mario 0.0.104

Shell pipes for Python.

mario: command-line pipes in Python

Your favorite plumbing snake 🐍🔧 with your favorite pipes, right in your shell 🐢.

Usage

Basics

Invoke with mario at the command line.

$ mario eval 1+1
2

Use map to act on each item in the file with python commands:

$ mario map x.upper() <<<'abc'
ABC

Chain python functions together with !:

$ mario map 'x.upper() ! len(x)' <<<hello
5

or by adding another command

$ mario map 'x.upper()' map 'len(x)' <<<hello
5

Use x as a placeholder for the input at each stage:

$ mario map ' x.split()[0] ! x.upper() + "!"' <<<'Hello world'
HELLO!

$ mario map 'x.split()[0] ! x.upper() + "!" ! x.replace("H", "J")' <<<'Hello world'
JELLO!

Automatically import modules you need:

$ mario stack 'itertools.repeat(x, 2) ! "".join' <<<hello,world!
hello,world!
hello,world!

Commands

eval

Use eval to evaluate a Python expression.

$ mario eval 'datetime.datetime.utcnow()'
2019-01-01 01:23:45.562736

map

Use map to act on each input item.

$ mario map 'x * 2' <<<'a\nbb\n'
aa
bbbb

filter

Use filter to evaluate a condition on each line of input and exclude false values.

$  mario filter 'len(x) > 1' <<<'a\nbb\nccc\n'
bb
ccc

apply

Use apply to act on the sequence of items.

$   mario apply 'len(x)' <<<'a\nbb\n'
2

stack

Use stack to treat the input as a single string, including newlines.

$  mario stack 'len(x)' <<<'a\nbb\n'
5

reduce

Use reduce to evaluate a function of two arguments successively over a sequence, like functools.reduce.

For example, to multiply all the values together, first convert each value to int with map, then use reduce to successively multiply each item with the product.

$ mario map int reduce operator.mul <<EOF
1
2
3
4
EOF

24

Autocall

You don’t need to explicitly call the function with f(x); just use f. For example, instead of

$ mario map 'len(x)' <<<'a\nbb'
5

try

$ mario map len <<<'a\nbb'
5

Async

Making sequential requests is slow. These requests take 20 seconds to complete.

$ time mario map 'requests.get ! x.text ! len' apply max <<EOF
http://httpbin.org/delay/5
http://httpbin.org/delay/1
http://httpbin.org/delay/4
http://httpbin.org/delay/3
http://httpbin.org/delay/4
EOF

302

0.61s user
0.06s system
19.612 total

Concurrent requests can go much faster. The same requests now take only 6 seconds. Use amap, or afilter, or reduce with await some_async_function to get concurrency out of the box.

$ time mario amap 'await asks.get ! x.text ! len' apply max <<EOF
http://httpbin.org/delay/5
http://httpbin.org/delay/1
http://httpbin.org/delay/4
http://httpbin.org/delay/3
http://httpbin.org/delay/4
EOF

297

0.57s user
0.08s system
5.897 total

Async streaming

amap and afilter values are handled in streaming fashion, while retaining the order of the input items in the output. The order of function calls is not constrained – if you need the function to be called with items in a specific order, use the synchronous version.

Making concurrent requests, each response is printed one at a time, as soon as (1) it is ready and (2) all of the preceding requests have already been handled.

For example, the 3 seconds item is ready before the preceding 4 seconds item, but it is held until the 4 seconds is ready because 4 seconds was started first, so the ordering of the input items is maintained in the output.

$ time mario --exec-before 'import datetime; now=datetime.datetime.utcnow; START_TIME=now(); print("Elapsed time | Response size")' map 'await asks.get !  f"{(now() - START_TIME).seconds} seconds    | {len(x.content)} bytes"'  <<EOF
http://httpbin.org/delay/1
http://httpbin.org/delay/2
http://httpbin.org/delay/4
http://httpbin.org/delay/3
EOF
Elapsed time | Response size
1 seconds    | 297 bytes
2 seconds    | 297 bytes
4 seconds    | 297 bytes
3 seconds    | 297 bytes

Configuration

Add code to automatically execute, into your config file.

For example:

# ~/.config/mario/config.toml

base_exec_before = """

from itertools import *
from collections import Counter

"""

Then you can directly use the imported objects without referencing the module.

$ mario map 'Counter ! json.dumps' <<<'hello\nworld\n'
{"h": 1, "e": 1, "l": 2, "o": 1}
{"w": 1, "o": 1, "r": 1, "l": 1, "d": 1}

You can set any of the mario options in your config. For example, to set a different default value for the concurrency maximum mario --max-concurrent, add max_concurrent to your config file (note the underscore):

# ~/.config/mario/config.toml

max_concurrent = 10

then just use mario as normal.

Aliases

Define new commands in your config file which provide aliases to other commands. For example, this config adds a jsonl command for reading jsonlines streams into Python objects, by calling calling out to the map traversal.

[[alias]]

name = "jsonl"
short_help = "Load jsonlines into python objects."

[[alias.stage]]

command = "map"
options = []
arguments = [ "json.loads ! types.SimpleNameSpace(**x)" ]

Now we can use it like a regular command:

$ mario jsonl  <<< $'{"a":1, "b":2}\n{"a": 5, "b":9}'
X(a=1, b=2)
X(a=5, b=9)

The new command jsonl can be used in pipelines as well. To get the maximum value in a sequence of jsonlines objects:

$ mario jsonl map 'x.a' apply max <<< $'{"a":1, "b":2}\n{"a": 5, "b":9}'
5

Plugins

Add new commands like map and reduce by installing mario plugins. You can try them out without installing by adding them to any .py file in your ~/.config/mario/modules/.

Installation

Get it with pip:

python3.7 -m pip install mario

Caveats

• mario assumes trusted command arguments and untrusted input stream data. It uses eval on your commands, not on the input stream data. If you use exec, eval, subprocess, or similar commands, you can execute arbitrary code from the input stream, like in regular python.

Status

• Check the issues page for open tickets.

• This package is experimental and is subject to change without notice.

Related work

A number of cool projects have pioneered in the Python-in-shell space.

• https://github.com/Russell91/pythonpy

• http://gfxmonk.net/dist/doc/piep/

• https://spy.readthedocs.io/en/latest/intro.html

• https://github.com/ksamuel/Pyped

• https://github.com/ircflagship2/pype