Module 06 Glossary

Use these meanings while reading Module 06. The terms describe observable FuncPipe behavior, not merely page titles.

Flow operations

Term	Meaning in this module
context	A rule surrounding a value, such as possible failure, successful absence, read-only environment, changing local state, or ordered trace data.
map	Apply T -> U to a successful or present value while preserving the surrounding context.
map_err	Transform the error value of a Result without changing a success. This changes the error vocabulary and should preserve useful provenance.
and_then / bind	Apply T -> Context[U] to a successful value and keep one context layer. For Result and Option, the stopping variant skips the function.
short-circuit	Preserve a stopping case such as Err or NoneVal without evaluating the next dependent operation.
lift	Apply a plain function to values already inside one or more contexts without rewriting the plain function to accept containers.
applicative combination	Combine contextual inputs whose values do not depend on one another. Result remains fail-fast in Module 06; Validation accumulates independent failures.
dependent step	An operation that cannot run until an earlier operation produces a successful value.
independent input	An input that can be checked or produced without the successful value of another input.

Laws and evidence

Term	Meaning in this module
left identity	Introducing a value with the context’s success constructor before bind does not change the next operation’s result.
right identity	Binding a contextual value to its success constructor preserves the original contextual value.
associativity	Regrouping dependent operations without reordering them preserves the contextual result.
functor composition	Two pure map operations agree with one map containing the same composed function order.
law property	A property-based test of a structural rule over a bounded generated domain. It is not proof of a RAG business policy.
characterization test	A test that records existing public behavior before a refactor, whether or not that behavior is ideal.
equivalence property	A comparison of before and after observations over generated inputs. It supports preservation, not design superiority.

Explicit contexts

Term	Meaning in this module
Reader	A description equivalent to Environment -> Value, with operations for composing computations that share a read-only environment.
ask	A Reader description that returns the complete environment.
asks	A Reader description that selects a value from the environment.
local	Run a Reader description with a derived environment for that run. It does not mutate the caller’s environment.
State	A description equivalent to State -> (Value, State), used for explicit local state transitions.
initial state	The state value supplied by the caller to run_state; it is part of the program input.
Writer	A description that returns a payload and ordered trace entries without emitting them externally.
tell	A Writer description whose payload is None and whose meaningful output is one trace entry.
payload preservation	A wrapper returns the same domain value while adding context such as trace data or metrics.

Layering and boundaries

Term	Meaning in this module
outer context	The first decision in a nested type. In Result[Option[T], E], retrieval success or failure is decided before presence or absence.
layer order	The arrangement of two contexts; changing it can change failure, absence, state-retention, or trace-retention behavior.
transpose	Convert between two supported layer orders while preserving every modeled case.
successful absence	An operation completed correctly but found no value, represented by Ok(NoneVal()) in the retrieval example.
expected exception	A named exception from a narrow boundary operation that the caller can handle as a typed result.
unexpected exception	A defect or unmodeled failure that remains raised rather than being mislabeled as a domain error.
exception bridge	An adapter that runs one throwing operation, catches only declared expected classes, and maps them to Result or Validation.
assembly-time policy	Choosing wrappers while building a callable so the domain function does not inspect feature flags during every run.
endomorphic validator	A validator shaped T -> Result[T, E]; success preserves the input type so an existing pipeline can follow.

Application terms

Term	Meaning in this module
preservation claim	The earlier FuncPipe observation that must remain equal after a flow refactor: normalized values, chunk boundaries, order, embeddings, or error provenance.
call trace	A test-owned list recording which operations ran. It proves skipped or exactly-once work when result equality cannot.
context ledger	A comparison of the simplest direct representation with Reader, State, Writer, Result, or a wrapper, including the evidence required to justify the choice.
Module 06 reference state	capstone/module-reference-states/module-06/, the completed code and tests for explicit flow context before Module 07 effects.