Build a Powerful Python REPL in Under 20 Lines with Prompt Toolkit, Click, and More

Python Prompt Toolkit

Install the library:

pip install prompt_toolkit

Basic Interactive Interpreter

A minimal REPL that echoes user input:

from prompt_toolkit import prompt
while 1:
    user_input = prompt('> ')
    print(user_input)

History Support

Persist command history using FileHistory:

from prompt_toolkit import prompt
from prompt_toolkit.history import FileHistory
history = FileHistory('history.txt')
while 1:
    user_input = prompt('>', history=history)
    print(user_input)

Auto‑Suggest from History

Add fish‑style suggestions based on previous commands:

from prompt_toolkit import prompt
from prompt_toolkit.history import FileHistory
from prompt_toolkit.auto_suggest import AutoSuggestFromHistory
history = FileHistory('history.txt')
while 1:
    user_input = prompt('>', history=history, auto_suggest=AutoSuggestFromHistory())
    print(user_input)

Auto‑Completion

Use WordCompleter to provide tab‑completion for SQL keywords:

from prompt_toolkit import prompt
from prompt_toolkit.completion import WordCompleter
SQLCompleter = WordCompleter(['select','from','insert','update','delete','drop'], ignore_case=True)
while 1:
    user_input = prompt('SQL>', completer=SQLCompleter)
    print(user_input)

Click – Command‑Line Interface Toolkit

Install Click: pip install click Use Click’s pager to display long output:

import click
click.echo_via_pager(user_input)

Launch an editor and capture its content:

import click
message = click.edit()

Fuzzy Search

Install fuzzyfinder and use it to suggest completions based on partial input:

pip install fuzzyfinder
from fuzzyfinder import fuzzyfinder
suggestions = fuzzyfinder('abc', ['abcd','defabca','aagbec','xyz','qux'])
list(suggestions)

Pygments – Syntax Highlighting

Install Pygments and apply the SQL lexer to colourise user input:

pip install pygments
from pygments.lexers import SqlLexer
# Pass SqlLexer to Prompt Toolkit’s lexer argument (omitted for brevity)

Conclusion

By combining Prompt Toolkit, Click, fuzzyfinder and Pygments you can build a full‑featured REPL that offers history navigation, key bindings, intelligent auto‑completion, fuzzy search, paging, editor integration and colourful syntax highlighting—all with fewer than twenty lines of Python code.