{
  "$schema": "../schema.json",
  "section": "variables",
  "description": "Variable initialisation, assignment as an expression, overwritable constants, and the finite clamp at the statement boundary.",
  "cases": [
    {
      "id": "uninitialized-reads-zero",
      "name": "an uninitialized variable reads as 0",
      "program": ["x = never_written * 3 + 1"],
      "expected": {
        "x": 1
      },
      "note": "Reading an unknown name is legal and yields 0. It is never an error, which is why a misspelled builtin fails silently."
    },
    {
      "id": "assignment-is-an-expression",
      "name": "assignment is an expression returning the assigned value",
      "program": ["y = (x = 3) + 1"],
      "expected": {
        "x": 3,
        "y": 4
      }
    },
    {
      "id": "pi-and-e-default",
      "name": "pi and e read as the mathematical constants by default",
      "program": ["x = pi", "y = e"],
      "expected": {
        "x": 3.141592653589793,
        "y": 2.718281828459045
      }
    },
    {
      "id": "pi-and-e-overwritable",
      "name": "pi and e are ORDINARY variables, so assignments to them stick",
      "program": ["pi = 4", "x = pi * 2", "e = 10", "y = e + 1"],
      "expected": {
        "x": 8,
        "y": 11
      },
      "note": "ns-eel registers pi/e as plain prepopulated variables. Around 74 presets in the bundled corpus overwrite one of them, so treating them as read-only constants breaks real content."
    },
    {
      "id": "nonfinite-clamped-at-store",
      "name": "a non-finite value is clamped to 0 when stored",
      "program": ["x = 1 / 0 + 5", "y = sqrt(4)"],
      "expected": {
        "x": 5,
        "y": 2
      },
      "note": "Here 1/0 is already 0 by the division guard, so x is 5. The clamp exists because expression state persists across frames: one unclamped Infinity poisons a variable for the preset's lifetime."
    },
    {
      "id": "case-insensitive-names",
      "name": "variable names are case-insensitive",
      "program": ["Foo = 3", "x = fOO + 1", "Zoom = 2", "y = zoom"],
      "expected": {
        "x": 4,
        "y": 2
      },
      "note": "ns-eel is case-insensitive: `contVol` and `contvol` are one variable, and `Zoom = 1.02` sets the `zoom` state field. Identifier reads normalise to lowercase, so a store that keeps the writer's casing silently disagrees with every read. Eight presets in the bundled corpus depend on this (six spell `contVol`/`contvol` inconsistently, two do the same with X1/Y1)."
    }
  ]
}