filo-repl

README

filo-repl

Interactive REPL (Read-Evaluate-Print Loop) for the Filo language.

Features

• Interactive mode: Line editing, command history, multi-line input
• Batch mode: Pipe-friendly execution when stdin is not a TTY
• Multi-line expressions: Automatically continues reading until parentheses are balanced
• Editor integration: :edit opens $EDITOR to edit complex expressions
• Extension packages: Load math, rand, or string builtins

Building

go build -o filo-repl ./cmd/filo-repl

Usage

Interactive REPL

./filo-repl

You'll see:

Filo REPL - Type expressions to evaluate. Ctrl+D to exit.

filo> (+ 1 2)
3
filo> (if (> 10 5)
...     "yes"
...     "no")
yes
filo>

Batch Mode (Pipes)

echo '(+ 1 2 3)' | ./filo-repl
# Output: 6

cat script.filo | ./filo-repl --filo-package math

With Extension Packages

# Math functions
./filo-repl --filo-package math
filo> (sqrt 16)
4

# String functions
./filo-repl --filo-package str
filo> (str-upper "hello")
HELLO

# Multiple packages
./filo-repl --filo-package math,str,rand

REPL Commands

Command	Description
.help	Show help in pager ($PAGER or less)
.edit	Open $EDITOR to edit input
.clear	Clear current input buffer
.quit	Exit REPL (also: .exit, .q)

Keyboard Shortcuts

Key	Action
Enter	Execute if balanced, continue if not
Ctrl+D	Exit (empty) or force execute (with content)
Up/Down	Navigate command history

Flags

Flag	Default	Description
--filo-package	(none)	Comma-separated: math, rand, str
--step-limit	100000	Maximum evaluation steps
--recursion-limit	128	Maximum recursion depth
--timeout	30	Timeout in seconds

Extension Packages

Package	Description
math	sqrt, sin, cos, log, abs, floor, ceil, round, etc.
rand	rand-float, rand-int, uuid-v4
str	str-upper, str-lower, str-trim, str-split, str-join, etc.

Exit Codes

Code	Meaning
0	Success
1	Error

Documentation

Overview

Command filo-repl provides an interactive REPL for the Filo language.

When stdin is a TTY, it runs in interactive mode with line editing, history, and multi-line support. When stdin is a pipe, it runs in batch mode.

Usage:

filo-repl                         # Interactive REPL
echo '(+ 1 2)' | filo-repl        # Batch mode
filo-repl --filo-package math     # REPL with math package