REPL

The repl command starts an interactive FQL shell where you can type expressions and see results immediately.

$ferret repl

The shell prints a version banner and presents a > prompt:

Welcome to Ferret REPL v2.0.0-alpha.44
Please use `exit` or `Ctrl-D` to exit this program.
>

Evaluate expressions

Type any FQL expression at the prompt. The result prints as soon as evaluation finishes:

> return 1 + 2
3

> return { name: "Ada", active: true }
{"active":true,"name":"Ada"}

Multi-line input

For scripts that span multiple lines, start a block with %, type the lines, then close with % to submit:

> %
let users = [
    { name: "Ada", active: true },
    { name: "Grace", active: false }
]

return for user in users
    filter user.active
    return user.name
%
["Ada"]

Pass parameters

Use the --param flag to pass values into REPL queries. Parameters are accessible as @name:

$ferret repl --param greeting=hello

> return @greeting
"hello"

The --param flag follows the same format as the run command.

Runtime and browser flags

The REPL accepts the same runtime and browser flags as ferret run. For example, to start a REPL with a headless browser available:

$ferret repl --browser-headless

Exit

Type exit or press Ctrl-D to leave the REPL.

Next steps