Transfer Evolution

This page is generated from the local transfer fixture and the current effect-analyzer implementation.

Every Mermaid block below comes from static analysis of the TypeScript source in apps/docs/samples/observability-transfer/evolution.

No code is executed. If the analyzer changes, rerun pnpm --dir apps/docs run generate:transfer-observability and this page will update.

Step 1: Validate input

One operation. One possible failure. The type system already knows what can go wrong.

flowchart LR
  A["validated #lt;- deps.validateTransfer"] -->|ok| Done((Success))
  A -->|err| AE["Validation"]

Effects: 3
Error paths: ValidationError

Raw effect-analyze output

createSendMoneyWorkflow (generator):
  1. validated = Pipes deps.validateTransfer through:
    Calls deps.validateTransfer — collection

  Error paths: ValidationError
  Concurrency: sequential (no parallelism)

[
  {
    "program": "createSendMoneyWorkflow",
    "stats": {
      "totalEffects": 3,
      "parallelCount": 0,
      "raceCount": 0,
      "errorHandlerCount": 0,
      "retryCount": 0,
      "timeoutCount": 0,
      "resourceCount": 0,
      "loopCount": 0,
      "conditionalCount": 0,
      "layerCount": 0,
      "interruptionCount": 0,
      "unknownCount": 0,
      "decisionCount": 0,
      "switchCount": 0,
      "tryCatchCount": 0,
      "terminalCount": 0,
      "opaqueCount": 0
    }
  }
]

Step 2: + Fetch exchange rate

A second step, a second way to fail. The error channel grows automatically.

flowchart LR
  A["validated #lt;- deps.validateTransfer"] -->|ok| B["rate #lt;- deps.fetchRate"]
  B -->|ok| Done((Success))
  A -->|err| AE["Validation"]
  B -->|err| BE["RateUnavailable"]

Effects: 5
Error paths: RateUnavailableError, ValidationError

Raw effect-analyze output

createSendMoneyWorkflow (generator):
  1. validated = Pipes deps.validateTransfer through:
    Calls deps.validateTransfer — collection
  2. rate = Pipes deps.fetchRate through:
    Calls deps.fetchRate

  Error paths: RateUnavailableError, ValidationError
  Concurrency: sequential (no parallelism)

[
  {
    "program": "createSendMoneyWorkflow",
    "stats": {
      "totalEffects": 5,
      "parallelCount": 0,
      "raceCount": 0,
      "errorHandlerCount": 0,
      "retryCount": 0,
      "timeoutCount": 0,
      "resourceCount": 0,
      "loopCount": 0,
      "conditionalCount": 0,
      "layerCount": 0,
      "interruptionCount": 0,
      "unknownCount": 0,
      "decisionCount": 0,
      "switchCount": 0,
      "tryCatchCount": 0,
      "terminalCount": 0,
      "opaqueCount": 0
    }
  }
]

Step 3: + Check balance & convert

Balance check introduces a new failure mode. The compiler tracks it, you don’t have to.

flowchart LR
  A["validated #lt;- deps.validateTransfer"] -->|ok| B["rate #lt;- deps.fetchRate"]
  B -->|ok| C["balance #lt;- deps.getBalance"]
  C -->|ok| D["converted #lt;- deps.convertCurrency"]
  D -->|ok| Done((Success))
  A -->|err| AE["Validation"]
  B -->|err| BE["RateUnavailable"]
  D -->|err| DE["InsufficientFunds"]

Effects: 9
Error paths: InsufficientFundsError, RateUnavailableError, ValidationError

Raw effect-analyze output

createSendMoneyWorkflow (generator):
  1. validated = Pipes deps.validateTransfer through:
    Calls deps.validateTransfer — collection
  2. rate = Pipes deps.fetchRate through:
    Calls deps.fetchRate
  3. balance = Pipes deps.getBalance through:
    Calls deps.getBalance
  4. converted = Pipes deps.convertCurrency through:
    Calls deps.convertCurrency

  Error paths: InsufficientFundsError, RateUnavailableError, ValidationError
  Concurrency: sequential (no parallelism)

[
  {
    "program": "createSendMoneyWorkflow",
    "stats": {
      "totalEffects": 9,
      "parallelCount": 0,
      "raceCount": 0,
      "errorHandlerCount": 0,
      "retryCount": 0,
      "timeoutCount": 0,
      "resourceCount": 0,
      "loopCount": 0,
      "conditionalCount": 0,
      "layerCount": 0,
      "interruptionCount": 0,
      "unknownCount": 0,
      "decisionCount": 0,
      "switchCount": 0,
      "tryCatchCount": 0,
      "terminalCount": 0,
      "opaqueCount": 0
    }
  }
]

Step 4: + Execute transfer

The money moves. Two new failure modes from the external provider. Still zero runtime needed to see them.

flowchart LR
  A["validated #lt;- deps.validateTransfer"] -->|ok| B["rate #lt;- deps.fetchRate"]
  B -->|ok| C["balance #lt;- deps.getBalance"]
  C -->|ok| D["converted #lt;- deps.convertCurrency"]
  D -->|ok| E["transfer #lt;- deps.executeTransfer"]
  E -->|ok| Done((Success))
  A -->|err| AE["Validation"]
  B -->|err| BE["RateUnavailable"]
  D -->|err| DE["InsufficientFunds"]
  E -->|err| EE["TransferRejected / ProviderUnavailable"]

Effects: 11
Error paths: InsufficientFundsError, ProviderUnavailableError, RateUnavailableError, TransferRejectedError, ValidationError

Raw effect-analyze output

createSendMoneyWorkflow (generator):
  1. validated = Pipes deps.validateTransfer through:
    Calls deps.validateTransfer — collection
  2. rate = Pipes deps.fetchRate through:
    Calls deps.fetchRate
  3. balance = Pipes deps.getBalance through:
    Calls deps.getBalance
  4. converted = Pipes deps.convertCurrency through:
    Calls deps.convertCurrency
  5. transfer = Pipes deps.executeTransfer through:
    Calls deps.executeTransfer

  Error paths: InsufficientFundsError, ProviderUnavailableError, RateUnavailableError, TransferRejectedError, ValidationError
  Concurrency: sequential (no parallelism)

[
  {
    "program": "createSendMoneyWorkflow",
    "stats": {
      "totalEffects": 11,
      "parallelCount": 0,
      "raceCount": 0,
      "errorHandlerCount": 0,
      "retryCount": 0,
      "timeoutCount": 0,
      "resourceCount": 0,
      "loopCount": 0,
      "conditionalCount": 0,
      "layerCount": 0,
      "interruptionCount": 0,
      "unknownCount": 0,
      "decisionCount": 0,
      "switchCount": 0,
      "tryCatchCount": 0,
      "terminalCount": 0,
      "opaqueCount": 0
    }
  }
]

Step 5: + Send confirmation (complete)

The complete workflow. Six effects, six error channels, zero ambiguity. Every path is visible before a single line runs.

flowchart LR
  A["validated #lt;- deps.validateTransfer"] -->|ok| B["rate #lt;- deps.fetchRate"]
  B -->|ok| C["balance #lt;- deps.getBalance"]
  C -->|ok| D["converted #lt;- deps.convertCurrency"]
  D -->|ok| E["transfer #lt;- deps.executeTransfer"]
  E -->|ok| F["deps.sendConfirmation"]
  F -->|ok| Done((Success))
  A -->|err| AE["Validation"]
  B -->|err| BE["RateUnavailable"]
  D -->|err| DE["InsufficientFunds"]
  E -->|err| EE["TransferRejected / ProviderUnavailable"]
  F -->|err| FE["ConfirmationFailed"]

Effects: 13
Error paths: ConfirmationFailedError, InsufficientFundsError, ProviderUnavailableError, RateUnavailableError, TransferRejectedError, ValidationError

Raw effect-analyze output

createSendMoneyWorkflow (generator):
  1. validated = Pipes deps.validateTransfer through:
    Calls deps.validateTransfer — collection
  2. rate = Pipes deps.fetchRate through:
    Calls deps.fetchRate
  3. balance = Pipes deps.getBalance through:
    Calls deps.getBalance
  4. converted = Pipes deps.convertCurrency through:
    Calls deps.convertCurrency
  5. transfer = Pipes deps.executeTransfer through:
    Calls deps.executeTransfer
  6. Pipes deps.sendConfirmation through:
    Calls deps.sendConfirmation

  Error paths: ConfirmationFailedError, InsufficientFundsError, ProviderUnavailableError, RateUnavailableError, TransferRejectedError, ValidationError
  Concurrency: sequential (no parallelism)

[
  {
    "program": "createSendMoneyWorkflow",
    "stats": {
      "totalEffects": 13,
      "parallelCount": 0,
      "raceCount": 0,
      "errorHandlerCount": 0,
      "retryCount": 0,
      "timeoutCount": 0,
      "resourceCount": 0,
      "loopCount": 0,
      "conditionalCount": 0,
      "layerCount": 0,
      "interruptionCount": 0,
      "unknownCount": 0,
      "decisionCount": 0,
      "switchCount": 0,
      "tryCatchCount": 0,
      "terminalCount": 0,
      "opaqueCount": 0
    }
  }
]

Transfer Observability for the narrative around implementation, review, testing, and communication.

Transfer Evolution

Step 1: Validate input

Raw effect-analyze output

Step 2: + Fetch exchange rate

Raw effect-analyze output

Step 3: + Check balance & convert

Raw effect-analyze output

Step 4: + Execute transfer

Raw effect-analyze output

Step 5: + Send confirmation (complete)

Raw effect-analyze output

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