Compose signup validation steps with Result while preserving actionable failure reasons.
The signup validator returns false for any failure, but product needs a reason and support needs a user-facing next step. Railway Oriented Programming: each step returns Ok(next) or Err(reason). The novice move is to keep a boolean return and log the reason elsewhere. That creates a side channel the caller cannot reliably use. Step 1 normalizeEmail(input.email) -> Result. The first step turns raw text into a trusted domain value or returns a specific reason. Step 2 checkRegion(email, country) -> Result. The second step receives a valid email and adds regional eligibility. Step 3 reserveAccount(lead) -> Result. Reservation can fail for…
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