CONST

CONST is the first Tiny Interpreters interpreter. A complete program is just a non-negative integer literal:

123

That lets us follow a complete program from source text to an evaluated value:

flowchart TD
    A["123"] -->|parse| B["Program (Const 123)"]
    B -->|evaluate| C["VNumber 123"]

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For a closer look at each step, read CONST: From Source Text to Value.

To try it, you'll need Nix with flakes enabled.

nix develop
elm repl

Then:

import CONST.Interpreter as I

I.run "123"
-- Ok (VNumber 123)