1 files changed, 34 insertions, 0 deletions

diff --git a/src/utils.js b/src/utils.js
new file mode 100644
index 0000000..671b580
--- /dev/null
+++ b/src/utils.js
@@ -0,0 +1,34 @@
+const path = require('path');
+
+exports.PscError = class PscError extends Error {
+  constructor(message, modules) {
+    super(message);
+    this.modules = modules;
+  }
+
+  static get name() {
+    return 'PscError';
+  }
+};
+
+const repeat = (value, times) =>
+  times <= 0 ? [] : [value, ...repeat(value, times - 1)];
+const diffPursModuleNames = (from, target, parts) => {
+  if (!from.length) return parts.concat(target);
+  if (!target.length) return parts.concat(repeat('..', from.length));
+  const [head_from, ...tail_from] = from;
+  const [head_target, ...tail_target] = target;
+  return head_from === head_target
+    ? diffPursModuleNames(tail_from, tail_target, parts)
+    : parts.concat(repeat('..', from.length), target);
+};
+exports.resolvePursModule = ({ baseModulePath, baseModuleName, targetModuleName }) => {
+  const parts = diffPursModuleNames(
+    baseModuleName.split('.'),
+    targetModuleName.split('.'),
+    []);
+  return parts.length
+    ? path.resolve(baseModulePath,
+      `${path.join(...parts)}.purs`)
+    : baseModulePath;
+};