⊢∘(f/) ⊢∘(f⌿) ⊢∘≢ ⊢∘⊂ {f/⍵} {f⌿⍵} {≢⍵} {⊂⍵} {⍺(≢⍵)}
⊂ ⊖ f⌿ f⍀ {⍵[⍋⍵]} {⍵[⍋⍵;]} {(⊂⍋⍵)⌷⍵}
↑ ↓ ≡ ≢ ⌿ ⍳
, ⍪ ⍉
(⍳∘1 ≥) (1 ∊ ≥) (∧/ ≥) (⍳ < (≢⊣))
f is a primitive scalar dyadic function.