Re: [Bug-apl] Feature suggestion: multiple function arguments

[Juergen Sauermann]

Hi Kacper,

yes. The tricky case is when it cannot be decided if g is an operator or not.

Consider this:

      1 (+//) 1 2 3 4
1 2 3 4

We get the same result in GNU APL and IBM APL2. No idea what Dyalog
APL returns in this case.

The +// can then be interpreted in two different ways:

a)    function-plus  operator-reduce operator-reduce
b)    function-plus function-compress function-compress

Of course one could resolve this by deciding for either a) or b).
But: if we go for b) then we introduce an incompatibility with IBM APL2,
and if we go for a) then we have a syntax with exceptions for / \ ⍀ and ⌿.

I consider both options as really really bad and not worth the effort for implementing
them.

/// Jürgen

On 03/13/2016 07:35 PM, Kacper Gutowski wrote:

On Sun, Mar 13, 2016 at 6:20 PM, Juergen Sauermann
<address@hidden> wrote:

it actually does create conflicts.

In IBM APL2 and in GNU APL, the _expression_

⍺ (f g h) ⍵

gives a 3 item vector with the items being ⍺, (f g h), and ⍵.
In Dyalog APL it gives (quote):

(⍺ f ⍵) g (⍺ h ⍵) ⍝ dyadic (fgh) fork

I'm not certain whether it does create conflicts or not in general,
but I think this particular example is flawed: ⍺ (f g h) ⍵ could be
anything depending on what name classes those symbols have
(particularly if g were an operator).  When f, g, and h are all
functions, then it's not a vector, but a syntax error.  No conflict
here.

-k