# Read-eval-print-loop

`deno repl` starts an read-eval-print-loop, which lets you interactively build
up program state in the global context.

## Keyboard shortcuts

| Keystroke             | Action                                                                                           |
| --------------------- | ------------------------------------------------------------------------------------------------ |
| Ctrl-A, Home          | Move cursor to the beginning of line                                                             |
| Ctrl-B, Left          | Move cursor one character left                                                                   |
| Ctrl-C                | Interrupt and cancel the current edit                                                            |
| Ctrl-D                | If if line _is_ empty, signal end of line                                                        |
| Ctrl-D, Del           | If line is _not_ empty, delete character under cursor                                            |
| Ctrl-E, End           | Move cursor to end of line                                                                       |
| Ctrl-F, Right         | Move cursor one character right                                                                  |
| Ctrl-H, Backspace     | Delete character before cursor                                                                   |
| Ctrl-I, Tab           | Next completion                                                                                  |
| Ctrl-J, Ctrl-M, Enter | Finish the line entry                                                                            |
| Ctrl-K                | Delete from cursor to end of line                                                                |
| Ctrl-L                | Clear screen                                                                                     |
| Ctrl-N, Down          | Next match from history                                                                          |
| Ctrl-P, Up            | Previous match from history                                                                      |
| Ctrl-R                | Reverse Search history (Ctrl-S forward, Ctrl-G cancel)                                           |
| Ctrl-T                | Transpose previous character with current character                                              |
| Ctrl-U                | Delete from start of line to cursor                                                              |
| Ctrl-V                | Insert any special character without performing its associated action (#65)                      |
| Ctrl-W                | Delete word leading up to cursor (using white space as a word boundary)                          |
| Ctrl-X Ctrl-U         | Undo                                                                                             |
| Ctrl-Y                | Paste from Yank buffer                                                                           |
| Ctrl-Y                | Paste from Yank buffer (Meta-Y to paste next yank instead)                                       |
| Ctrl-Z                | Suspend (Unix only)                                                                              |
| Ctrl-_                | Undo                                                                                             |
| Meta-0, 1, ..., -     | Specify the digit to the argument. `–` starts a negative argument.                               |
| Meta-<                | Move to first entry in history                                                                   |
| Meta->                | Move to last entry in history                                                                    |
| Meta-B, Alt-Left      | Move cursor to previous word                                                                     |
| Meta-Backspace        | Kill from the start of the current word, or, if between words, to the start of the previous word |
| Meta-C                | Capitalize the current word                                                                      |
| Meta-D                | Delete forwards one word                                                                         |
| Meta-F, Alt-Right     | Move cursor to next word                                                                         |
| Meta-L                | Lower-case the next word                                                                         |
| Meta-T                | Transpose words                                                                                  |
| Meta-U                | Upper-case the next word                                                                         |
| Meta-Y                | See Ctrl-Y                                                                                       |

## Special variables

| Identifier | Description                          |
| ---------- | ------------------------------------ |
| _          | Yields the last evaluated expression |
| _error     | Yields the last thrown error         |