~tilde

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Limitations ​

What Tilde does not do yet, and what it does quietly rather than loudly. Written so you can tell a bug from a gap.

Anything here is a gap. If Tilde does something not described on this page and not described elsewhere in the docs, that is worth reporting.

Answers chosen for you ​

A drawing has to start somewhere, and when a figure is genuinely ambiguous something has to settle on one version of it. Both are choices your program did not make, and both are invisible in the result.

point a at 0 0
point b
line l through a b

Only a is actually determined here. b is placed at the origin because nothing says otherwise, and the line through two identical points comes out at an arbitrary angle.

To see which parts are yours: switch the strategy picker in the playground to none. It draws only what your constraints force, and leaves out everything that was being chosen for you.

Contradictions are quiet ​

Asking for something impossible does not stop the drawing or report anything. The impossible part is left out and the rest is drawn.

scalar r = 2
r = 3            -- r cannot be both, so it has no value and is not drawn

Nothing marks it as impossible on the canvas. You find out by noticing something missing.

Ambiguous figures ​

Where a figure has two possible versions, Tilde draws and prints both. There is no way yet to choose one — pick went with the classic syntax and is on the roadmap. Saying something more that rules one out is the only way to settle it.

The language ​

How a line is read is described in Reading a Line.

Not available at all: pick, units, angles, lines by equation, and the other things that went with the classic syntax — listed on the roadmap.

Arithmetic works only on numbers written out. scalar r = ((2 + 3) * 4) is 20, but (k + 1) with a named k is refused — a named number is worked out after the arithmetic runs, so there is nothing to add yet.

Where anything would do, a two-way group has to be named first. If a pair of numbers can mean a point or a line, the slot it lands in decides — but print takes anything, so print (2, 1) is refused until the pair is named (point p = (2, 1), then print p). = cannot pass a type across from one side to the other yet either.

You can reach a shape's parts but not a shape's numbers. t.point1 gives you a triangle's corner, because a corner is a whole point. There is no p.x — see the roadmap for why that is harder than it looks.

Two points said to be the same stay two points. p = q holds them at no distance apart, drawn on top of each other, rather than making them one point — that waits on = learning to merge. (Two numbers, r = w, already are one.)

A definition's helper shapes are not drawn. A name used only inside a definition ends when the definition finishes, and so does any way of showing what it named. The shape still counts — if it holds something else in place, that still holds — but it does not appear. To show a part of what a definition builds, make it a field of the thing's type, or build it under the name the caller supplied. A way to ask for a helper to be drawn is planned.

A definition can only use what its own file imported. Importing a file does not give you what it imported. This is deliberate, and matches how most languages work, but it means a shape you got from elsewhere may not be one you can say anything about without importing more.