JPL

Fixed point scan

{⍵÷2} ⍣ ⍬ ⊢ 55

Power scan with condition

{⍵÷2} ⍣ {⍵≥1} ⍣ ⍬ ⊢ 10

Amend

1 (<1 1) ⊙ 3 3⍴0

Stencil (no padding)

2 2 < ⌺ ¯3 ⊢ 3 3⍴0

Counts

(↑,≢) ⌸⍨ 1 2 1 2 1

Inverse/obverse

str ← '24:00'

split ← chopstring
join ← {(⍕0⌷⍵),⍺,(⍕1⌷⍵)}

serde ← ((60∘⊥) ⍤ ((⍎¨)⇔(⍕¨)) ⍤ ((':'∘split)⇔(':'∘join)))

3 {÷∘⍺⍢serde⍵} str