C reads a following object, which must be a list of length two whose elements are both reals.

I don't see that "a following object" disallows the space.

Would be fine If we just could customize eclector not to signal an exception here

scymtym commented 3 years ago

I agree that the description sounds as if whitespace is fine, but there are some unclear aspects:

The printed representation is described without optional whitespace:

22.1.3.1.4 Printing Complexes

A complex is printed as #C, an open parenthesis, the printed representation of its real part, a space, the printed representation of its imaginary part, and finally a close parenthesis.
Sharpsign S which has a similar structure is specified in a different way which suggests that whitespace is not accepted. SBCL, for example, indeed does not accept whitespace after #S.
Interpreting "a following object" as skipping over non-objects would also make #C #|foo|# (1 2) and #C #-sbcl :foo (1 2)legal (and SBCL, for example, indeed accepts it). Such an input would lead to a strange concrete syntax tree.

So maybe the best solution is customizable behavior as you suggest.

scymtym commented 3 years ago

s-expressionists / Eclector