user-defined operators

Ulf Wiger <>
Wed Mar 24 22:40:53 CET 2004


On Sun, 21 Mar 2004 09:06:56 -0800 (PST), Thomas Lindgren 
<> wrote:

> Some time ago there was interest in extending Erlang
> with your own operators, e.g., !!. So why not provide
> them?
> Here is a code sketch for extending Erlang to permit
> simple user-defined infix operators `op`. The idea is
> basically taken from Haskell and seems fairly clean. I
> used backquotes around the operator because Haskell
> did so.
> I modified the erlang parser and scanner to support
> this notation; it seems to work, though I haven't used
> it very extensively.
> f(X, Y) -> X `foo` Y.   %% note: foo is "backquoted"
> is parsed as if:
> f(X,Y) -> 'foo'(X,Y).   %% call function foo/2
> The operator `op` has the same precedence as
> andalso/orelse. You can also write `mod:func` to
> invoke mod:func(X,Y), e.g.,
>    Port `erlang:port_command` Data

So is your suggestion that one would write e.g.

   -import(sys, ['!!'/2,]).

   fetch(Host, File) ->
      Host `!!` {get, File}.

?

/Uffe

-- 
Ulf Wiger, Senior System Architect
EAB/UPD/S

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