Effect.if evaluates onTrue when condition is false

[alex-dixon]

What version of Effect is running?

2.2.3

What steps can reproduce the bug?

import { Effect } from 'effect'

const f = (s: string) => Effect.succeed(s)

const foo: { bar?: { baz: string } } = {}

Effect.runSync(
  Effect.if('bar' in foo, {
    onTrue: f(foo.bar!.baz),
    onFalse: Effect.fail('oops'),
  })
)

What is the expected behavior?

onTrue does not evaluate when truth test is false

What do you see instead?

/repro/scratch.ts:9
    onTrue: f(foo.bar!.baz),
                       ^
TypeError: Cannot read properties of undefined (reading 'baz')
    at Object.<anonymous> (/repro/scratch.ts:9:24)
    at Module._compile (node:internal/modules/cjs/loader:1368:14)
    at Module.m._compile (/repro/node_modules/ts-node/src/index.ts:1618:23)

Additional information

No response

[tim-smart]

You will need to wrap it with Effect.suspend

[mikearnaldi]

You will need to wrap it with Effect.suspend

might be worth considering if conditional branches should be lazy, while the fact that the branch would evaluate is pretty obvious from JS eager evaluation semantics the golden path should be not to evaluate the branch

[tim-smart]

Closed by #2451