Your first SML program

The fastest way into ViSML is to build something small, watch the Code panel turn it into text as you go, and get the one caveat that matters — ViSML writes SML, it does not run it — out of the way early.

Opening ViSML

Open visml.l-workshop.my.id and you land on an empty workspace, the toolbox sidebar on the left, the Code panel on the right. There is nothing to install and nothing to sign in to — it is a static, client-side application, and everything you build stays in your browser until you export it.

Your first binding

Build the simplest possible program, a val binding:

1. From the Declaration category, open the Value/Variable subcategory and drag a dec_val block onto the workspace.
2. Give it a name in its identifier field — x is fine.
3. From Constant, drag an integer literal into the value socket and set it to 42.

The Code panel updates as you connect the blocks, and settles on val x = 42. That live sync is the thing to get used to: there is no separate “compile” step for the text view, because the generator runs on every edit.

Building Factorial

For something with more shape, load the Factorial example from the Examples menu rather than building it block by block on your first pass — it is the clearest illustration of what a recursive fun with multi-clause pattern matching looks like as blocks, and it is small enough to read in one screen.

With it loaded, generated code reads close to:

fun fact 0 = 1
  | fact n = n * fact (n - 1)
val result = fact 5

Click through the blocks that make up the two fact clauses and watch the corresponding lines highlight in the Code panel. Then try the reverse direction: edit the generated text directly and use Apply to Blocks to rebuild the workspace from it — this is covered in full in Code Generation.

Finding a block fast

Once you know the name of the block you want, dragging through ten categories is slower than searching for it. Press Ctrl + F to focus the toolbox's search field, type part of a block's name, and the matching categories open with the results highlighted. This is the fastest path once you have a rough sense of the grammar — see Blocks for the full category list.

ViSML does not run programs

Reading the status bar

Along the bottom edge: the current file name (Untitled workspace or the .vsml you loaded), the autosave state (Autosaved HH:MM once it has run), and the current perspective. Right-click the workspace background for Screenshot (exports the block diagram as a PNG — a picture of the blocks, not a code export) and About.