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Author SHA1 Message Date
a7b1b206be feat: can pass content as flags 2025-10-15 13:00:58 +02:00
10 changed files with 117 additions and 74 deletions

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elm 0.19.1
python 3.13.1-v2

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@@ -22,8 +22,8 @@ Next, we concatenate this with the Elm JavaScript output and an app launcher sni
## Limitations
* No event loop
* Hence, no [TEA](https://guide.elm-lang.org/architecture/); the `main` function must return a static view
* Hence, no Time, no Random, no Json Encoder/Decoder (!), no Http
* Hence, no [TEA](https://guide.elm-lang.org/architecture/); no `update` can be triggered
* Hence, no Time, no Random, no Http
* Nodes can only have one parent (this should always be the case)
* Does not scale well : creating thousands of Nodes consumes a [lot of RAM](#Performances)
@@ -37,19 +37,73 @@ Next, we concatenate this with the Elm JavaScript output and an app launcher sni
```elm
module Hello exposing(main)
import Html exposing (p, text)
import Html exposing (text)
main = p [] [text "Hello World!"]
main = text "Hello World!"
```
4. Run `./build.sh src/Hello.elm`; this generates the corresponding HTML code:
4. Run `./elmscript.sh src/Hello.elm`
```html
<p>
This produces the expected output:
```text
Hello World!
</p>
```
## passing input
Input content can be passed to the script via the standard input. The content is then passed to the Elm script as "flags". The script must then use `Browser.element` and implement `init flags` function.
Create `src/Greet.elm` with the following content:
```elm
module Greet exposing (main)
import Browser
import Html exposing (text)
main =
Browser.element
{ init = \f -> (f, Cmd.none)
, update = \m _ -> (m, Cmd.none)
, view = \m -> text ("hello " ++ m)
, subscriptions = always Sub.none
}
```
Run `./elmscript.sh src/Greet.elm <<< 'Elm'`
This produces the expected output: `hello Elm`.
I's even more natural when passing file :
* run `elm install elm-explorations/markdown`
* create `src/MdRender.elm` with the following content:
```elm
module MdRender exposing (main)
import Browser
import Html.Attributes exposing (class)
import Markdown
main =
Browser.element
{ init = \s -> (s, Cmd.none)
, update = \m c -> (m, Cmd.none)
, view = \m -> Markdown.toHtml [class "content"] m
, subscriptions = always Sub.none
}
```
* run `./elmscript.sh src/MdRender.elm < README.md > README.html`
## Performances
Acceptable for small scripts : 250ms on a modest x86_64 CPU and 64MB RAM for a 500 records into a table ; but is does not scale well as everything is loaded before processing ; no streaming contrary to the usual Unix way.

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TODO.md
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# Major
- find a way to process external data
- [ ] from stdout (use case : json)
- [ ] find a way to process external data
- [x] from stdout (use case : json), use flags
- [ ] from files (use case : SSG)
- [ ] from http (use case : spider)
@@ -22,7 +22,7 @@
- [ ] in debug mode, keep the output
- [x] allow to specify or guess the main module name
- [x] if `innerHTML` attribute is set, output its value instead of the node tree
- [ ] allow to create standalone (`-s`) HTML document instead of fragment
- [ ] silence elm compiler message when successful
- [x] allow to create standalone (`-s`) HTML document instead of fragment => use template engine instead
- [x] silence elm compiler message when successful
- [ ] skip compilation steps if source has not been modified ; run directly ; this mean keeping the output
- [ ] add proper copyright and license
- [x] add proper copyright and license

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@@ -1,18 +0,0 @@
#!/bin/sh -eu
w1="$(mktemp out_$$_1_XXXX.js)"
elm make --output=${w1} $1 1>&2
sed -i -e 's!console.warn(!console.log(!g' ${w1}
w2="$(mktemp out_$$_XXXX.js)"
cat dom.js ${w1} launch.js > ${w2}
rm ${w1}
qjs --std ${w2}
# if qjs fails, output file will stay for debugging, else
rm ${w2}

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@@ -1,19 +0,0 @@
#!/bin/sh -eu
CMDD=$(dirname $(realpath 0))
w1="$(mktemp out_$$_1_XXXX.js)"
elm make --optimize --output=${w1} $1 1>&2
w2="$(mktemp out_$$_XXXX.js)"
cat ${CMDD}/dom.js ${CMDD}/preelm.js ${w1} ${CMDD}/postelm.js > ${w2}
rm ${w1}
qjs --std ${w2}
# if qjs fails, output file will stay for debugging, else
rm ${w2}

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dom.js
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@@ -5,6 +5,11 @@ function Node(parent, tag) {
this.text = null;
// attributes are stored directly on the node object
// see https://github.com/elm/virtual-dom/blob/master/src/Elm/Kernel/VirtualDom.js#L511
// but Html.Attributes.attribute/2 uses Element.setAttribute
this.setAttribute = (key, val) => {
// as of now, there is no check if key conflict with the ones defined by Dom implementation
this[key] = val;
}
this.children = []; // List of Node
this.replaceChild = (newNode, domNode) => {
this.children[domNode.pos-1] = newNode;
@@ -16,6 +21,9 @@ function Node(parent, tag) {
this.appendChild = (node) => {
node.pos = this.children.push(node);
}
this.replaceData = (offset, count, data) => {
this.text = data; // elm runtime will always replace the whole text
}
this.dump = (d=0) => {
if (this.text != null) {
print(this.text);

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elmscript.sh Executable file
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#!/bin/sh -eu
CMDD=$(dirname $(realpath 0))
w1="$(mktemp out_$$_1_XXXX.js)"
elm make --optimize --output=${w1} $1 1>/dev/null
w2="$(mktemp out_$$_XXXX.js)"
cat ${CMDD}/dom.js >> ${w2}
cat << EEE >> ${w2}
try {
EEE
cat ${w1} >> ${w2}
cat << EEE >> ${w2}
Elm[Object.keys(Elm)[0]].init({
node: document.getElementById("elm")
EEE
flags=$(grep -c 'main = $elm$browser$Browser$element' ${w1} || true)
if [ $flags -eq 1 ];
then
cat << EEE >> ${w2};
, flags: std.in.readAsString()
EEE
fi
cat << EEE >> ${w2}
});
document.children[0].dump();
} catch(e) {
throw e;
}
EEE
rm ${w1}
qjs --std ${w2}
# if qjs fails, output file will stay for debugging, else
rm ${w2}

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@@ -1,13 +0,0 @@
// above is the DOM implementation
// and the Elm app code
// here we lanch the app
Elm[Object.keys(Elm)[0]].init({ node: document.getElementById("elm") });
document.children[0].dump();
} catch(e) {
throw e;
}

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try {
// here will come the Elm app code

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#!/bin/sh -eu
countuniq0 build.sh dom.js postelm.js preelm.js