| The Fine Print
 The expressions require Dyalog APL
[136]
version 14.0 or later, with: 
| ⎕io←0 | index origin |  | ⎕ml←1 | migration level |  | ⎕pp←6 | print precision |  | ⎕div←1 | the result of 0÷0 is 0 |  | ]box on | nested arrays displayed using boxes |  |  |  | assert←{⍺←'assertion failure' ⋄ 0∊⍵:⍺ ⎕signal 8 ⋄ shy←0} |  |  | a utility
[124b] |  Some expressions use facilities not yet implemented as of this writing
(and may never be implemented in Dyalog APL).
They are: 
| x⍸y | interval index
[52],
sorted x partitions the domain into contiguous intervals
and x⍸y is the index of the interval that contain y |  | ⍸x | where
[52], 
{(,⍵)/,⍳⍴⍵} , indices of where boolean array x is 1 |  | ⊤x | binary representation
[100], 
 2⊥⍣¯1⊢x |  | ⊥x | binary value
[100], 
 2⊥x |  | ∞ | infinity
[123,
124a] |  | ⍭ | primes, ⍭i is the i-th prime, modeled by pco in the dfns workspace
 [89] |  | ⍢ | under
[51h], | 
 |  | f⍢g x   ←→ g⍣¯1 f g x |  |  | x f⍢g y ←→ g⍣¯1 (g x)f(g y) |  |  | ⍫ | obverse [51i], 
 f⍫g ←→ f except that f⍫g⍣¯1 ←→ g⍫f |  
 |