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Function Call Juxtaposition - Language Lawyer Question

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2015.07.07 06:50 PM

Here is another language lawyerly question:

Usual function call syntax is like : f[(p1;p2;p3)]

Then how does the interpreter know the recognize the following as a function call

f p1 p2 p3 ?

Then if you were to think about function in bigger complex expressions, the question becomes even more interesting ?

Is there an general way to figure these correct syntax / order of evaluation questions out ?

4 REPLIES 4

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2015.07.12 09:16 AM

f (p1;p2;p3) is the juxtaposition and is picked up by the parser.

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2015.07.14 01:09 AM

q){x+y}[0N!1;0N!2]

2

1

3

Also, not sure if you intended to call f[(p1;p2;p3)], or f[p1;p2;p3]. Note that those 2 are different, the first one takes 1 parameter, while the second takes 3. And as @Erik Friis mentioned your f p1 p2 p3 won't work.

On Tuesday, July 7, 2015 at 9:22:51 PM UTC-7, analyst wrote:

Here is another language lawyerly question:Usual function call syntax is like : f[(p1;p2;p3)]Then how does the interpreter know the recognize the following as a function callf p1 p2 p3 ?Then if you were to think about function in bigger complex expressions, the question becomes even more interesting ?Is there an general way to figure these correct syntax / order of evaluation questions out ?

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2015.07.14 09:06 AM

a[1][2][3]

This repeated item indexing expression is evaluated as:

((a[1]))[2])[3]

And expressions with multiple adverbs:

x @'' y

is evaluated as:

x (@')' y

But for the most part as José says the right to left order or evaluation is quite straightforward and one of the strong suits of q, k, j, and APL.

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2015.07.17 03:36 AM

Another example is evaluation of where clause in select statement: right to left evaluation inside each where clause, but left to right per comma separated condition

In analyst example f p1 p2 p3, it doesn't work just because 1 2 3 is being treated as a single parameter, it will work with dot operator applied: f . p1 p2 p3

Charles

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