> On 26 Apr, 2020, at 1:01 PM, David Kastrup <d...@gnu.org> wrote: > > Predicates used in argument parsing have to be "primary" in that they > have to deliver a result for anything thrown at them. >
Can that be noted in the docs (http://lilypond.org/doc/v2.19/Documentation/extending/scheme-function-definitions)? For a scheme novice (like myself) that distinction isn’t expected as the docs just point to the full list of predicates (http://lilypond.org/doc/v2.19/Documentation/notation/predefined-type-predicates) without noting that only primary ones will work in this context. Further, in that full list of predicates, the first two sections are clearly labeled as primary and secondary, but what about the other three? Clearly index? and ly:music? are primary (since they work in this context) so I suspect that all LilyPond scheme predicates (where index? appears) and LilyPond exported predicates (where ly:music? appears) are primary, but it would be nicer if that was clearly stated. Further, what about the Guile predicate? ✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝✝ Fr. Samuel, OSB (R. Padraic Springuel) St. Anselm’s Abbey 4501 South Dakota Ave, NE Washington, DC, 20017 202-269-2300 (c) 202-853-7036 PAX ☧ ΧΡΙΣΤΟΣ
