BashScript
A JavaScript/TypeScript to bash transpiler. Work in progress.
Why? Mainly because I wanted to learn how to make a transpiler.
I also wanted to experiment with bash and how far we could stretch
this old, yet widely cross-platform language.
I've previously created a framework trying to make bash as usable as possible:
Bash Infinity.
This seemed like the natural next step.
Also, because... why not?
REPL
Not much works, but it's cool. :-)
Find it here: REPL.
Specification (WIP)
Function invocation
Function calls are transpilled as calls to bash functions/commands e.g.
input
echo('hi')output
echo hiif the call is used in the position of parameter or assignment: e.g.
input
const out = concat('hi', 'ho')output
declare out=$(concat 'hi' 'ho')Function declaration
input
function concat(a, b) {
return `${a}${b}`
}output
function concat {
local a="${1}"
local b="${2}"
echo "${a}${b}"
}Invoking properties
input
const a = 'abc'
const b = a.toLowercase()output
declare a='abc'
declare b="$(__callProperty a toLowercase)"Invoking properties with parameters
input
const arr = ['abc']
arr.push('xyz')output
declare arr=('abc')
__callProperty arr push 'xyz'Operators
input
const a = 'abc' + 'xyz'output
declare a="$(__operator_addition 'abc' 'zyx')"output helpers
# e.g.
__callProperty() {
if isArray arr
then
if property === 'push'
then
arr+=("${arr[@]}")
fi
fi
}Lambda functions
input
const concat = (a) => {
const c = `${a}-super`
return (b) => {
return `${c}${b}`
}
}
const withOne = concat('one')
const result = withOne('two')output
function concat {
# params:
local a="${1}"
# function body:
local c="${a}-super"
# preapplied function:
# lambda declaration is:
# [type, name, scoped_declarations_to_eval]
local -a declaration=(
function
__lambda_concat_1
"$(declare -p c)"
)
echo "$(declare -p declaration)"
}
# all functions are top level
function __lambda_concat_1 {
# scoped variables:
eval "${1}"; shift;
# actual function body:
local b="${1}"
echo "${c}${b}"
}
function __callVar {
# TODO: add check if var is a declaration
eval "${!1}"; shift;
if [[ "${declaration[1]}" == "function" ]]
then
"${declaration[1]}" "${declaration[2]}" "$@"
fi
}
declare withOne="$(concat 'one')"
declare result="$(__callVar withOne 'two')"Lambdas with scoped variables
input
const arr = [1, 2, 3]
const result = arr
.map(num => num + 1)
.map(num => num - 1)output
declare declaration=(1 2 3)
declare arr="$(declare -p declaration)"
unset declaration
__lamda_arr_map_anon_1() {
# scoped variables (if any):
eval "${1}"; shift;
# actual function body:
local num="${1}"
echo "$(__operator_addition num 1)"
}
__lamda_arr_map_anon_2() {
# scoped variables (if any):
eval "${1}"; shift;
# actual function body:
local num="${1}"
echo "$(__operator_substraction num 1)"
}
declare _result1="$(__callProperty arr map __lamda_arr_map_anon_1)"
declare result="$(__callProperty _result1 map __lamda_arr_map_anon_2)"
unset _result1Objects and other literals
input
const outerObject = {a: 'boom'}
const outerHello = 'hello from outer space!'
const obj = {
a: {
aa: 123,
bbb: {c: ['inner1', 'inner2', 'inner3']}
},
b: 'hello',
c: outerObject,
d: outerHello,
}
echo(obj.a.aa)output
#!/usr/bin/env bash
declare -A outerObject=(
[__type]=object
[a]="boom"
)
declare outerHello='hello from outer space!'
declare -a __obj_a_bbb_c=(inner1 inner2 inner3)
declare -A __obj_a_bbb=([ref_c]=__obj_a_bbb_c [__type]=object)
declare -A __obj_a=([aa]=123 [ref_bbb]="__obj_a_bbb" [__type]=object)
declare -A obj=(
[__type]=object
[ref_a]="__obj_a"
[b]="hello"
[ref_c]="outerObject"
# we need the TypeScript type to tell whether this is a reference or a plain object
[d]="${outerHello}"
)
# perhaps instead of using the ref_ prefix, we should use an uncommon prefix in the value
# that way we can reuse it for other reference-related functionality
@objectProperty() {
local objName="$1"
local property="$2"
shift
shift
local refName="${objName}[\"ref_${property}\"]"
local typeName="${objName}[\"__type\"]"
# we need to check type, because bash will return the value of first property if it doesn't exist on the object 🤦
if [[ -v "${refName}" && "${!typeName}" == 'object' ]]; then
local value="${!refName}"
if [[ "${#}" -gt 0 ]]; then
@objectProperty "${value}" "$@"
return
fi
echo "__ref:${value}"
else
refName="${objName}[${property}]"
if [[ -v "${refName}" ]]; then
if [[ "${#}" -gt 0 ]]; then
echo "Error: Cannot read property '${1}' of a non-object '${property}'."
return
fi
echo "${!refName}"
else
echo "Error: Cannot read property '${property}' of '${objName}'."
fi
fi
}
@objectProperty obj a aa