From 89e07dad864b815c4764c9b85da45ae1e1765ad4 Mon Sep 17 00:00:00 2001
From: Sebastian Kosch <sebastian@aldusleaf.org>
Date: Mon, 6 Jul 2020 21:08:56 -0700
Subject: [PATCH] Fix truncation

---
 src/components/DistBuilder.re                 |  2 +-
 .../expressionTree/ExpressionTreeEvaluator.re | 21 ++++++++-----------
 .../expressionTree/ExpressionTypes.re         |  6 ++++++
 src/distPlus/symbolic/SymbolicDist.re         |  5 -----
 src/distPlus/symbolic/SymbolicTypes.re        |  8 ++++++-
 5 files changed, 23 insertions(+), 19 deletions(-)

diff --git a/src/components/DistBuilder.re b/src/components/DistBuilder.re
index 77c64aab..f087a6bf 100644
--- a/src/components/DistBuilder.re
+++ b/src/components/DistBuilder.re
@@ -172,7 +172,7 @@ let make = () => {
       ~onSubmit=({state}) => {None},
       ~initialState={
         //guesstimatorString: "mm(normal(-10, 2), uniform(18, 25), lognormal({mean: 10, stdev: 8}), triangular(31,40,50))",
-        guesstimatorString: "uniform(0, 1) * normal(1, 2) - 1",
+        guesstimatorString: "truncate(normal(100, 60), 50, 100)",
         domainType: "Complete",
         xPoint: "50.0",
         xPoint2: "60.0",
diff --git a/src/distPlus/expressionTree/ExpressionTreeEvaluator.re b/src/distPlus/expressionTree/ExpressionTreeEvaluator.re
index 2325a134..23853db8 100644
--- a/src/distPlus/expressionTree/ExpressionTreeEvaluator.re
+++ b/src/distPlus/expressionTree/ExpressionTreeEvaluator.re
@@ -118,16 +118,17 @@ module PointwiseCombination = {
 };
 
 module Truncate = {
-  let trySimplification = (leftCutoff, rightCutoff, t) => {
+  let trySimplification = (leftCutoff, rightCutoff, t): simplificationResult => {
     switch (leftCutoff, rightCutoff, t) {
-    | (None, None, t) => Ok(t)
+    | (None, None, t) => `Solution(t)
+    | (Some(lc), Some(rc), t) when lc > rc => `Error("Left truncation bound must be smaller than right bound.")
     | (lc, rc, `SymbolicDist(`Uniform(u))) =>
       // just create a new Uniform distribution
       let nu: SymbolicTypes.uniform = u;
       let newLow = max(E.O.default(neg_infinity, lc), nu.low);
       let newHigh = min(E.O.default(infinity, rc), nu.high);
-      Ok(`SymbolicDist(`Uniform({low: newLow, high: newHigh})));
-    | (_, _, t) => Ok(t)
+      `Solution(`SymbolicDist(`Uniform({low: newLow, high: newHigh})));
+    | _ => `NoSolution
     };
   };
 
@@ -135,7 +136,6 @@ module Truncate = {
     // TODO: use named args in renderToShape; if we're lucky we can at least get the tail
     // of a distribution we otherwise wouldn't get at all
     let renderedShape = toLeaf(renderParams, `Render(t));
-
     switch (renderedShape) {
     | Ok(`RenderedDist(rs)) =>
       let truncatedShape =
@@ -157,13 +157,10 @@ module Truncate = {
       : result(node, string) => {
     t
     |> trySimplification(leftCutoff, rightCutoff)
-    |> E.R.bind(
-         _,
-         fun
-         | `SymbolicDist(d) as t => Ok(t)
-         | _ =>
-           truncateAsShape(toLeaf, renderParams, leftCutoff, rightCutoff, t),
-       );
+    |> fun
+       | `Solution(t) => Ok(t)
+       | `Error(e) => Error(e)
+       | `NoSolution => truncateAsShape(toLeaf, renderParams, leftCutoff, rightCutoff, t);
   };
 };
 
diff --git a/src/distPlus/expressionTree/ExpressionTypes.re b/src/distPlus/expressionTree/ExpressionTypes.re
index 06be9967..8b6ece67 100644
--- a/src/distPlus/expressionTree/ExpressionTypes.re
+++ b/src/distPlus/expressionTree/ExpressionTypes.re
@@ -18,3 +18,9 @@ module ExpressionTree = {
     | `FloatFromDist(distToFloatOperation, node)
   ];
 };
+
+type simplificationResult = [
+  | `Solution(ExpressionTree.node)
+  | `Error(string)
+  | `NoSolution
+];
diff --git a/src/distPlus/symbolic/SymbolicDist.re b/src/distPlus/symbolic/SymbolicDist.re
index 96ecf0c1..3b4fb065 100644
--- a/src/distPlus/symbolic/SymbolicDist.re
+++ b/src/distPlus/symbolic/SymbolicDist.re
@@ -274,11 +274,6 @@ module T = {
      can still return an error if there is a serious problem,
      like in the case of a divide by 0.
      */
-  type analyticalSimplificationResult = [
-    | `AnalyticalSolution(SymbolicTypes.symbolicDist)
-    | `Error(string)
-    | `NoSolution
-  ];
   let tryAnalyticalSimplification =
       (
         d1: symbolicDist,
diff --git a/src/distPlus/symbolic/SymbolicTypes.re b/src/distPlus/symbolic/SymbolicTypes.re
index b372a00f..1a5dcf22 100644
--- a/src/distPlus/symbolic/SymbolicTypes.re
+++ b/src/distPlus/symbolic/SymbolicTypes.re
@@ -46,4 +46,10 @@ type symbolicDist = [
   | `Triangular(triangular)
   | `ContinuousShape(continuousShape)
   | `Float(float) // Dirac delta at x. Practically useful only in the context of multimodals.
-];
\ No newline at end of file
+];
+
+type analyticalSimplificationResult = [
+  | `AnalyticalSolution(symbolicDist)
+  | `Error(string)
+  | `NoSolution
+];