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+# pogen - string extraction for internationalizing TypeScript programs
+
+The ``pogen`` tool extracts internationalizable strings from TypeScript programs.
+
+
+## Invocation and Configuration
+
+The ``pogen`` tool must be called from the root of an NPM package.
+
+The input files are determined from the ``tsconfig.json`` file.  All input files inside the package that
+the compiler would use are automatically processed.
+
+Inside ``package.json``, the following configuration options are supported:
+
+```
+{
+
+  // [ ... ]
+
+  "pogen": {
+    // Output location of the pofile (mandatory)
+    "pofile": "...",
+
+    // Calls to plain i18n functions are extracted if they
+    // are imported from this package.
+    "plainI18nPackage": "@gnu-taler/taler-util",
+
+    // Calls to react-style i18n functions are extracted if they
+    // are imported from this package.
+    "reactI18nPackage": "@gnu-taler/preact-i18n",
+  }
+
+}
+```
+
+
+## Syntax
+
+Two flavors of syntax are supported:
+
+Template strings:
+
+```
+import { i18n } from "@gnu-taler/taler-util";
+
+console.log(i18n.str`Hello World`);
+console.log(i18n.str`Hello ${user}`);
+
+console.log(i18n.plural(n, i18n.lazy`I have ${n} apple`, i18n.lazy`I have ${n} apples`));
+```
+
+React components:
+
+```
+
+import {
+  Translate,
+  TranslateSwitch,
+  TranslateSingular,
+  TranslatePlural
+} from "@gnu-taler/preact-i18n";
+
+<Translate>Hello, World</Translate>
+
+// Placeholders are other React elements
+<Translate>Hello, <span className="highlight">{userName}<span></Translate>
+
+// Plain placeholders are not supported, they must be surrounded
+// by an element:
+// WRONG: <Translate>Hello, {userName}</Translate>
+
+<TranslateSwitch n={numApples}>
+  <TranslateSingular>I have <span>{n}</span> apple</TranslateSingular>
+  <TranslatePlural>I have <span>{n}</span> apple</TranslatePlural>
+</TranslateSwitch>
+
+```