Improve sanity of trailing newline handling in command-line output

package.json

@@ -5,10 +5,11 @@
   "bin": {
     "please": "please"
   },
+  "//": "The ugly `bash -c` contortions in the scripts below are to work around <https://github.com/npm/cli/issues/8583>.",
   "scripts": {
-    "0": "node ./dist/language/cli/0.js",
-    "1": "node ./dist/language/cli/1.js",
-    "2": "node ./dist/language/cli/2.js",
+    "0": "bash -c 'node ./dist/language/cli/0.js \"$@\"; echo' bash",
+    "1": "bash -c 'node ./dist/language/cli/1.js \"$@\"; echo' bash",
+    "2": "bash -c 'node ./dist/language/cli/2.js \"$@\"; echo' bash",
     "build": "tsc --build tsconfig.app.json --force",
     "build:tests": "tsc --project tsconfig.app.json --outDir dist-test --declarationDir dist && tsc --build tsconfig.test.json",
     "clean": "rm -rf dist* *.tsbuildinfo",

src/language/cli/output.ts

@@ -69,19 +69,5 @@ export const writeOutput = (
     throw new Error(outputAsString.value.message)
   } else {
     writeStream.write(outputAsString.value)
-
-    // Writing a newline ensures that output is flushed before terminating,
-    // otherwise nothing may be printed to the console. See:
-    //  - <https://github.com/nodejs/node/issues/6379>
-    //  - <https://github.com/nodejs/node/issues/6456>
-    //  - <https://github.com/nodejs/node/issues/2972>
-    //  - …and many other near-duplicate issues
-    //
-    // I've tried other workarounds such as explicitly terminating via
-    // `process.exit`, passing a callback to `writeStream.write` (ensuring the
-    // returned `Promise` is not resolved until it is called), and explicitly
-    // calling `writeStream.end`/`writeStream.uncork` and so far this is the
-    // only workaround which reliably results in the desired behavior.
-    writeStream.write('\n')
   }
 }

src/language/unparsing.ts

@@ -1,4 +1,5 @@
 import type { Either } from '@matt.kantor/either'
+import either from '@matt.kantor/either'
 import type { UnserializableValueError } from './errors.js'
 import type { Atom, Molecule } from './parsing.js'
 import type { Notation } from './unparsing/unparsing-utilities.js'
@@ -13,6 +14,9 @@ export const unparse = (
   value: Atom | Molecule,
   notation: Notation,
 ): Either<UnserializableValueError, string> =>
-  typeof value === 'object'
-    ? notation.molecule(value, notation)
-    : notation.atom(value)
+  either.map(
+    typeof value === 'object'
+      ? notation.molecule(value, notation)
+      : notation.atom(value),
+    output => output.concat(notation.suffix),
+  )

src/language/unparsing/inline-plz.ts

@@ -39,4 +39,5 @@ const unparseMolecule = moleculeUnparser(
 export const inlinePlz: Notation = {
   atom: unparseAtom,
   molecule: unparseMolecule,
+  suffix: '',
 }

src/language/unparsing/pretty-json.ts

@@ -52,4 +52,5 @@ const unparseAtomOrMolecule = (value: Atom | Molecule) =>
 export const prettyJson: Notation = {
   atom: unparseAtom,
   molecule: unparseMolecule,
+  suffix: '\n',
 }

src/language/unparsing/pretty-plz.ts

@@ -39,4 +39,5 @@ const unparseMolecule = moleculeUnparser(
 export const prettyPlz: Notation = {
   atom: unparseAtom,
   molecule: unparseMolecule,
+  suffix: '\n',
 }

src/language/unparsing/sugar-free-pretty-plz.ts

@@ -30,4 +30,5 @@ const unparseAtomOrMolecule = (value: Atom | Molecule) =>
 export const sugarFreePrettyPlz: Notation = {
   atom: unparseAtom,
   molecule: unparseMolecule,
+  suffix: '\n',
 }

src/language/unparsing/unparsing-utilities.ts

@@ -9,6 +9,7 @@ export type Notation = {
     value: Molecule,
     notation: Notation,
   ) => Either<UnserializableValueError, string>
+  readonly suffix: string
 }
 
 export const indent = (spaces: number, textToIndent: string) => {