YAMLScript

We use YAML syntax to define a set of tasks declaratively, YAMLScript will help you compile it into Javascript code that runs on Deno. Think about Lisp, but in YAML.

Note You need to know the basic syntax of YAML, javascript, and maybe a little Deno, if you havn’t, check outLearn YAML in Y minutes and Learn Javascript in Y minutes, it’s not hard!

Warning This project is still in a very early stage, the api may consider changes.

YAMLScript is designed to solve the most common problems with minimal knowledge. It can be considered as an alternative for dotfiles utilities such as chezmoi, or an alternative to automated workflows such as Ansible, it can also be a low-code alternative to IFTTT, Zapier, Pipedream, etc.

Run task file directly:

ys run task.ys.yml

Build task file and deploy the compiled code to serverless services such as Deno Deploy:

ys build task.ys.yml && deployctl deploy --project=helloworld ./dist/task.js

In YAMLScript, The following interface is the only property we need to understand, they are all optional.

interface Task {
  id?: string;
  name?: string;
  from?: string;
  use?: string;
  args?: unknown | unknown[];
  loop?: string | number | unknown[];
  if?: boolean | string;
  throw?: boolean;
}

And the compiled Javascript code is human readable, so if anything goes wrong, we can easily locate and fix it. If you run into problems, go to the compiled Javascript code, which is located in the dist directory by default.

Simple Usage

Basic

# We use `def` to define a new variable
# `id` will be the variable name, `args` will be the value
- use: def
  id: obj
  args:
    list:
      - Hello
      - true
    foo:
      cat: 10

# We use javascript template string ${expression} for string interpolation
# You can use any valid js template expression here, even function.
# ${} can be escaped as \${} if needed
- use: console.log
  args:
    - ${obj.list[0]} World
    - ${obj.foo.cat}
    - ${JSON.stringify(obj.foo)}

This will be compiled to:

let result = null;

// Task #0: obj
let obj = {
  "list": [
    `Hello`,
    true
  ],
  "foo": {
    "cat" : 10
  }
};

// Task #1
result = await console.log(`${obj.list[0]} World`,`${obj.foo.cat}`,`${JSON.stringify(obj.foo)}`);

Use

# `use` is the operator name of the a task.
# We can use any Deno runtime function here
- use: fetch
  args: https://jsonplaceholder.typicode.com/todos/1

# We also have some built-in functions, e.g., fetch rss feed entries

- use: rss.entries
  args: https://actionsflow.github.io/test-page/hn-rss.xml

# We also have a built-in lodash
# All built-in functions can be found here:
# https://github.com/yamlscript/yamlscript/blob/main/globals/mod.ts

# this will print: [2, 1]
- use: _.uniq
  args: [2, 1, 2]

# use alias?

- from: https://deno.land/std@0.149.0/path/mod.ts
  use: extname as getExt
  args: test.js
- use: assertEquals
  args:
    - .js
    - $result

# use instance?

- use: new URL
  args: http://www.example.com/dogs
- use: assertEquals
  args:
    - www.example.com
    - $result.hostname

This will be compiled to:

import { rss } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
import { _ } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
import { extname as getExt } from "https://deno.land/std@0.149.0/path/mod.ts";
import { assertEquals } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
let result = null;

// Task #0
result = await fetch(`https://jsonplaceholder.typicode.com/todos/1`);

// Task #1
result = await rss.entries(`https://actionsflow.github.io/test-page/hn-rss.xml`);

// Task #2
result = await _.uniq(2,1,2);

// Task #3
result = await getExt(`test.js`);

// Task #4
result = await assertEquals(`.js`,result);

// Task #5
result = await new URL(`http://www.example.com/dogs`);

// Task #6
result = await assertEquals(`www.example.com`,result.hostname);

Args

# `args` can be array or other type
# if it's not an array, will be the first argument for the task
- use: rss.entries
  args: https://actionsflow.github.io/test-page/hn-rss.xml

# You can visit https://requestbin.com/r/enyvb91j5zjv9/23eNPamD4DK4YK1rfEB1FAQOKIj
# to check the http request.
- use: fetch
  args:
    - https://enyvb91j5zjv9.x.pipedream.net/
    - method: POST
      headers:
        Content-Type: application/json
      body: |
        {
          "title": "Hello world"
        }

This will be compiled to:

import { rss } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
let result = null;

// Task #0
result = await rss.entries(`https://actionsflow.github.io/test-page/hn-rss.xml`);

// Task #1
result = await fetch(`https://enyvb91j5zjv9.x.pipedream.net/`,{
  "method" : `POST`,
  "headers": {
    "Content-Type" : `application/json`
  },
  "body" : `{
    "title": "Hello world"
  }
  `
});

Result

- use: Math.max
  args: [1, 9, 5]

# We use `result` to indicate the return result of the previous task
# This will print "9"
- use: console.log
  args: ${result}

# How to print number 9?
# use `$expression`
# $expression can be escaped as \$expression if needed
- use: console.log
  args: $result

# We can also use `id` to define a identifier of the task
- id: max
  use: Math.max
  args: [1, 9, 5]

# then we can use the $id to represent the task result.
- use: console.log
  args:
    - $max

This will be compiled to:

let result = null;

// Task #0
result = await Math.max(1,9,5);

// Task #1
result = await console.log(`${result}`);

// Task #2
result = await console.log(result);

// Task #3: max
result = await Math.max(1,9,5);
const max = result;

// Task #4
result = await console.log(max);

If

# We can use `if` to control structures
# args is an built-in function, return the args
- use: def
  id: num
  args: 5

# You can use any js expression here, you may omit the expression syntax `$`
# Cause we evaluates the if conditional as an expression.
# this will print: yes, the args is greater than 4
- if: num > 4
  use: console.log
  args: yes, the args is greater than 4

- if: true
  use: console.log
  args: yes, it's true

This will be compiled to:

let result = null;

// Task #0: num
let num = 5;

// Task #1
if (num > 4) {
  result = await console.log(`yes, the args is greater than 4`);
}

// Task #2
result = await console.log(`yes, it's true`);

Loop

# We use `loop` to define a loop, it can be an literal array
# You can access the item by using `item`
# the index by using `index`

# This will print "1. foo\n2. bar"
- loop:
    - foo
    - bar
  use: console.log
  args: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mrow><mi>i</mi><mi>n</mi><mi>d</mi><mi>e</mi><mi>x</mi></mrow><mi mathvariant="normal">.</mi></mrow><annotation encoding="application/x-tex">{index}. </annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.6944em;"></span><span class="mord"><span class="mord mathnormal">in</span><span class="mord mathnormal">d</span><span class="mord mathnormal">e</span><span class="mord mathnormal">x</span></span><span class="mord">.</span></span></span></span>{item}

- id: sources
  use: def
  args:
    - - 1
      - 2
# use $sources to get literals result

- id: loopResults
  loop: $sources
  use: _.multiply
  args:
    - $item
    - 2
# loopResults will be an array, every result of the loop will be pushed.

This will be compiled to:

import { _ } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
let index = 0;
let result = null;

// Task #0
{
  const item = `foo`;
  index = 0;
  result = await console.log(`${index}. ${item}`);
}
{
  const item = `bar`;
  index = 1;
  result = await console.log(`${index}. ${item}`);
}
index = 0;

// Task #1: sources
let sources = [
  1,
  2
];

// Task #2: loopResults
let loopResults = [];
for await (const item of sources){
  result = await _.multiply(item,2);
  loopResults.push(result);
  index++;
}
index=0;

Function

# We also support define a function by using `defn`
# args[0] is the first argument, args[1] is the second argument.
- use: defn
  id: myFunction
  args:
    - use: _.upperCase
      args: $args[0]

# Then we can use this function
- use: myFunction
  args: abc

# assertEquals is a built-in function to do some tests
# which is from Deno std
# https://deno.land/std@0.149.0/testing#usage
- use: assertEquals
  args:
    - $result
    - ABC

This will be compiled to:

import { _ } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
import { assertEquals } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
let result = null;

// Task #0: myFunction
async function myFunction(...args){

  // Task #0_0
  result = await _.upperCase(args[0]);

  return result;
}

// Task #1
result = await myFunction(`abc`);

// Task #2
result = await assertEquals(result,`ABC`);

Shell

# We use colon plus cmd to run a command
- id: echo
  use: :echo Hello World

# Result will be:
# {
#   stdout: "Hello World\n",
#   stderr: "",
#   combined: "Hello World\n",
#   status: { success: true, code: 0 },
#   retries: 0
# }

- use: assertEquals
  args:
    - $echo.stdout
    - "Hello World\n"

This will be compiled to:

import { __yamlscript_create_process } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/runtimes/cmd/mod.ts";
import { assertEquals } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
let result = null;

// Task #0: echo
const __yamlscript_default_use_0 =  __yamlscript_create_process();
result = await __yamlscript_default_use_0`echo Hello World`;
const echo = result;

// Task #1
result = await assertEquals(echo.stdout,`Hello World
`);

Advanced Usage

1 Prevent Throw Error

# Sometimes we want to ignore error, and let the tasks continue on error
# we use throw: false to prevent YAMLScript throw an error.
# when using throw: false, the result will be an object
# {
#  value: unknown
#  done: boolean
# }
# when task is failed, the value will be the error
# when task is success, the value will be the function result.
- use: JSON.parse
  args: "foo?bar"
  throw: false
  id: errorExample
- use: assertEquals
  args:
    - $errorExample.done
    - false
- use: assertEquals
  args:
    - $errorExample.value.message
    - Unexpected token 'o', "foo?bar" is not valid JSON

This will be compiled to:

import { assertEquals } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
let result = null;

// Task #0: errorExample
let errorExample;
try {
  result = await JSON.parse(`foo?bar`);
  errorExample = result;
  result = {
    value: result,
    done: true
  };
  errorExample = result;
} catch (error) {
  result = {
    value: error,
    done: false
  };
  errorExample = result;
}

// Task #1
result = await assertEquals(errorExample.done,false);

// Task #2
result = await assertEquals(errorExample.value.message,`Unexpected token 'o', "foo?bar" is not valid JSON`);

2 New Instance

# How to create class instance?
# just use new functioname
- use: new Date
  args: 2022-07-25
- use: assertEquals
  args:
    - "1658707200000"
    - ${result.getTime()}

This will be compiled to:

import { assertEquals } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
let result = null;

// Task #0
result = await new Date(`2022-07-25T00:00:00.000Z`
);

// Task #1
result = await assertEquals(`1658707200000`,`${result.getTime()}`);

Return

# Use `return` to end the function
- use: defn
  id: myFunction
  args:
    - use: console.log
      args: foo
    - use: return
      if: true
    - use: console.log
      args: this will not be printed
- use: myFunction

This will be compiled to:

let result = null;

// Task #0: myFunction
async function myFunction(...args){

  // Task #0_0
  result = await console.log(`foo`);

  // Task #0_1
  return;

  // Task #0_2
  result = await console.log(`this will not be printed`);

  return result;
}

// Task #1
result = await myFunction();

Rss

# fetch rss entries and notify some webhook
- id: entries
  use: rss.entries
  args: https://actionsflow.github.io/test-page/hn-rss.xml

# You can visit https://requestbin.com/r/enyvb91j5zjv9/23eNPamD4DK4YK1rfEB1FAQOKIj
# to check the http request.
- loop: $entries
  use: fetch
  args:
    - https://enyvb91j5zjv9.x.pipedream.net/
    - method: POST
      headers:
        Content-Type: application/json
      body: |
        {
          "title": "${item.title.value}",
          "link":  "${item.links[0].href}"
        }

This will be compiled to:

import { rss } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
let result = null;
let index = 0;

// Task #0: entries
result = await rss.entries(`https://actionsflow.github.io/test-page/hn-rss.xml`);
const entries = result;

// Task #1
for await (const item of entries){
  result = await fetch(`https://enyvb91j5zjv9.x.pipedream.net/`,{
    "method" : `POST`,
    "headers": {
      "Content-Type" : `application/json`
    },
    "body" : `{
      "title": "${item.title.value}",
      "link":  "${item.links[0].href}"
    }
    `
  });
  index++;
}
index=0;

Cache

# what if we want to deduplicate the rss items?
- id: entries
  use: rss.entries
  args: https://actionsflow.github.io/test-page/hn-rss.xml

- name: get cache
  id: kv
  use: fsExtra.readJSONFileWithDefaultValue
  args:
    - ./.yamlscript/cache/kv.json
    - ${}
- use: defn
  id: handleRssEntry
  args:
    - use: return
      if: kv[args[0].links[0].href]
    - name: notify
      use: fetch
      args:
        - https://enyvb91j5zjv9.x.pipedream.net/
        - method: POST
          headers:
            Content-Type: application/json
          body: |
            {
              "title": "${args[0].title.value}",
              "link":  "${args[0].links[0].href}"
            }
    - use: _.assign
      args:
        - $kv
        - $[args[0].links[0].href]: true

# You can visit https://requestbin.com/r/enyvb91j5zjv9/23eNPamD4DK4YK1rfEB1FAQOKIj
# to check the http request.
- loop: $entries
  use: handleRssEntry
  args: $item

- name: set to cache
  use: fsExtra.writeJSONFile
  args:
    - ./.yamlscript/cache/kv.json
    - $kv

This will be compiled to:

import { rss } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
import { fsExtra } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
import { _ } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
let result = null;
let index = 0;

// Task #0: entries
result = await rss.entries(`https://actionsflow.github.io/test-page/hn-rss.xml`);
const entries = result;

// Task #1: get cache
result = await fsExtra.readJSONFileWithDefaultValue(`./.yamlscript/cache/kv.json`,{});
const kv = result;

// Task #2: handleRssEntry
async function handleRssEntry(...args){

  // Task #2_0
  if (kv[args[0].links[0].href]) {
    return;
  }

  // Task #2_1  : notify
  result = await fetch(`https://enyvb91j5zjv9.x.pipedream.net/`,{
    "method" : `POST`,
    "headers": {
      "Content-Type" : `application/json`
    },
    "body" : `{
      "title": "${args[0].title.value}",
      "link":  "${args[0].links[0].href}"
    }
    `
  });

  // Task #2_2
  result = await _.assign(kv,{
    [args[0].links[0].href] : true
  });

  return result;
}

// Task #3
for await (const item of entries){
  result = await handleRssEntry(item);
  index++;
}
index=0;

// Task #4: set to cache
result = await fsExtra.writeJSONFile(`./.yamlscript/cache/kv.json`,kv);

Define Global Variables

# Sometimes we need to define a global var in child block
# We can use `defg` to define a global variable.
- use: Math.max
  args:
    - 1
    - 9

- if: result===9
  use: defg
  id: foo
  args: bar

- use: assertEquals
  args:
    - $foo
    - bar

This will be compiled to:

import { assertEquals } from "https://raw.githubusercontent.com/yamlscript/yamlscript/main/globals/mod.ts";
let result = null;
let foo = null;

// Task #0
result = await Math.max(1,9);

// Task #1: foo
if (result===9) {
  foo = `bar`;
}

// Task #2
result = await assertEquals(foo,`bar`);

Deno Deploy

- from: https://deno.land/std@0.149.0/http/server.ts
  use: serve
  args: $handler
  if: build.env.YAMLSCRIPT_DEV == "1"

- use: defn
  id: handler
  args:
    - use: new Response
      args: Hello World

This will be compiled to:

let result = null;

// Task #1: handler
async function handler(...args){

  // Task #1_0
  result = await new Response(`Hello World`);

  return result;
}

Install

Yamlscript depends on Deno, so you should install Deno first.
Install YAMLScript by running deno install -A https://deno.land/x/YAMLScript/ys.ts

Cli

  Usage:   ys
  Version: 0.0.1

  Description:

    yamlscript is written in yaml format and can be compiled into javscript that runs in deno.

  Options:

    -h, --help     - Show this help.
    -V, --version  - Show the version number for this program.
    -v, --verbose  - Enable verbose output.

  Commands:

    run    [file...]  - run files
    build  [file...]  - build yaml file to js file

# run some files
ys run a.ys.yml
ys run **/*.yml
ys run a.ys.yml b.ys.yml
# run all .ys.yml files
ys run -A
# run some directories
ys run -d a/b/c

# build is same as run
ys build a.ys.yml

Notes

This README.md file is generated by the following YAMLScript.

# get readme.template.md content
- id: readmeTemplate
  use: Deno.readTextFile
  args: ./docs/README.tmpl.md

# get yaml content
- id: yamlMakeReadmeScript
  use: Deno.readTextFile
  args: ./docs/make_readme.ys.yml

# get source content and target
- use: defn
  id: mapFiles
  args:
    - id: sourceContent
      use: Deno.readTextFile
      args: ${args[0]}
    - id: sourceTasks
      use: fsExtra.readYAMLFile
      args: ${args[0]}
    - id: targetCode
      use: YAMLScript.getCompiledCode
      args:
        - $sourceTasks
    - id: title
      from: https://deno.land/x/case@2.1.1/mod.ts
      use: titleCase
      args: ${args[2].slice(3,-7)}
    - use: return
      args:
        title: $title
        source: $sourceContent
        target: <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>t</mi><mi>a</mi><mi>r</mi><mi>g</mi><mi>e</mi><mi>t</mi><mi>C</mi><mi>o</mi><mi>d</mi><mi>e</mi><mi mathvariant="normal">.</mi><mi>t</mi><mi>o</mi><mi>p</mi><mi>L</mi><mi>e</mi><mi>v</mi><mi>e</mi><mi>l</mi><mi>C</mi><mi>o</mi><mi>d</mi><mi>e</mi></mrow><annotation encoding="application/x-tex">{targetCode.topLevelCode}</annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8889em;vertical-align:-0.1944em;"></span><span class="mord"><span class="mord mathnormal">t</span><span class="mord mathnormal">a</span><span class="mord mathnormal" style="margin-right:0.02778em;">r</span><span class="mord mathnormal" style="margin-right:0.03588em;">g</span><span class="mord mathnormal">e</span><span class="mord mathnormal" style="margin-right:0.07153em;">tC</span><span class="mord mathnormal">o</span><span class="mord mathnormal">d</span><span class="mord mathnormal">e</span><span class="mord">.</span><span class="mord mathnormal">t</span><span class="mord mathnormal">o</span><span class="mord mathnormal">p</span><span class="mord mathnormal">L</span><span class="mord mathnormal">e</span><span class="mord mathnormal" style="margin-right:0.03588em;">v</span><span class="mord mathnormal">e</span><span class="mord mathnormal" style="margin-right:0.07153em;">lC</span><span class="mord mathnormal">o</span><span class="mord mathnormal">d</span><span class="mord mathnormal">e</span></span></span></span></span>{targetCode.mainFunctionBodyTopLevelCode}${targetCode.mainFunctionBodyCode}

# get simple usage sources and targets
- id: simpleUsageFiles
  use: Deno.readDirSync
  args: ./docs/simple-usage

- loop: $simpleUsageFiles
  id: simpleUsageFileNames
  use: _.get
  args:
    - $item
    - name
# sort
- id: sortedSimpleUsageFiles
  use: _.sortBy
  args:
    - $simpleUsageFileNames

- id: simpleUsageSources
  loop: $sortedSimpleUsageFiles
  use: mapFiles
  args:
    - ./docs/simple-usage/${item}
    - $index
    - $item
# get advanced usage sources and targets
- id: advancedFiles
  use: Deno.readDir
  args: ./docs/advanced

- loop: $advancedFiles
  id: advancedFileNames
  use: _.get
  args:
    - $item
    - name
# sort
- id: sortedAdvancedFiles
  use: _.sortBy
  args:
    - $advancedFileNames

- id: advancedSources
  loop: $sortedAdvancedFiles
  use: mapFiles
  args:
    - ./docs/advanced/${item}
    - $index
    - $item
# use mustache to render readme.template.md
- id: readmeContent
  from: https://esm.sh/mustache@4.2.0
  use: default.render
  args:
    - $readmeTemplate
    - simpleUsageSources: $simpleUsageSources
      advancedSources: $advancedSources
      yamlMakeReadmeScript: $yamlMakeReadmeScript

# readme content to generate toc

# write to readme.md
- use: Deno.writeTextFile
  args:
    - README.md
    - $readmeContent

See all built-in functions

Inspired by Common Lisp, Clojure, Denoflow, Rash, Comtrya