add Effect.functionWithSpan

.changeset/lovely-frogs-scream.md

@@ -0,0 +1,19 @@
+---
+"effect": minor
+---
+
+add Effect.functionWithSpan
+
+Allows you to define an effectful function that is wrapped with a span.
+
+```ts
+import { Effect } from "effect"
+
+const getTodo: (id: number) => Effect.Effect<string> = Effect.functionWithSpan({
+  body: (id: number) => Effect.succeed(`Got todo ${id}!`),
+  options: (id) => ({
+    name: `getTodo-${id}`,
+    attributes: { id }
+  })
+})
+```

packages/effect/src/Effect.ts

@@ -5274,6 +5274,40 @@ export const withSpan: {
   ): Effect<A, E, Exclude<R, Tracer.ParentSpan>>
 } = effect.withSpan
 
+/**
+ * Wraps a function that returns an effect with a new span for tracing.
+ *
+ * @since 3.2.0
+ * @category models
+ */
+export type FunctionWithSpanOptions<Params extends ReadonlyArray<any>> =
+  | (Omit<Tracer.SpanOptions, "captureStackTrace"> & { readonly name: string })
+  | ((...args: Params) => Omit<Tracer.SpanOptions, "captureStackTrace"> & { readonly name: string })
+
+/**
+ * Wraps a function that returns an effect with a new span for tracing.
+ *
+ * @since 3.2.0
+ * @category tracing
+ * @example
+ * import { Effect } from "effect"
+ *
+ * const getTodo: (id: number) => Effect.Effect<string, never, never> = Effect.functionWithSpan({
+ *   body: (id: number) => Effect.succeed(`Got todo ${id}!`),
+ *   options: (id) => ({
+ *     name: `getTodo-${id}`,
+ *     attributes: { id }
+ *   })
+ * })
+ */
+export const functionWithSpan: <Fn extends (...args: ReadonlyArray<any>) => Effect<any, any, any>>(
+  options: {
+    readonly body: Fn
+    readonly options: FunctionWithSpanOptions<Parameters<Fn>>
+    readonly captureStackTrace?: boolean | undefined
+  }
+) => Fn = effect.functionWithSpan
+
 /**
  * Wraps the effect with a new span for tracing.
  *

packages/effect/src/internal/core-effect.ts

@@ -2162,6 +2162,37 @@ export const withSpan: {
   return (self: Effect.Effect<any, any, any>) => useSpan(name, options, (span) => withParentSpan(self, span))
 } as any
 
+export const functionWithSpan = <Fn extends (...args: ReadonlyArray<any>) => Effect.Effect<any, any, any>>(
+  options: {
+    readonly body: Fn
+    readonly options: Effect.FunctionWithSpanOptions<Parameters<Fn>>
+    readonly captureStackTrace?: boolean | undefined
+  }
+): Fn =>
+  (function(this: any) {
+    let captureStackTrace: Error | boolean = options.captureStackTrace ?? false
+    if (options.captureStackTrace !== false) {
+      const limit = Error.stackTraceLimit
+      Error.stackTraceLimit = 2
+      const error = new Error()
+      Error.stackTraceLimit = limit
+      if (error.stack !== undefined) {
+        const stack = error.stack.trim().split("\n")
+        error.stack = stack.slice(2).join("\n").trim()
+        captureStackTrace = error
+      }
+    }
+    return core.suspend(() => {
+      const opts = typeof options.options === "function"
+        ? options.options.apply(null, arguments as any)
+        : options.options
+      return withSpan(options.body.apply(this, arguments as any), opts.name, {
+        ...opts,
+        captureStackTrace
+      })
+    })
+  }) as any
+
 // -------------------------------------------------------------------------------------
 // optionality
 // -------------------------------------------------------------------------------------