improve trace utils

src/composition.ts

@@ -1,8 +1,9 @@
-import { last, reverse } from "./array.ts";
+import { reverse } from "./array.ts";
 import { AnyAsync, Func, Last, ReturnTypeUnwrapped } from "./typing.ts";
 
 import { not } from "./operator.ts";
 import { reduce } from "./reduce.ts";
+import { currentLocation } from "./trace.ts";
 
 type UnaryFn<A, R> = (a: A) => R;
 type Arg<F extends Func> = Parameters<F>[0];
@@ -34,35 +35,13 @@ const pipeWithoutStack = <Fs extends Func[]>(
       Fs
     >;
 
-interface StackFrame {
-  file: string;
-  line: number;
-  column: number;
-}
-
-const frameToString = ({ line, file, column }: StackFrame) =>
-  `${file}:${line}:${column}`;
-
-const parseStackLine = (stackLine: string): null | StackFrame => {
-  const matches = RegExp(/\s+at\s+(.+\s)?\(?(.+):(\d+):(\d+)\)?/).exec(
-    stackLine,
-  );
-  if (!matches) return null;
-  const [, , file, line, column] = matches;
-  return { file, line: parseInt(line), column: parseInt(column) };
-};
-
-const parseStackTrace = (trace: string) =>
-  parseStackLine(last(trace.split("\n")));
-
 const errorBoundry = <F extends Func>(f: F) => {
-  const err = new Error().stack as string;
+  const codeLocation = currentLocation();
   return ((...x) => {
     try {
       return f(...x);
     } catch (e) {
-      const lastStackCall = parseStackTrace(err);
-      if (lastStackCall) console.error(frameToString(lastStackCall));
+      console.error(codeLocation);
       throw e;
     }
   }) as F;

src/debug.ts

@@ -1,37 +1,41 @@
 import { Func, ReturnTypeUnwrapped } from "./typing.ts";
 
+import { currentLocation } from "./trace.ts";
 import { sideEffect } from "./composition.ts";
 
 export const sideLog = <T>(x: T) => {
-  console.log(x);
+  console.log(currentLocation(), x);
   return x;
 };
 
-export const sideLogAfter = <F extends Func>(f: F): F =>
-  ((...xs) => {
+export const sideLogAfter = <F extends Func>(f: F): F => {
+  const codeLocation = currentLocation();
+  return ((...xs) => {
     const output = f(...xs);
     if (output instanceof Promise) {
       return output.then((x) => {
-        console.log(x);
+        console.log(codeLocation, x);
         return x;
       }) as ReturnType<F>;
     }
-    console.log(output);
+    console.log(codeLocation, output);
     return output;
   }) as F;
+};
 
-export const sideLogBefore = <F extends Func>(f: F): F =>
-  ((...xs) => {
-    console.log(xs.length === 1 ? xs[0] : xs);
+export const sideLogBefore = <F extends Func>(f: F): F => {
+  const codeLocation = currentLocation();
+  return ((...xs) => {
+    console.log(codeLocation, xs.length === 1 ? xs[0] : xs);
     const output = f(...xs);
     if (output instanceof Promise) {
       return output.then((x) => {
         return x;
       }) as ReturnType<F>;
     }
-    console.log(output);
     return output;
   }) as F;
+};
 
 export const sideLogTable = sideEffect(console.table);
 // deno-lint-ignore no-explicit-any

src/trace.ts

@@ -0,0 +1,22 @@
+interface StackFrame {
+  file: string;
+  line: number;
+  column: number;
+}
+const frameToString = ({ line, file, column }: StackFrame) =>
+  `${file}:${line}:${column}`;
+
+const parseStackLine = (stackLine: string): StackFrame => {
+  const matches = RegExp(/\s+at\s+(.+\s)?\(?(.+):(\d+):(\d+)\)?/).exec(
+    stackLine,
+  );
+  if (!matches) throw new Error("could not figure out stack line");
+  const [, , file, line, column] = matches;
+  return { file, line: parseInt(line), column: parseInt(column) };
+};
+
+const parseStackTrace = (trace: string, picker: (lines: string[]) => string) =>
+  parseStackLine(picker(trace.split("\n")));
+
+export const currentLocation = () =>
+  frameToString(parseStackTrace(new Error().stack as string, (x) => x[3]));