42PM +1300, Richard O'Keefe wrote:
> I'm sick of writing my own max and min functions.
> Aren't you?
>
Yes me too...
:
>
> Specification
>
> Currently the Erlang language has no built-in support for
> the maximum and minimum operations. So we add
>
> /\ with the same precedence and associativity as band
> \/ with the same precedence and associativity as bor
>
> E1 /\ E2 has the same effects and value as
> (T1 = E1, T2 = E2, if T1 > T2 -> T2 ; true -> T1 end)
> E1 \/ E2 has the same effects and value as
> (T1 = E1, T2 = E2, if T1 > T2 -> T1 ; true -> T2 end)
Can you explain to a non-mathematician (me) why you have defined
(E1 /\ E2) as min(E1, E2) and
(E1 \/ E2) as max(E1, E2). To me it seems counterintuitive
since /\ looks like a mountain hence max
and \/ looks like a valley hence min.
And I do not want to fully understand Lattice theory
to understand which operator is which. I am a simple programmer.
Since (1.0 == 1) and (1.0 >= 1) and (1 >= 1.0),
could you also for /\ and \/ elaborate on
max(A, B) when A >= B -> A;
max(A, B) -> B.
vs
max(A, B) when A > B -> A;
max(A, B) -> B.
Which may be most useful in the light of operator
precedence and binding?
--
/ Raimo Niskanen, Erlang/OTP, Ericsson AB
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