# Kunda


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## Install

``` sh
pip install kunda
```

## Select an interpreter

[`python_for`](https://vedicreader.github.io/kunda/pythons.html#python_for)
searches parent folders up to `stop`, then uses the supplied default or
a virtual environment under `roots`.
[`venv_env`](https://vedicreader.github.io/kunda/pythons.html#venv_env)
prepares the child’s environment.

``` python
selected = python_for(root/'src', stop=root)
choices = find_pythons(roots=[root], current=selected)
environment = venv_env(selected, env={'PATH': '/usr/bin'})
Path(selected).relative_to(root), [row['label'] for row in choices], environment['VIRTUAL_ENV']
```

    (Path('.venv/bin/python'),
     ['this one', 'tmps35syx1f/.venv', 'python3 on PATH', 'python on PATH'],
     '/private/var/folders/kg/9vdw4mdd1fs58svgh4k1qhr09x7dqh/T/tmps35syx1f/.venv')

## Run one kernel

Execution errors are returned in
[`ExecOutcome`](https://vedicreader.github.io/kunda/spec.html#execoutcome)
and leave the kernel available.

``` python
kernel = Kernel(cwd=root, inspect=True)
await kernel.start()
outcome = await kernel.execute('value = 21 * 2; value')
completion = await kernel.complete('val', 3)
outcome.ok, outcome.text, completion['matches'][:3]
```

    (True, '42', ['value'])

## Keep several kernels alive

Each key has at most one kernel.
[`RuntimeBroker`](https://vedicreader.github.io/kunda/pool.html#runtimebroker)
enforces a process-wide limit, and `idle=0` disables reaping.

``` python
class RustRunner: pass

broker = RuntimeBroker(max_kernels=12)
pool = KernelPool(broker=broker, idle=0,
                  runner_for=lambda lang: RustRunner if lang == 'rust' else None,
                  known_kernels={'julia': 'julia-1.10'})
broker.status(), pool._class_for({'lang': 'rust'}).__name__
```

    ({'live': 0, 'limit': 12, 'runtimes': []}, 'RustRunner')

## Kernel support

Support probes do not install packages. Installation uses the host’s
installed package versions.

``` python
support = kernel_support(python)
{k: v['available'] for k, v in support.items()}, installable(python)
```

    ({'ipykernel': False, 'ipymini': False}, True)

## Inspect live variables

With `inspect=True`, Kunda starts Dhrishti inside the kernel and reads
its registry.

``` python
await kernel.execute('visible_value = 42')
'name' in (await kernel.names()), 'visible_value' in (await kernel.names())
```

    (False, True)