I see that we now have is_list(), is_num(), is_bool(), and is_string(), but
there is no is_range.  It seems like maybe right now you can write

function is_range(x) = !is_list(x) && !is_num(x) && !is_bool(x) &&
!is_string(x), but I'm not sure if I've missed anything, and this seems kind
of clumsy.  Also it's problematic down the road if a new type is ever added.

Have I missed something here?

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function is_range(A) = is_num(A[0]) && !is_list(A);

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A range checker needs to fulfill:

-- a list of all numbers
-- same distance for all i~i+1 pairs
function is_range(o, _d, _i=0){  _i==0?    ( is_num(o[0]) && is_num(o[1])?
is_range( o, _d= o[1]-o[0], _i=1)      : false      )      : _i<length-1?
( is_num(o[i+1]) && _d != o[i+1]-o[i] ? false    : is_range( o,
_d=_d, _i=_i+1)        )  : true}</pre>
This code has not been tested yet.

$  Runsun Pan, PhD $ libs: scadx , doctest , faces ( git ), offline doc ( git ), runscad.py ( 2 , git ), editor of choice: CudaText  ( OpenSCAD lexer ); $ Tips ; $ Snippets

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My apology to the group for the wrong syntax in my previous post. I have been
working on javascript intensively and mess it up in my head with the syntax
of OpenSCAD. Here is the correct and tested one:
function is_range(o, _d, _i=0) =(  _i==0?    ( isnum(o[0]) && isnum(o[1])?
is_range( o, _d= o[1]-o[0], _i=1)      : false      )      : _i<len(o)-1?
( isnum(o[_i+1]) && _d != o[_i+1]-o[_i] ? false    : is_range( o,
_d=_d, _i=_i+1)        )  : true );</pre>Test:
| 0> is_range([2:6])= true| 1> is_range([2:2:10])= true| 2>
is_range([1,2,3])= true| 3> is_range([1,2,3,5])= false| 4> is_range("abc")=
false

$  Runsun Pan, PhD $ libs: scadx , doctest , faces ( git ), offline doc ( git ), runscad.py ( 2 , git ), editor of choice: CudaText  ( OpenSCAD lexer ); $ Tips ; $ Snippets

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