Add system.$(HSlice) and fix #7898

[metagn]

No description provided.

[kaushalmodi]

Can you please add spaces on both sides of ..? It looks cleaner in my opinion.

So $(1 .. 5) will output "1 .. 5".

[mratsim]

I'm skeptical about having $(23, 45) print (Field0: 23, Field1: 45)

That leaks implementation details (that unnamed field are named Field0, Field1), and is just ugly.

So was the example showing what was intended or was it just wrong?

Note: I think the $ for HSlice should have been in a separate PR as that would avoid blocking it for unrelated discussion on $tuple

[mratsim]

Wouldn't the proper fix be something like:

func `$`(x: tuple): string =
  result = "("
  for idx, val in fieldPairs(x):
    if idx != 0:
      result.add ", "
    result.add $val
  result.add ')'

(untested)

[dom96]

This would lose information for named tuples.

[drslump]

IMO the optional names in tuples are aliases to ease writing and reading code, the tuple model however remains as an ordered list of N values. So for creating a string representation I would ignore the names and just dump the values. Another thing would be for debugging (repr), in which case it should output the field names.

[alehander92]

@drslump please, consider ignoring them only when they start with Field0: this way you'll have a nice repr for both kinds of tuples 98% of the time

[drslump]

My thinking is that $ means to string, it should not leak implementation details.

Has it been considered to introduce a $$ operator convention to generate a print-debug oriented to-string?

[krux02]

@drslump nope there is no $$ operator. The $ operator is already for print-debug.

[Araq]

marshal.nim has a $$ operator. :-)

[timotheecour]

please, consider ignoring them only when they start with Field0

isNamedTuple (see my suggested implementation here #10010 (comment)) is more robust than checking if they start with Field0 as it relies on compiles(t.Field0), which would be false for unnamed tuple even if it has a field "Field0" (and also more efficient, since only 1st field needs to be checked)

[timotheecour]

=> PR #10070