Debug

Tools for diagnosing programs.

CHECKPOINT(label)

• Parameters: optional label string
• Returns: true
• Example: CHECKPOINT("start")

ASSERT(cond[, msg])

• Parameters: cond – value tested for truthiness, optional msg string
• Returns: true if condition passes, otherwise error
• Example: ASSERT(1 == 1) → true

EXPLAIN(varName)

• Parameters: varName – name of variable
• Returns: provenance information or { "var": name, "info": "no provenance" }
• Example: EXPLAIN("x")