Record Types

Records are structurally typed immutable data.

Example

type User = {
  id: String,
  name: String,
  active: Boolean,
}

Rules

• compatibility is structural
• field order does not matter
• field names and field types must match
• record values are immutable

Draft 0.1 recommendation

Record shapes should be treated as closed by default. Unknown extra fields should not be silently accepted unless the language explicitly grows that capability later.

Why that matters

Closed-by-default expectations help:

• soundness
• diagnostics
• optimization

Comparison to TypeScript

TypeScript’s structural typing will feel familiar, but FScript is aiming for a tighter and more predictable shape model.