Inspecting inferred types

Rigor’s analysis is invisible by default — it only speaks up to report a diagnostic. When you want to see what type the engine assigns an expression, there are four tools: two source helpers and two CLI commands.

dump_type — print a type from source

dump_type(expr) makes Rigor emit an info-severity dump.type diagnostic showing the inferred type of expr. At runtime it is a no-op that returns expr unchanged, so it is safe to leave in or sprinkle freely while debugging.

require "rigor/testing"
include Rigor::Testing

dump_type(1 + 2)   # rigor reports: dump.type — Constant<3>

Rigor recognises the call when it is written as dump_type(…) after include Rigor::Testing, or fully qualified as Rigor::Testing.dump_type(…) / Rigor.dump_type(…).

assert_type — pin a type in source

assert_type("TypeString", expr) compares expr’s inferred type against the literal type string. On a mismatch Rigor emits an error-severity assert.type-mismatch diagnostic; on a match it stays silent. Like dump_type, it returns expr unchanged at runtime.

assert_type("Constant<3>", 1 + 2)   # silent — matches
assert_type("Integer",     1 + 2)   # assert.type-mismatch

The type string is matched against the engine’s short display form. assert_type is how the handbook’s examples stay honest, and it doubles as a regression check you can keep in a project’s own test sources.

rigor annotate — types in the margin

rigor annotate FILE reprints a whole file with every line tagged by the type of the expression it evaluates to, as a trailing #=> dump_type: comment:

two = 1 + 1   #=> dump_type: 2
name = gets   #=> dump_type: String | nil

It is the fastest way to survey a file. The annotation is idempotent — re-running replaces the previous comment rather than stacking it. Output is syntax-highlighted for a tty; --no-color (and the NO_COLOR environment variable) disable the colour.

rigor type-of — one position

When you only need one expression’s type — typically while chasing down why a diagnostic did or did not fire — query a single position:

rigor type-of lib/example.rb:12:8

--format=json emits a machine-readable result for tooling. This is the same query the editor integration answers on hover.

Which to reach for

You want…	Use
One expression’s type, from the shell	rigor type-of
Every line of a file surveyed	rigor annotate
A type printed mid-analysis, in context	dump_type
A type asserted and regression-checked	assert_type