The solution is to use javascript. For now.
Some of the methods we use here, such as Blob aren’t yet implemented in ReasonML (or I just couldn’t find them), so we need to put some javascript into our ReasonML code using interop.
Here’s a working version using codesandbox you can play with.
https://codesandbox.io/s/how-to-download-arbitrary-data-reasonml-yoxyg
Javascript Interop
In ReasonML, you can wrap javascript with [%bs.raw {| ...code goes here... |}] and it is accessible to the Reason code.
How Downloading works
First, we create a blob (Binary Large OBject) with our text MIME type.
var content = new Blob(["I AM TEXT"], {type: "text/plain"});Then we create an object url that can reference the data in our Blob and we add this url to the anchor tag.
document.getElementById("download")
.setAttribute("href", window.URL.createObjectURL(content));Lastly, we set the download attribute so that we can name our downloaded file.
document.getElementById("download")
.setAttribute("download", fileName);In conclusion, the link to the blob causes the browser to download the file, and gives it our name.
All the code together:
index.html
<html>
<body>
<a href="" id="download">Download File</a>
</body>
</html>index.re
let setupDownload = [%bs.raw
{|
function() {
var fileName = "data.txt";
var content = new Blob(["I AM TEXT"], {type: "text/plain"});
document.getElementById("download")
.setAttribute("href", window.URL.createObjectURL(content));
document.getElementById("download")
.setAttribute("download", fileName);
}
|}
];
setupDownload();