Developing-Hadrian.md

@@ -6,14 +6,14 @@ Shake, Hadrian's underlying build system, has a cloud shared cache feature. This
 
 * **Direct Dependency**: All files read by a rule are direct dependencies of that rule
 * **Direct Output**: All files created by a rule that are the target of the rule or are direct dependencies of other rules.
-* **Vital Output**: a subset of direct outputs that are the target of the current rule or are vital inputs of any other rule.
-* **Vital Input**: a subset of direct dependencies that excludes files whose existence have no affect on the vital output (i.e. cache files of external tools).
-* **Shallow Dependency**: A subset of the direct dependencies such that: *no change in the shallow dependencies -> no change in the vital output*. This set is not unique (the direct dependencies are trivially a set of shallow dependencies), but we try to define this as a minimal (or close to minimal) set. With respect to a rule for a haskell object file X.o, the shallow dependencies are the source file X.hs and interface files Y.hi (or Y.hi-boot) for all modules Y imported by X (see [makefile-dependencies](https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/separate_compilation.html#makefile-dependencies)). These are the dependencies of X.o as reported by `ghc -M X.hs`. Note that this is a sufficient set as ghc guarantees that the shallow .hi dependencies will change if the deep .hi dependencies change.
+* **Vital Dependency**: a subset of direct dependencies that excludes files whose existence have no affect on the vital output (i.e. cache files of external tools).
+* **Vital Output**: a subset of direct outputs that are the target of the current rule or are vital dependencies of any rule.
+* **Shallow Dependency**: A subset of the direct dependencies such that: *no change in the shallow dependencies -> no change in the vital output*. This set is not unique (the direct dependencies are trivially a set of shallow dependencies), but we try to define this as a minimal (or close to minimal) set. With respect to a rule for a haskell object file X.o, the shallow dependencies are the source file X.hs and interface files Y.hi (or Y.hi-boot) for all modules Y imported by X (see [makefile-dependencies](https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/separate_compilation.html#makefile-dependencies)). These are the dependencies of X.o as reported by `ghc -M X.hs`. Note that ghc reads some transitively imported module's .hi files, but those files are deep dependencies as ghc guarantees that the shallow .hi dependencies (directly imported modules) will change if the deep .hi dependencies (transitively imported modules) change.
 * **Deep Dependency**: The direct dependencies minus the shallow dependencies. With respect to a rule for a haskell object file X.o, the deep dependencies are all hi/hi-boot files required by ghc to build X.o excluding direct dependencies. This is a subset of modules transitively imported by X. These dependencies are NOT reported by `ghc -M X.hs`
 
 Properties:
 * Shallow Dependency ∪ Deep Dependency = Direct Dependency
-* Shallow Dependency ⊆ Vital Input ⊆ Direct Dependency
+* Shallow Dependency ⊆ Vital Dependency ⊆ Direct Dependency
 * Vital Output ⊆ Direct Output
 
 Consider this scenario:
@@ -25,10 +25,10 @@ Consider this scenario:
 
 In this case the rule to build A.o via `ghc -c A.hs` has:
 
-* Direct dependencies: A.hs, B.hi, C.hi
+* Direct Dependencies: A.hs, B.hi, C.hi
 * Direct Outputs: A.o, A.hi  (Note the -c option also produces .hi files)
-* Vital inputs: A.hs, B.hi, C.hi
-* Vital outputs: A.o, A.hi  (Assuming another rule will have A.hi as a vital input)
+* Vital Dependencies: A.hs, B.hi, C.hi
+* Vital outputs: A.o, A.hi  (Assuming another rule will have A.hi as a vital dependency)
 * Shallow Dependencies: A.hs, B.hi
 * Deep Dependencies: C.hi