Playground

This playground runs stringent’s runtime engine (safeParse + evaluateAst) right in your browser, against the quickstart grammar from Getting Started: number, string and true/false literals, variables and dotted paths, parentheses, == (overlap-typed), + (overloaded for numbers and strings), *, and a short-circuiting ternary.

Type an expression — parse errors show the exact position and what would have been valid there.

Expression

x * 2x * 2 == 42 ? 'yes' : 'no'user.name + '!'(1 + 2) * 3user.age == x + 15true ? 'taken' : user.name1 + 'a'

Result

"yes" (string)

Schema & values

schema = {
  "x": "number",
  "user": {
    "name": "string",
    "age": "number"
  }
}

values = {
  "x": 21,
  "user": {
    "name": "Ada",
    "age": 36
  }
}

The other engine

What you see here is the runtime half of stringent. The same grammar also drives the type-level engine, which checks string literals in your code at compile time — that part you can experience in the hover-able code blocks in the guides, or in your own editor.