Tips

This page contains tips that users have suggested would have been useful to know when they first started with APL. It should be read in conjunction with Getting Started.

To suggest a tip or tell us something that you wish you'd known when you first started, send an email to tips@dyalog.com for consideration for inclusion on this page.

Getting Help

  • The ]Help user command opens the online documentation.
    • Entering ]Help followed by a symbol, user command, or I-beam. opens the online documentation page for it.
  • In the Microsoft Windows IDE or Ride, place the cursor on a symbol or other built-in and press F1 to open the online documentation page for it.
  • In the Microsoft Windows IDE or Ride, hover your mouse over a glyph in the language bar for a hint on how to type it and a quick overview of what it does.

Editing

  • Try the F1 tip above for )ED to learn how to quickly create new items of various types.
  • Use Shift + Enter to edit a name.
  • )ED "file:///path/file.ext" lets you edit plain-text files and, on closing the Session, asks you how to use the content.
  • Load APL functions/operators/objects from plain-text files with 2⎕FIX'file:///path/file.ext'.

Saving Your Work

... and picking up from where you left off.

  • If you enter )OFF then your Session log is saved before APL closes, so you can simply scroll up when you're ready to continue.
  • If you enter )CONTINUE then your workspace is saved with a temporary name and you can retrieve it with )LOAD continue.

Debugging and Meta Information

  • Use Ctrl + Enter to trace into a function and execute it one line at a time.
  • Use Shift + Enter with the cursor on white space to edit a suspended function.
  • Use Ctrl + Break to stop when an expression runs for a long time or results in long output in the session (alternatively, select Interrupt from the Session's Action menu).
  • Get all the technical details of the last error or event with ⎕JSON⍠'Compact'0⊢⎕DMX.
  • Enter 'tc'⎕CY'dfns' and then insert tc to the right of any function that you want to inspect

Shortcuts

  • Use Ctrl + Shift + Backspace and Ctrl + Shift + Enter to scroll backward and forwards through your input history (they can also be used as Undo and Redo in the Edit window.
  • Many in-built functionalities have neither menu items nor keyboard shortcuts assigned by default. To configure keyboard short-cuts, go to Options > Configure> Keyboard Shortcuts in the Microsoft Windows IDE or click the keyboard icon in Ride.
  • In the Microsoft Windows IDE, you can use the copy and paste buttons on the Object (not Edit) toolbar to copy and paste tables as matrices, documents as vectors of character vectors, and images as bitmap objects.

Display Forms

  • The settings in this section can be made permanent by saving your session:
    • In the Microsoft Windows IDE: Session > Save.
    • Within any Dyalog Session: 2⎕NQ⎕SE'FileWrite'.
  • ]Rows on -fold=3 will let you scroll horizontally and trim large outputs so that they don't flood your screen vertically.

Boxing

  • Turn boxing on to make the display of nested arrays more clear: 
          ]Box on
Was OFF
      ⍳2 3
┌───┬───┬───┐
│1 1│1 2│1 3│
├───┼───┼───┤
│2 1│2 2│2 3│
└───┴───┴───┘
  • With the trains modifier, you can display function trains with a tree structure: 
          ]Box -trains=tree
Was -trains=box
      +⌿÷≢
  ┌─┼─┐
  ⌿ ÷ ≢
┌─┘    
+
  • With the fns modifier, nested arrays will have boxed display even if they are printed to the session from within functions: 
          PrintShape←{⍴⎕←⍵}
      PrintShape ⍳1 3
 1 1  1 2  1 3 
1 3
      ]Box -fns=on
Was -fns=off
      PrintShape ⍳1 3
┌───┬───┬───┐
│1 1│1 2│1 3│
└───┴───┴───┘
1 3
  • With the style modifier you can get a more verbose view, including hints for axes and data types: 
          ]Box -style=max
┌→─────────────┐
│Was -style=min│
└──────────────┘
      ⊂'APL'
┌───────┐
│ ┌→──┐ │
│ │APL│ │
│ └───┘ │
└∊──────┘
  • See all the options with ]Box -??

Quick Utilities

  • ]Map displays the content and structure of your workspace.
  • ]Plot <data> draws simple graphs of your data (see ]Plot -?? for details).
  • ]Open <filename> opens a target file or internet address in its default application.
  • ]CD <dir> lets you change directory from inside an APL Session.
  • ]Get <source> lets you import data or code in many formats from local or remote sources.
  • In general, help for user commands can be found with ]<Command> -?.
  • Use ]Repr <myArray> to generate an expression for (almost) any given array.
  • Use the workspace explorer to see a tree view of your workspace:
    • In the Microsoft Windows IDE, go to Tools > Explorer.
    • In Ride (the default interface on macOS, optional interface on other platforms), go to View > Show Workspace Explorer.