Typing APL symbols

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APL uses a large range of special graphic symbols to represent most functions and operators. While keyboard mappings become memorized over time, entering APL characters can frustrate the beginner. However, a study involving high school students found that typing and using APL characters did not hinder the students in any measurable way. There are several convenient ways to enter the glyphs.

Keyboard mappings

Most of today's APLs use a mapping which derives from the original APL\360 terminals' keyboard layout. For example, Dyalog APL's standard US English layout for is as follows:

┌────┬────┬────┬────┬────┬────┬────┬────┬────┬────┬────┬────┬────┬─────────┐
│~ ⌺ │! ⌶ │@ ⍫ │# ⍒ │$ ⍋ │% ⌽ │^ ⍉ │& ⊖ │* ⍟ │( ⍱ │) ⍲ │_ ! │+ ⌹ │Backspace│
│` ⋄ │1 ¨ │2 ¯ │3 < │4 ≤ │5 = │6 ≥ │7 > │8 ≠ │9 ∨ │0 ∧ │- × │= ÷ │         │
├────┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──┬──────┤
│Tab    │Q   │W   │E ⍷ │R   │T ⍨ │Y   │U   │I ⍸ │O ⍥ │P ⍣ │{ ⍞ │} ⍬ │| ⊣   │
│       │q ? │w ⍵ │e ∊ │r ⍴ │t ~ │y ↑ │u ↓ │i ⍳ │o ○ │p * │[ ← │] → │\ ⊢   │
├───────┴┬───┴┬───┴┬───┴┬───┴┬───┴┬───┴┬───┴┬───┴┬───┴┬───┴┬───┴┬───┴──────┤
│Caps    │A   │S   │D   │F   │G   │H   │J ⍤ │K ⌸ │L ⌷ │: ≡ │" ≢ │Enter     │
│Lock    │a ⍺ │s ⌈ │d ⌊ │f _ │g ∇ │h ∆ │j ∘ │k ' │l ⎕ │; ⍎ │' ⍕ │          │
├────────┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──┬─┴──────────┤
│Shift      │Z ⊆ │X   │C   │V   │B   │N   │M   │< ⍪ │> ⍙ │? ⍠ │Shift       │
│           │z ⊂ │x ⊃ │c ∩ │v ∪ │b ⊥ │n ⊤ │m | │, ⍝ │. ⍀ │/ ⌿ │            │
└───────────┴────┴────┴────┴────┴────┴────┴────┴────┴────┴────┴────────────┘

Additional charts for other layouts are available.

There are multiple was to access the glyphs associated with a particular key.

Shifting key

It is quite common to use Ctrl or Alt or AltGr (right-side Alt) as an additional shifting key. For example, AltGr+AltGr+4 would give while AltGr+Shift+4 would give .

  • APLX uses AltGr with an option to also use Alt

Prefix key

A prefix key is a special key or character which is entered immediately before typing the corresponding key.

  • TryAPL and ngn/apl's scripted demo interface support ` as prefix key.
  • The Dyalog Unicode IME and the Dyalog RIDE (Remote Integrated Development Environment) uses ` by default, but allows choosing any key as prefix key.
US keyboard with Dyalog APL glyphs

Hardware APL keyboard

A couple of hardware keyboards are being sold with APL symbols pre-printed onto the key caps:

Keyword look-up

  • The Dyalog RIDE (Remote Integrated Development Environment) allows hitting the prefix key (` by default, but configurable) twice, followed by the (beginning of the) name of a symbol or a functionality. It then displays a drop-down of choices with arrow keys to indicate choice and the Tab key to insert the symbol. E.g. `,`,d,i,v,Tab↹ inserts ÷.

ASCII symbol combination

  • Many APL glyphs can be approximated by overlaying or juxtaposing two ASCII characters. ngn/apl's scripted demo interface and Adám Brudzewsky's in-browser language bar allow such a pair of characters and hitting the Tab key to replace them with the corresponding APL character. For example, <,-,Tab↹ will insert and T,o,Tab↹ will insert .

On-screen language bar

Several APL IDEs allow the display of a toolbar with a button for each APL glyph:

Web browsers


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