exceptions-to-values.7 : flatMap errors

Duncan McGregor · dmcg · commit 442f41316a09 · 2021-07-28T21:55:01.000+01:00
diff --git a/src/main/java/travelator/marketing/HighValueCustomersReport.kt b/src/main/java/travelator/marketing/HighValueCustomersReport.kt
@@ -1,9 +1,6 @@
 package travelator.marketing
 
-import com.natpryce.Failure
-import com.natpryce.Result
-import com.natpryce.Success
-import com.natpryce.recover
+import com.natpryce.*
 
 fun Sequence<String>.toHighValueCustomerReport(
     onErrorLine: (ParseFailure) -> Unit = {}
@@ -34,21 +31,29 @@ private fun Sequence<String>.withoutHeader() = drop(1)
 
 internal fun String.toCustomerData(): Result<CustomerData, ParseFailure> =
     split("\t").let { parts ->
-        if (parts.size < 4)
-            return Failure(NotEnoughFieldsFailure(this))
-        val score = parts[3].toIntOrNull() ?:
-            return Failure(ScoreIsNotAnIntFailure(this))
-        val spend = if (parts.size == 4) 0.0 else parts[4].toDoubleOrNull() ?:
-            return Failure(SpendIsNotADoubleFailure(this))
-        Success(
-            CustomerData(
-                id = parts[0],
-                givenName = parts[1],
-                familyName = parts[2],
-                score = score,
-                spend = spend
-            )
-        )
+        parts
+            .takeUnless { it.size < 4 }
+            .asResultOr { NotEnoughFieldsFailure(this) }
+            .flatMap { parts ->
+                parts[3].toIntOrNull()
+                    .asResultOr { ScoreIsNotAnIntFailure(this) }
+                    .flatMap { score: Int ->
+                        (if (parts.size == 4) 0.0
+                        else parts[4].toDoubleOrNull())
+                            .asResultOr { SpendIsNotADoubleFailure(this) }
+                            .flatMap { spend ->
+                                Success(
+                                    CustomerData(
+                                        id = parts[0],
+                                        givenName = parts[1],
+                                        familyName = parts[2],
+                                        score = score,
+                                        spend = spend
+                                    )
+                                )
+                            }
+                    }
+            }
     }
 
 sealed class ParseFailure(open val line: String)
