Shells and interpreters

Weave expressions

A weave expression embeds a foreign script within a BushelScript program. When a weave is evaluated, its body is evaluated by the shell or other interpreter specified in its hashbang (#!) line.

Another #! on its own line ends the weave body. If it declares an interpreter, it also begins a new weave.

#!/bin/bash

echo 'Hello, world!'

#!/usr/bin/python3

print(input())

#!

alert that

This example uses two weave expressions, one using Bash and another using Python.

Weave output

Weave expressions evaluate to whatever is written to their standard output. In the above example, the Bash script writes Hello, world! to its stdout, causing the bash weave to evaluate to the string value "Hello, world!".

Weave input

Similarly, weaves are automatically provided, through standard input, the current value of that coerced to a string. In the above example, the Python script reads the result of the bash weave from its own stdin and echoes it back out.