From b9c8a7e2c711c2bc1ac109330f5b7f1802e6a2e1 Mon Sep 17 00:00:00 2001
From: Quinn Dougherty <quinnd@riseup.net>
Date: Tue, 26 Apr 2022 16:58:36 -0400
Subject: [PATCH] Input validation for cauchy

Value: [0.01 to 0.08]

Sam gets most of the credit
---
 .../rescript/Distributions/SymbolicDist/SymbolicDist.res   | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDist.res b/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDist.res
index 92249eae..997506d9 100644
--- a/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDist.res
+++ b/packages/squiggle-lang/src/rescript/Distributions/SymbolicDist/SymbolicDist.res
@@ -86,9 +86,10 @@ module Exponential = {
 
 module Cauchy = {
   type t = cauchy
-  let make = (local, scale): result<symbolicDist, string> => Ok(
-    #Cauchy({local: local, scale: scale}),
-  )
+  let make = (local, scale): result<symbolicDist, string> =>
+    scale > 0.0
+      ? Ok(#Cauchy({local: local, scale: scale}))
+      : Error("Cauchy distribution scale parameter must larger than 0.")
   let pdf = (x, t: t) => Jstat.Cauchy.pdf(x, t.local, t.scale)
   let cdf = (x, t: t) => Jstat.Cauchy.cdf(x, t.local, t.scale)
   let inv = (p, t: t) => Jstat.Cauchy.inv(p, t.local, t.scale)