After the posting of the tune by Henrik a lot of positive reactions were posted in this thread. I just quote some of them that were focussed on the key (or mode) of the tune:
Starting with scales of A, I could not find any match. With scales of D there is a match with D melodic minor (ascending), which is (as far as I know) quite different from plain Dminor.
So David is right, but it's a very special D minor
I think it's more accurate to say that this is just an example of a tune (in fact, a tradition) that cannot be accurately described by a terminology that was derived from traditions or musical examples which didn't include such "scales", "modes", or whatever. Even more "impossible" are Swedish tunes that consistently include both "major" and "minor" variants of a particular degree of the scale. A, B, (C, C#), D, E, F, G
is a not-uncommon example.
Is it an 8-note "scale", rather than the usual Western 7-note "diatonic" scale? No, because the sequences C-C# and C#-C never
occur. Some note sequences will include C# (usually with an A chord, if
chords are used) and others will include C natural (with a C chord, not
Am). But aside from the "harmonic minor" concept -- where the ascending
scales are different -- I don't think there's anything in standard "music theory" for describing a music in which different variants of a single degree of the scale are given equal weight. Always the one is "the" note of the scale, and the other is treated as an aberration, or "accidental".
I think that in such Swedish tunes a distinction should be made between the collection of notes used in the primary structure of the tune and the sub-collections of notes which may potentially be used in a single sequence. In standard music theory these are one and the same, and are known as the "scale", but not so in my above example. There both C and C# are fundamental, and one could potentially have either B-C-D or B-C#-D as a sequence... but never
Does Sweden have it's own music-theory terminology for describing such tunes? I don't know. I guess I should ask some of my Swedish friends. I believe David Barnert once mentioned that klezmer musicians do have their own names for the various non-"Western" scales (the Western ones, too?) that they play, so maybe they
have a name for the Guckulåt scale. But does even klezmer music have scales where major and minor intervals have equal status?