Re: [stack] array theory question

John Nowak scripsit:

> What I'm hoping might make sense here is making the atom 'y'  
> equivalent to '{y}'. This would allow the second form of '&' shown  
> above to be used in the general case. Do you think that may be  
> workable? Is it comparable to what Nial or APL do?

Ah^2.  What you want is Algol 68's "rowing coercion" ("row" being A68
jargon for vector, or 1-D array).  This coercion transforms a non-row
value into the corresponding row value with one element.  It's applicable
only where the type is uniquely known at compile time: in A68 jargon,
in the following "strong contexts":

o	the actual parameters of a function call
o	a type cast
o	the RHS of an assignment, contant declaration, or variable
	declaration with an initializer
o	the body of a procedure (which is an expression in A68)
o	all the arms of an if- or case-expression except one
o	either side, but not both, of an identity expression

It's interesting note that A68, as of the Revised Report, has two kinds
of 2-D arrays:  "row row of <whatever>", which is a C-style rectangular
matrix, and "row of row of <whatever>", which is a Java-style vector of
pointers to vectors.  (These are the names of the types, not the way you
write them in declarations.)  Consequently, there are four kinds of 3-D
arrays, and in general 2^(k-1) kinds of rank-k arrays.

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John Cowan      [email protected]      http://www.ccil.org/~cowan