[m-users.] alternate pairs syntax?

[nll at dent.vctlabs.com]

Thank you.
Indeed I missed that.

Nick Lockwood


On Mon, 9 Nov 2015, Matthias Güdemann wrote:

> Hi Nick,
>
>> The problem here is the usage of "->"
>
>> I cannot find in the documntation this operator used to express the
>> pair constructor.  I expected to see some pairs defined in this
>> context.  Is this another way to talk about pairs? or am I missing out
>> on what is going on?
>
> This seems to be the function '->' defined as follows
>
> ,----
> |    % Utility operator to create lexemes.
> |    %
> | :- func (T1 -> token_creator(Tok)) = pair(regexp, token_creator(Tok))
> |             <= regexp(T1).
> `----
>
> in lex.m:192 
>
> It is probably a bit unfortunate that is uses the same operator as the
> if-then-else.
>
> Matthias
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