Fix bug in the transaction example (#2667)

Co-authored-by: Imran Malic Settuba <46971368+i-walker@users.noreply.github.com> Co-authored-by: Wenkai Yuan <wenkai.yuan@crypto.com>
arrow-kt · Feb 28, 2022 · f7707ac · f7707ac
1 parent 1bed6da
commit f7707ac
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diff --git a/arrow-libs/fx/arrow-fx-stm/src/commonMain/kotlin/arrow/fx/stm/STM.kt b/arrow-libs/fx/arrow-fx-stm/src/commonMain/kotlin/arrow/fx/stm/STM.kt
@@ -55,7 +55,7 @@ import arrow.fx.stm.internal.lookupHamtWithHash
  *
  * fun STM.withdraw(acc: TVar<Int>, amount: Int): Unit {
  *   val current = acc.read()
- *   if (current - amount >= 0) acc.write(current + amount)
+ *   if (current - amount >= 0) acc.write(current - amount)
  *   else throw IllegalStateException("Not enough money in the account!")
  * }
  * //sampleEnd
@@ -112,7 +112,7 @@ import arrow.fx.stm.internal.lookupHamtWithHash
  *
  * fun STM.withdraw(acc: TVar<Int>, amount: Int): Unit {
  *   val current = acc.read()
- *   if (current - amount >= 0) acc.write(current + amount)
+ *   if (current - amount >= 0) acc.write(current - amount)
  *   else retry() // we now retry if there is not enough money in the account
  *   // this can also be achieved by using `check(current - amount >= 0); acc.write(it + amount)`
  * }

diff --git a/arrow-libs/fx/arrow-fx-stm/src/jvmTest/kotlin/examples/example-stm-01.kt b/arrow-libs/fx/arrow-fx-stm/src/jvmTest/kotlin/examples/example-stm-01.kt
@@ -18,7 +18,7 @@ fun STM.deposit(acc: TVar<Int>, amount: Int): Unit {
 
 fun STM.withdraw(acc: TVar<Int>, amount: Int): Unit {
   val current = acc.read()
-  if (current - amount >= 0) acc.write(current + amount)
+  if (current - amount >= 0) acc.write(current - amount)
   else throw IllegalStateException("Not enough money in the account!")
 }
 

diff --git a/arrow-libs/fx/arrow-fx-stm/src/jvmTest/kotlin/examples/example-stm-02.kt b/arrow-libs/fx/arrow-fx-stm/src/jvmTest/kotlin/examples/example-stm-02.kt
@@ -21,7 +21,7 @@ fun STM.deposit(acc: TVar<Int>, amount: Int): Unit {
 
 fun STM.withdraw(acc: TVar<Int>, amount: Int): Unit {
   val current = acc.read()
-  if (current - amount >= 0) acc.write(current + amount)
+  if (current - amount >= 0) acc.write(current - amount)
   else retry() // we now retry if there is not enough money in the account
   // this can also be achieved by using `check(current - amount >= 0); acc.write(it + amount)`
 }