Values & types

Fluxon has the following basic types:

Important subtleties

Binary data (bytes)

For non-text data like images, PDFs, archives. There is no literal syntax — values come from functions: fs.readb path (binary file read), crypto.b64db s (binary-safe base64 decode), bytes.of s (text → its UTF-8 bytes). Core operations:

b = fs.readb "logo.png"     # bytes (nil if the file is missing)
bytes.len b                  # BYTE count (str.len counts CHARS)
bytes.str b                  # bytes → text (explicit error if not UTF-8)
bytes.slice b 0 4            # sub-bytes
fs.write "copy.png" b        # fs.write/append accept str or bytes
rep 200 b {content_type:"image/png"}   # raw binary HTTP response

In logs/interpolation bytes render as <bytes N> — raw bytes never leak into text. crypto.sha256/b64/hex inputs take str or bytes.

No commas in lists and maps

Elements are separated by spaces. This is intentional — commas waste tokens:

nums = [1 2 3 4]
user = {name:"Aziza" age:30 active:true}

Putting a variable inside text (interpolation)

With "${...}" you embed an expression inside text:

name = "Aziza"
log "Hello ${name}!"               # → Hello Aziza!
log "Total: ${price * qty} so'm"   # an expression also works

For a simple variable you can shorten it to "$name", but for an expression ${...} is required.

Multi-line text (block strings)

For long prompts, SQL, or templates use """. Content starts on the next line, and the common indentation of the lines is stripped automatically — so the block sits naturally inside indented code:

prompt = """
  You are a helpful agent.
  User question: ${question}
  """

If the closing """ is on its own line, the text has no trailing \n. Interpolation and \n/\t escapes work as in normal strings; " can be written freely without escaping (handy for JSON/HTML fragments).

Symbols — instead of enums

To represent states, use a symbol instead of text. :new, :confirmed — these are cheaper in tokens and clearer than the text "new":

status = :confirmed
dir = :in

When a symbol is converted to text (interpolation, str.str, +, log) the : prefix is dropped — the value is florist, the : is a syntax marker: str.str :florist → "florist", "path/${:florist}" → "path/florist". Inside a list/map, the : is kept ([:a] → [:a]), because there a symbol needs to stand out from text.

Truthiness

nil and false are falsy. Everything else (including 0, "", and the empty list) is truthy. This simple rule is intentional: only two things are falsy.