symbolic list element as expression?

[dyc-emet]

Hi,
I noticed that right now the list element cannot be used as an expression, e.g.
a[i]
,in which a and i are just two symbols, will trigger an error.

[dyc-emet]

The expression is not supported and is supposed to trigger an error.

[jlapeyre]

Thanks. Yes, it is not supported. But I had considered a more user-friendly (Symata-level) error. For instance

symata 12> 3[4]
BoundsError("part specification 4 is longer than the depth of the object.", #undef)

Although the Symata-level error is no longer working as I want now. As you can see. It is thrown to Julia.

But, I think I did implement subscripted variables. I'll search for if/how I did it.

[jlapeyre]

You can use a(i). This is analogous to a[i] in Mathematica. And Symata a[i] is Mathematica a[[i]]. I think I have not yet implemented a(i), a(3), a(j) etc as a hash table, which would improve effciency. But, I'm not sure.

I'll open this again, because the error is exposing the implementation.

[jlapeyre]

More precisely, a[i] is supported. It is equivalent to Mathematica a[[i]]. But, if the "part specification is longer than the depth of the object", then an error is thrown.

symata 1> a[1]
BoundsError("part specification 1 is longer than the depth of the object.", #undef) ...

symata 1> b = [0]
Out(1) = [0]

symata 2> b[1]
Out(2) = 0

[jlapeyre]

Mathematica

In[1]:= Table[a[i], {i, 10}]

Out[1]= {a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8], a[9], a[10]}

Symata

symata 1> Table(a(i) , [i, 10])
Out(1) = [a(1),a(2),a(3),a(4),a(5),a(6),a(7),a(8),a(9),a(10)]