Tidy up SimpleJSON.hs

IntersectMBO · Apr 30, 2024 · 4f94b23 · 4f94b23
1 parent 4a29380
commit 4f94b23
Showing 1 changed file with 12 additions and 13 deletions.
diff --git a/plutus-core/plutus-core/src/PlutusCore/Evaluation/Machine/CostingFun/SimpleJSON.hs b/plutus-core/plutus-core/src/PlutusCore/Evaluation/Machine/CostingFun/SimpleJSON.hs
@@ -78,7 +78,7 @@ instance FromJSON Model where
              {- We always have an "arguments" field which is a Value.  Usually it's
                 actually an Object (ie, a map) representing a linear function, but
                 sometimes it contains other data, and in those cases we need to
-                coerce it to an Object (with objOf) to extract the relevant date.
+                coerce it to an Object (with objOf) to extract the relevant data.
                 We could do that once here and rely on laziness to save us in the
                 cases when we don't have an Object, but that looks a bit misleading. -}
              case ty of
@@ -93,18 +93,14 @@ instance FromJSON Model where
                "quadratic_in_y"              -> QuadraticInY          <$> parseJSON args
                "quadratic_in_z"              -> QuadraticInZ          <$> parseJSON args
                "literal_in_y_or_linear_in_z" -> LiteralInYOrLinearInZ <$> parseJSON args
-               "subtracted_sizes" ->
-                  SubtractedSizes       <$> parseJSON args <*> objOf args .: "minimum"
-               "const_above_diagonal" ->
-                 let o = objOf args in ConstAboveDiagonal <$>  o .: "constant" <*> o .: "model"
-               "const_below_diagonal" ->
-                 let o = objOf args in ConstBelowDiagonal <$> o .: "constant" <*> o .: "model"
-               "const_off_diagonal" ->
-                 let o = objOf args in ConstOffDiagonal <$> o .: "constant" <*> o .: "model"
-               -- An adaptor to deal with the old "linear_on_diagonal" tag.  See Note [Backward
-               -- compatibility for costing functions].  We never want to convert back to JSON here,
-               -- so it's OK to forget that we originally got something tagged with
-               -- "linear_on_diagonal".
+               "subtracted_sizes"            -> SubtractedSizes       <$> parseJSON args <*> objOf args .: "minimum"
+               "const_above_diagonal"        -> modelWithConstant ConstAboveDiagonal args
+               "const_below_diagonal"        -> modelWithConstant ConstBelowDiagonal args
+               "const_off_diagonal"          -> modelWithConstant ConstOffDiagonal   args
+               {- An adaptor to deal with the old "linear_on_diagonal" tag.  See Note [Backward
+                  compatibility for costing functions].  We never want to convert back to JSON
+                  here, so it's OK to forget that we originally got something tagged with
+                 "linear_on_diagonal". -}
                "linear_on_diagonal" ->
                  let o = objOf args
                  in do
@@ -119,6 +115,9 @@ instance FromJSON Model where
                      objOf _          =
                       errorWithoutStackTrace "Failed to get Object while parsing \"arguments\""
 
+                     modelWithConstant constr x = constr <$>  o .: "constant" <*> o .: "model"
+                       where o = objOf x
+
 {- | A CPU usage modelling function and a memory usage modelling function bundled
    together -}
 data CpuAndMemoryModel = CpuAndMemoryModel {cpuModel :: Model, memoryModel :: Model}