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Table of Contents
APL-20 PANDAMONIUM REIGNS!
APLSF (System Function) is an implementation of the APL programming language for TOPS-20 that is available on TWENEX.
In and Out
To start the APL interpreter, type the following from EXEC:
@APLSF
At the terminal.. prompt, enter tty for a non-APL keyboard.
Leave APLSF by entering one of the following commands (APLSF converts all alphabetic input to upper-case):
)MON | Terminate APLSF and return to EXEC. |
)OFF | Terminate APLSF and log out of TWENEX. |
)CONTINUE | Save active workspace to file DSK:CONTIN.APL, terminate APLSF, log-out from TWENEX. The saved workspace will be loaded automatically the next time you run APLSF. |
To interrupt APLSF during execution, press Ctrl-C once or twice.
Press Ctrl-C five (5) times to suspend APLSF and return to EXEC. Resume APLSF with command @REENTER or @CONTINUE.
APL Character Set With ASCII and Escape Mode Equivalents
[For convenience, part of the keyboard mapping table from APLSF Language Manual is duplicated below.]
| APL Character | Name | ASCII | Escape Mode | APL Character | Name | ASCII | |
|---|---|---|---|---|---|---|---|
| ∧ | and | & | ⍒ | Grade Down | .GD | ||
| ← | assignment | _ | ⍋ | Grade Up | .GU | ||
| ÷ | divide | % | ⌶ | I-Beam (histogram) | .IB | ||
| ⋆ | exponentiate | * | @E | ⍟ | LoGarithm | .LG | |
| × | multiply | # | ⍲ | NaNd | .NN | ||
| ? | question (roll and deal) | ? | @Q | ⍱ | NoR | .NR | |
| ' | quote string | ' | @K | ⍀ | back expansion | .CB | |
| ↑ | take | ^ | @Y | ⊖ | (Circle) Rotate | .CR | |
| ∣ | residue (ABsolute value) | .AB | @M | ⌿ | back scan | .CS | |
| α | ALpha | .AL | @A | ⌹ | Divide Quad | .DQ | |
| ⎕ | quad (BoX) | .BX | @L | Input Quad | .IQ | ||
| ⌈ | CEiling (maximum) | .CE | @S | Output Quad | .OQ | ||
| ↓ | drop (Down Arrow) | .DA | @U | OUt | .OU | ||
| ¨ | Dieresis | .DD | ⍫ | Protected Del | .PD | ||
| ⊥ | DEcode | .DE | @B | Quad Del | .QD | ||
| ∇ | DeL | .DL | @G | ⍞ | Quad Quote | ||
| ◊ | DiaMond | .DM | ⌽ | ReVersal | .RV | ||
| ∩ | Down Under | .DU | @C | ⍉ | TRanspose | .TR | |
| ⊤ | ENcode | .EN | @N | ⍎ | eXecute | .XQ | |
| ∈ | EPsilon | .EP | @E | ⍕ | ForMat | .FM | |
| ⌊ | FLoor | .FL | @D | ⍝ | Comment (lamp) | “ | |
| ≥ | Greater then or Equal to | .GE | A-Z | underscored alphabetics | .ZA-.ZZ | ||
| → | GO to (branch) | .GO | ⍙ | underscored lower del | .Z@ | ||
| ⍳ | IOta | .IO | @I | ||||
| { | Left curly Brace | .LB | |||||
| ∆ | delta (Lower Del) | .LD | @H | ||||
| ≤ | Less than or Equal to | .LE | |||||
| ⊢ | Left tacK | .LK | |||||
| ○ | circle (Large O) | .LO | @O | ||||
| ⊃ | Left Union | .LU | @X | ||||
| ≠ | Not Equal to | .NE | |||||
| − | NeGation | .NG | |||||
| ∼ | NoT | .NT | @T | ||||
| ⍵ | OMega | .OM | @W | ||||
| ∨ | OR | .OR | |||||
| } | Right curly Brace | .RB | |||||
| ⍴ | RhO | .RO | @R | ||||
| ⊣ | Right tacK | .RK | |||||
| ⊂ | Right Union | .RU | @Z | ||||
| ∘ | jot (Small O) | .SO | @J | ||||
| _ | UnderScore | .US | @F | ||||
| ∪ | Up Union | .UU | @V |
Function Editor
To define a new function and invoke the editor, enter one of the following commands:
.DL[r_]a1 f a2[;v]… | Define a dyadic (two-argument) function |
.DL[r_]f a1[;v]… | Define a monadic (one-argument) function |
.DL[r_]f[;v]… | Define a niladic (no-argument) function |
Where:
| f | Function name |
| a1, a2 | Dummy arguments |
| r | Dummy variable for return value |
| v | Local variable |
To edit an existing function, enter the command .DLf.
The editor will start and prompt with the current line number, for example [1].
Editor commands
text | Add text at current line. |
[n]text | Replace line n with text. Edit the function header as line 0. |
[n.m]text | Insert text as new line after line n. |
[.LDn] | Delete line n. |
[.BX] | List function source. |
[n.BX] | List line n. |
[.BXn] | List from line n to the end of the function. |
.DL | Save function and return from editor. |
Multiple commands can be entered on a single line. For an example, you can open the editor on existing function F, list its source, and immediately exit the editor by entering the following command in the APL interpreter:
.DLF[.BX].DL
References
- APLSF Language Manual. Digital Equipment Corporation, 1979.
- APL\1130 Primer. International Business Machines Corporation, 1968.
