LAMBDA idea: ALPHABET

[jimmytacks]

Origin

Synced from Notion: LAMBDA: ALPHABET

Problem

The library has no stored letter constants. Letter-based puzzles — index↔letter, Scrabble/cipher scoring, vowel/consonant counts, "Nth letter" — need the alphabet, vowels, or consonants instantly. Deriving consonants (alphabet minus vowels) from scratch under a 30-minute clock wastes time. The competitor stored six bare constants (_alphabet_l/u, _vowels_l/u, _consonants_l/u); we prefer one parametrised function for discoverability.

Proposed

=ALPHABET([case], [subset])

• case — "U" uppercase (default) / "L" lowercase
• subset — "ALL" (default) / "VOWELS" / "CONSONANTS"

Returns a spilled array of the requested letters (26 / 5 / 21).

Examples

• =ALPHABET() → A, B, C, … , Z
• =ALPHABET("L", "VOWELS") → a, e, i, o, u
• =XMATCH("M", ALPHABET()) → 13 (letter → index)

Notes

• One discoverable name instead of six bare constants (fits the "fewer public names" preference).
• alphabet itself is trivially CHAR(SEQUENCE(26,,65)); vowels / consonants are the parts that actually earn storing.
• Pairs with existing EXPLODE / CHARQ for letter-indexing work.