From 958c187e826d48ca845459f1fc3298851efb6be8 Mon Sep 17 00:00:00 2001
From: Vyacheslav Matyukhin <me@berekuk.ru>
Date: Sat, 4 Jun 2022 23:38:16 +0300
Subject: [PATCH] Various components cleanups

- coding style (let -> const, etc.)
- avoid double typing of component props, it's not necessary
- consistent non-default exports everywhere (except for
  SquigglePlayground since I'm not 100% sure it's not used somewhere
  else)
- extract common components in SquigglePlayground to avoid copy-paste
- other minor improvements
---
 packages/components/src/components/Alert.tsx  |  58 ++-
 .../components/src/components/CodeEditor.tsx  |   5 +-
 .../src/components/DistributionChart.tsx      | 166 +++---
 .../src/components/FunctionChart.tsx          |   2 +-
 .../src/components/FunctionChart1Dist.tsx     |   8 +-
 .../components/src/components/JsonEditor.tsx  |  10 +-
 .../src/components/NumberShower.tsx           |  13 +-
 .../src/components/SquiggleChart.tsx          | 102 ++--
 .../src/components/SquiggleEditor.tsx         |  20 +-
 .../src/components/SquigglePlayground.tsx     | 485 +++++++++---------
 packages/components/src/index.ts              |   4 +-
 .../src/stories/SquiggleChart.stories.js.map  |   1 -
 12 files changed, 429 insertions(+), 445 deletions(-)
 delete mode 100644 packages/components/src/stories/SquiggleChart.stories.js.map

diff --git a/packages/components/src/components/Alert.tsx b/packages/components/src/components/Alert.tsx
index 4e1dc646..590b1cca 100644
--- a/packages/components/src/components/Alert.tsx
+++ b/packages/components/src/components/Alert.tsx
@@ -10,23 +10,32 @@ export const Alert: React.FC<{
   backgroundColor: string;
   headingColor: string;
   bodyColor: string;
-  icon: React.ReactNode;
-  children: React.ReactNode;
+  icon: (props: React.ComponentProps<"svg">) => JSX.Element;
+  iconColor: string;
+  children?: React.ReactNode;
 }> = ({
   heading = "Error",
   backgroundColor,
   headingColor,
   bodyColor,
-  icon,
+  icon: Icon,
+  iconColor,
   children,
 }) => {
   return (
     <div className={`rounded-md p-4 ${backgroundColor}`}>
       <div className="flex">
-        <div className="flex-shrink-0">{icon}</div>
+        <Icon
+          className={`h-5 w-5 flex-shrink-0 ${iconColor}`}
+          aria-hidden="true"
+        />
         <div className="ml-3">
-          <h3 className={`text-sm font-medium ${headingColor}`}>{heading}</h3>
-          <div className={`mt-2 text-sm ${bodyColor}`}>{children}</div>
+          <header className={`text-sm font-medium ${headingColor}`}>
+            {heading}
+          </header>
+          {children && React.Children.count(children) ? (
+            <div className={`mt-2 text-sm ${bodyColor}`}>{children}</div>
+          ) : null}
         </div>
       </div>
     </div>
@@ -35,49 +44,42 @@ export const Alert: React.FC<{
 
 export const ErrorAlert: React.FC<{
   heading: string;
-  children: React.ReactNode;
-}> = ({ heading = "Error", children }) => (
+  children?: React.ReactNode;
+}> = (props) => (
   <Alert
-    heading={heading}
-    children={children}
+    {...props}
     backgroundColor="bg-red-100"
     headingColor="text-red-800"
     bodyColor="text-red-700"
-    icon={<XCircleIcon className="h-5 w-5 text-red-400" aria-hidden="true" />}
+    icon={XCircleIcon}
+    iconColor="text-red-400"
   />
 );
 
 export const MessageAlert: React.FC<{
   heading: string;
-  children: React.ReactNode;
-}> = ({ heading = "Error", children }) => (
+  children?: React.ReactNode;
+}> = (props) => (
   <Alert
-    heading={heading}
-    children={children}
+    {...props}
     backgroundColor="bg-slate-100"
     headingColor="text-slate-700"
     bodyColor="text-slate-700"
-    icon={
-      <InformationCircleIcon
-        className="h-5 w-5 text-slate-400"
-        aria-hidden="true"
-      />
-    }
+    icon={InformationCircleIcon}
+    iconColor="text-slate-400"
   />
 );
 
 export const SuccessAlert: React.FC<{
   heading: string;
-  children: React.ReactNode;
-}> = ({ heading = "Error", children }) => (
+  children?: React.ReactNode;
+}> = (props) => (
   <Alert
-    heading={heading}
-    children={children}
+    {...props}
     backgroundColor="bg-green-50"
     headingColor="text-green-800"
     bodyColor="text-green-700"
-    icon={
-      <CheckCircleIcon className="h-5 w-5 text-green-400" aria-hidden="true" />
-    }
+    icon={CheckCircleIcon}
+    iconColor="text-green-400"
   />
 );
diff --git a/packages/components/src/components/CodeEditor.tsx b/packages/components/src/components/CodeEditor.tsx
index 473afd93..5d9340b8 100644
--- a/packages/components/src/components/CodeEditor.tsx
+++ b/packages/components/src/components/CodeEditor.tsx
@@ -14,13 +14,13 @@ interface CodeEditorProps {
   showGutter?: boolean;
 }
 
-export let CodeEditor: FC<CodeEditorProps> = ({
+export const CodeEditor: FC<CodeEditorProps> = ({
   value,
   onChange,
   oneLine = false,
   showGutter = false,
   height,
-}: CodeEditorProps) => {
+}) => {
   let lineCount = value.split("\n").length;
   let id = _.uniqueId();
   return (
@@ -48,4 +48,3 @@ export let CodeEditor: FC<CodeEditorProps> = ({
     />
   );
 };
-export default CodeEditor;
diff --git a/packages/components/src/components/DistributionChart.tsx b/packages/components/src/components/DistributionChart.tsx
index 7dcb3bb1..18dd2a3e 100644
--- a/packages/components/src/components/DistributionChart.tsx
+++ b/packages/components/src/components/DistributionChart.tsx
@@ -1,5 +1,4 @@
 import * as React from "react";
-import _ from "lodash";
 import {
   Distribution,
   result,
@@ -34,71 +33,64 @@ export const DistributionChart: React.FC<DistributionChartProps> = ({
   showSummary,
   width,
   showControls = false,
-}: DistributionChartProps) => {
-  let [isLogX, setLogX] = React.useState(false);
-  let [isExpY, setExpY] = React.useState(false);
-  let shape = distribution.pointSet();
-  const [sized, _] = useSize((size) => {
-    if (shape.tag === "Ok") {
-      let massBelow0 =
-        shape.value.continuous.some((x) => x.x <= 0) ||
-        shape.value.discrete.some((x) => x.x <= 0);
-      let spec = buildVegaSpec(isLogX, isExpY);
-      let widthProp = width ? width : size.width;
-      if (widthProp < 20) {
-        console.warn(
-          `Width of Distribution is set to ${widthProp}, which is too small`
-        );
-        widthProp = 20;
-      }
-
-      // Check whether we should disable the checkbox
-      var logCheckbox = (
-        <CheckBox label="Log X scale" value={isLogX} onChange={setLogX} />
-      );
-      if (massBelow0) {
-        logCheckbox = (
-          <CheckBox
-            label="Log X scale"
-            value={isLogX}
-            onChange={setLogX}
-            disabled={true}
-            tooltip={
-              "Your distribution has mass lower than or equal to 0. Log only works on strictly positive values."
-            }
-          />
-        );
-      }
-
-      var result = (
-        <div style={{ width: widthProp + "px" }}>
-          <Vega
-            spec={spec}
-            data={{ con: shape.value.continuous, dis: shape.value.discrete }}
-            width={widthProp - 10}
-            height={height}
-            actions={false}
-          />
-          <div className="flex justify-center">
-            {showSummary && <SummaryTable distribution={distribution} />}
-          </div>
-          {showControls && (
-            <div>
-              {logCheckbox}
-              <CheckBox label="Exp Y scale" value={isExpY} onChange={setExpY} />
-            </div>
-          )}
-        </div>
-      );
-    } else {
-      var result = (
+}) => {
+  const [isLogX, setLogX] = React.useState(false);
+  const [isExpY, setExpY] = React.useState(false);
+  const shape = distribution.pointSet();
+  const [sized] = useSize((size) => {
+    if (shape.tag === "Error") {
+      return (
         <ErrorAlert heading="Distribution Error">
           {distributionErrorToString(shape.value)}
         </ErrorAlert>
       );
     }
 
-    return result;
+    const massBelow0 =
+      shape.value.continuous.some((x) => x.x <= 0) ||
+      shape.value.discrete.some((x) => x.x <= 0);
+    const spec = buildVegaSpec(isLogX, isExpY);
+
+    let widthProp = width ? width : size.width;
+    if (widthProp < 20) {
+      console.warn(
+        `Width of Distribution is set to ${widthProp}, which is too small`
+      );
+      widthProp = 20;
+    }
+
+    return (
+      <div style={{ width: widthProp }}>
+        <Vega
+          spec={spec}
+          data={{ con: shape.value.continuous, dis: shape.value.discrete }}
+          width={widthProp - 10}
+          height={height}
+          actions={false}
+        />
+        <div className="flex justify-center">
+          {showSummary && <SummaryTable distribution={distribution} />}
+        </div>
+        {showControls && (
+          <div>
+            <CheckBox
+              label="Log X scale"
+              value={isLogX}
+              onChange={setLogX}
+              // Check whether we should disable the checkbox
+              {...(massBelow0
+                ? {
+                    disabled: true,
+                    tooltip:
+                      "Your distribution has mass lower than or equal to 0. Log only works on strictly positive values.",
+                  }
+                : {})}
+            />
+            <CheckBox label="Exp Y scale" value={isExpY} onChange={setExpY} />
+          </div>
+        )}
+      </div>
+    );
   });
   return sized;
 };
@@ -121,13 +113,13 @@ interface CheckBoxProps {
   tooltip?: string;
 }
 
-export const CheckBox = ({
+export const CheckBox: React.FC<CheckBoxProps> = ({
   label,
   onChange,
   value,
   disabled = false,
   tooltip,
-}: CheckBoxProps) => {
+}) => {
   return (
     <span title={tooltip}>
       <input
@@ -141,22 +133,35 @@ export const CheckBox = ({
   );
 };
 
+const TableHeadCell: React.FC<{ children: React.ReactNode }> = ({
+  children,
+}) => (
+  <th className="border border-slate-200 bg-slate-50 py-1 px-2 text-slate-500 font-semibold">
+    {children}
+  </th>
+);
+
+const Cell: React.FC<{ children: React.ReactNode }> = ({ children }) => (
+  <td className="border border-slate-200 py-1 px-2 text-slate-900">
+    {children}
+  </td>
+);
+
 type SummaryTableProps = {
   distribution: Distribution;
 };
 
-const SummaryTable: React.FC<SummaryTableProps> = ({
-  distribution,
-}: SummaryTableProps) => {
-  let mean = distribution.mean();
-  let p5 = distribution.inv(0.05);
-  let p10 = distribution.inv(0.1);
-  let p25 = distribution.inv(0.25);
-  let p50 = distribution.inv(0.5);
-  let p75 = distribution.inv(0.75);
-  let p90 = distribution.inv(0.9);
-  let p95 = distribution.inv(0.95);
-  let unwrapResult = (
+const SummaryTable: React.FC<SummaryTableProps> = ({ distribution }) => {
+  const mean = distribution.mean();
+  const p5 = distribution.inv(0.05);
+  const p10 = distribution.inv(0.1);
+  const p25 = distribution.inv(0.25);
+  const p50 = distribution.inv(0.5);
+  const p75 = distribution.inv(0.75);
+  const p90 = distribution.inv(0.9);
+  const p95 = distribution.inv(0.95);
+
+  const unwrapResult = (
     x: result<number, distributionError>
   ): React.ReactNode => {
     if (x.tag === "Ok") {
@@ -170,19 +175,6 @@ const SummaryTable: React.FC<SummaryTableProps> = ({
     }
   };
 
-  let TableHeadCell: React.FC<{ children: React.ReactNode }> = ({
-    children,
-  }) => (
-    <th className="border border-slate-200 bg-slate-50 py-1 px-2 text-slate-500 font-semibold">
-      {children}
-    </th>
-  );
-  let Cell: React.FC<{ children: React.ReactNode }> = ({ children }) => (
-    <td className="border border-slate-200 py-1 px-2 text-slate-900 ">
-      {children}
-    </td>
-  );
-
   return (
     <table className="border border-collapse border-slate-400">
       <thead className="bg-slate-50">
diff --git a/packages/components/src/components/FunctionChart.tsx b/packages/components/src/components/FunctionChart.tsx
index 553b9b4e..7e8749a3 100644
--- a/packages/components/src/components/FunctionChart.tsx
+++ b/packages/components/src/components/FunctionChart.tsx
@@ -22,7 +22,7 @@ export const FunctionChart: React.FC<FunctionChartProps> = ({
   chartSettings,
   environment,
   height,
-}: FunctionChartProps) => {
+}) => {
   if (fn.parameters.length > 1) {
     return (
       <MessageAlert heading="Function Display Not Supported">
diff --git a/packages/components/src/components/FunctionChart1Dist.tsx b/packages/components/src/components/FunctionChart1Dist.tsx
index 28da7411..6c8b2766 100644
--- a/packages/components/src/components/FunctionChart1Dist.tsx
+++ b/packages/components/src/components/FunctionChart1Dist.tsx
@@ -151,7 +151,7 @@ export const FunctionChart1Dist: React.FC<FunctionChart1DistProps> = ({
   chartSettings,
   environment,
   height,
-}: FunctionChart1DistProps) => {
+}) => {
   let [mouseOverlay, setMouseOverlay] = React.useState(0);
   function handleHover(_name: string, value: unknown) {
     setMouseOverlay(value as number);
@@ -170,16 +170,14 @@ export const FunctionChart1Dist: React.FC<FunctionChart1DistProps> = ({
         },
       };
   let showChart =
-    mouseItem.tag === "Ok" && mouseItem.value.tag == "distribution" ? (
+    mouseItem.tag === "Ok" && mouseItem.value.tag === "distribution" ? (
       <DistributionChart
         distribution={mouseItem.value.value}
         width={400}
         height={50}
         showSummary={false}
       />
-    ) : (
-      <></>
-    );
+    ) : null;
 
   let getPercentilesMemoized = React.useMemo(
     () => getPercentiles({ chartSettings, fn, environment }),
diff --git a/packages/components/src/components/JsonEditor.tsx b/packages/components/src/components/JsonEditor.tsx
index c81debf4..a0214d80 100644
--- a/packages/components/src/components/JsonEditor.tsx
+++ b/packages/components/src/components/JsonEditor.tsx
@@ -14,15 +14,15 @@ interface CodeEditorProps {
   showGutter?: boolean;
 }
 
-export let JsonEditor: FC<CodeEditorProps> = ({
+export const JsonEditor: FC<CodeEditorProps> = ({
   value,
   onChange,
   oneLine = false,
   showGutter = false,
   height,
-}: CodeEditorProps) => {
-  let lineCount = value.split("\n").length;
-  let id = _.uniqueId();
+}) => {
+  const lineCount = value.split("\n").length;
+  const id = _.uniqueId();
   return (
     <AceEditor
       value={value}
@@ -47,5 +47,3 @@ export let JsonEditor: FC<CodeEditorProps> = ({
     />
   );
 };
-
-export default JsonEditor;
diff --git a/packages/components/src/components/NumberShower.tsx b/packages/components/src/components/NumberShower.tsx
index 8d3ddae9..601a58d3 100644
--- a/packages/components/src/components/NumberShower.tsx
+++ b/packages/components/src/components/NumberShower.tsx
@@ -1,5 +1,4 @@
 import * as React from "react";
-import _ from "lodash";
 
 const orderOfMagnitudeNum = (n: number) => {
   return Math.pow(10, n);
@@ -74,25 +73,23 @@ export interface NumberShowerProps {
   precision?: number;
 }
 
-export let NumberShower: React.FC<NumberShowerProps> = ({
+export const NumberShower: React.FC<NumberShowerProps> = ({
   number,
   precision = 2,
-}: NumberShowerProps) => {
-  let numberWithPresentation = numberShow(number, precision);
+}) => {
+  const numberWithPresentation = numberShow(number, precision);
   return (
     <span>
       {numberWithPresentation.value}
       {numberWithPresentation.symbol}
       {numberWithPresentation.power ? (
         <span>
-          {"\u00b710"}
+          {"\u00b7" /* dot symbol */}10
           <span style={{ fontSize: "0.6em", verticalAlign: "super" }}>
             {numberWithPresentation.power}
           </span>
         </span>
-      ) : (
-        <></>
-      )}
+      ) : null}
     </span>
   );
 };
diff --git a/packages/components/src/components/SquiggleChart.tsx b/packages/components/src/components/SquiggleChart.tsx
index 2ec31bae..8bedd265 100644
--- a/packages/components/src/components/SquiggleChart.tsx
+++ b/packages/components/src/components/SquiggleChart.tsx
@@ -1,5 +1,4 @@
 import * as React from "react";
-import _ from "lodash";
 import {
   run,
   errorValueToString,
@@ -28,6 +27,7 @@ function getRange<a>(x: declaration<a>) {
     }
   }
 }
+
 function getChartSettings<a>(x: declaration<a>): FunctionChartSettings {
   let range = getRange(x);
   let min = range.floats ? range.floats.min : 0;
@@ -49,12 +49,12 @@ export const VariableBox: React.FC<VariableBoxProps> = ({
   heading = "Error",
   children,
   showTypes = false,
-}: VariableBoxProps) => {
+}) => {
   if (showTypes) {
     return (
       <div className="bg-white border border-grey-200 m-2">
         <div className="border-b border-grey-200 p-3">
-          <h3 className="font-mono">{heading}</h3>
+          <header className="font-mono">{heading}</header>
         </div>
         <div className="p-3">{children}</div>
       </div>
@@ -90,7 +90,7 @@ const SquiggleItem: React.FC<SquiggleItemProps> = ({
   showControls = false,
   chartSettings,
   environment,
-}: SquiggleItemProps) => {
+}) => {
   switch (expression.tag) {
     case "number":
       return (
@@ -108,12 +108,8 @@ const SquiggleItem: React.FC<SquiggleItemProps> = ({
           showTypes={showTypes}
         >
           {distType === "Symbolic" && showTypes ? (
-            <>
-              <div>{expression.value.toString()}</div>
-            </>
-          ) : (
-            <></>
-          )}
+            <div>{expression.value.toString()}</div>
+          ) : null}
           <DistributionChart
             distribution={expression.value}
             height={height}
@@ -157,11 +153,11 @@ const SquiggleItem: React.FC<SquiggleItemProps> = ({
       return (
         <VariableBox heading="Array" showTypes={showTypes}>
           {expression.value.map((r, i) => (
-            <div key={i} className="flex flex-row pt-1">
+            <div key={i} className="flex pt-1">
               <div className="flex-none bg-slate-100 rounded-sm px-1">
-                <h3 className="text-slate-400 font-mono">{i}</h3>
+                <header className="text-slate-400 font-mono">{i}</header>
               </div>
-              <div className="px-2 mb-2 grow ">
+              <div className="px-2 mb-2 grow">
                 <SquiggleItem
                   key={i}
                   expression={r}
@@ -181,25 +177,27 @@ const SquiggleItem: React.FC<SquiggleItemProps> = ({
     case "record":
       return (
         <VariableBox heading="Record" showTypes={showTypes}>
-          {Object.entries(expression.value).map(([key, r]) => (
-            <div key={key} className="flex flex-row pt-1">
-              <div className="flex-none pr-2">
-                <h3 className="text-slate-500 font-mono">{key}:</h3>
+          <div className="space-y-3">
+            {Object.entries(expression.value).map(([key, r]) => (
+              <div key={key} className="flex space-x-2">
+                <div className="flex-none">
+                  <header className="text-slate-500 font-mono">{key}:</header>
+                </div>
+                <div className="px-2 grow bg-gray-50 border border-gray-100 rounded-sm">
+                  <SquiggleItem
+                    expression={r}
+                    width={width !== undefined ? width - 20 : width}
+                    height={height / 3}
+                    showTypes={showTypes}
+                    showSummary={showSummary}
+                    showControls={showControls}
+                    chartSettings={chartSettings}
+                    environment={environment}
+                  />
+                </div>
               </div>
-              <div className="pl-2 pr-2 mb-2 grow bg-gray-50 border border-gray-100 rounded-sm">
-                <SquiggleItem
-                  expression={r}
-                  width={width !== undefined ? width - 20 : width}
-                  height={height / 3}
-                  showTypes={showTypes}
-                  showSummary={showSummary}
-                  showControls={showControls}
-                  chartSettings={chartSettings}
-                  environment={environment}
-                />
-              </div>
-            </div>
-          ))}
+            ))}
+          </div>
         </VariableBox>
       );
     case "arraystring":
@@ -285,7 +283,7 @@ export interface SquiggleChartProps {
   showControls?: boolean;
 }
 
-let defaultChartSettings = { start: 0, stop: 10, count: 20 };
+const defaultChartSettings = { start: 0, stop: 10, count: 20 };
 
 export const SquiggleChart: React.FC<SquiggleChartProps> = ({
   squiggleString = "",
@@ -299,31 +297,29 @@ export const SquiggleChart: React.FC<SquiggleChartProps> = ({
   showTypes = false,
   showControls = false,
   chartSettings = defaultChartSettings,
-}: SquiggleChartProps) => {
+}) => {
   let expressionResult = run(squiggleString, bindings, environment, jsImports);
-  let e = environment ? environment : defaultEnvironment;
-  let internal: JSX.Element;
-  if (expressionResult.tag === "Ok") {
-    let expression = expressionResult.value;
-    onChange(expression);
-    internal = (
-      <SquiggleItem
-        expression={expression}
-        width={width}
-        height={height}
-        showSummary={showSummary}
-        showTypes={showTypes}
-        showControls={showControls}
-        chartSettings={chartSettings}
-        environment={e}
-      />
-    );
-  } else {
-    internal = (
+  if (expressionResult.tag !== "Ok") {
+    return (
       <ErrorAlert heading={"Parse Error"}>
         {errorValueToString(expressionResult.value)}
       </ErrorAlert>
     );
   }
-  return internal;
+
+  let e = environment ?? defaultEnvironment;
+  let expression = expressionResult.value;
+  onChange(expression);
+  return (
+    <SquiggleItem
+      expression={expression}
+      width={width}
+      height={height}
+      showSummary={showSummary}
+      showTypes={showTypes}
+      showControls={showControls}
+      chartSettings={chartSettings}
+      environment={e}
+    />
+  );
 };
diff --git a/packages/components/src/components/SquiggleEditor.tsx b/packages/components/src/components/SquiggleEditor.tsx
index bd90c6b1..e35de4f5 100644
--- a/packages/components/src/components/SquiggleEditor.tsx
+++ b/packages/components/src/components/SquiggleEditor.tsx
@@ -57,8 +57,8 @@ export let SquiggleEditor: React.FC<SquiggleEditorProps> = ({
   showControls = false,
   showSummary = false,
 }: SquiggleEditorProps) => {
-  let [expression, setExpression] = React.useState(initialSquiggleString);
-  let chartSettings = {
+  const [expression, setExpression] = React.useState(initialSquiggleString);
+  const chartSettings = {
     start: diagramStart,
     stop: diagramStop,
     count: diagramCount,
@@ -150,17 +150,17 @@ export let SquigglePartial: React.FC<SquigglePartialProps> = ({
   environment,
   jsImports = defaultImports,
 }: SquigglePartialProps) => {
-  let [expression, setExpression] = React.useState(initialSquiggleString);
-  let [error, setError] = React.useState<string | null>(null);
+  const [expression, setExpression] = React.useState(initialSquiggleString);
+  const [error, setError] = React.useState<string | null>(null);
 
-  let runSquiggleAndUpdateBindings = () => {
-    let squiggleResult = runPartial(
+  const runSquiggleAndUpdateBindings = () => {
+    const squiggleResult = runPartial(
       expression,
       bindings,
       environment,
       jsImports
     );
-    if (squiggleResult.tag == "Ok") {
+    if (squiggleResult.tag === "Ok") {
       if (onChange) onChange(squiggleResult.value);
       setError(null);
     } else {
@@ -181,11 +181,7 @@ export let SquigglePartial: React.FC<SquigglePartialProps> = ({
           height={20}
         />
       </div>
-      {error !== null ? (
-        <ErrorAlert heading="Error">{error}</ErrorAlert>
-      ) : (
-        <></>
-      )}
+      {error !== null ? <ErrorAlert heading="Error">{error}</ErrorAlert> : null}
     </div>
   );
 };
diff --git a/packages/components/src/components/SquigglePlayground.tsx b/packages/components/src/components/SquigglePlayground.tsx
index cff11825..e0214af6 100644
--- a/packages/components/src/components/SquigglePlayground.tsx
+++ b/packages/components/src/components/SquigglePlayground.tsx
@@ -1,19 +1,21 @@
-import _ from "lodash";
-import React, { FC, ReactElement, useState } from "react";
+import React, { FC, Fragment, useState } from "react";
 import ReactDOM from "react-dom";
-import { SquiggleChart } from "./SquiggleChart";
-import CodeEditor from "./CodeEditor";
-import JsonEditor from "./JsonEditor";
-import { useForm, useWatch } from "react-hook-form";
+import { Path, useForm, UseFormRegister, useWatch } from "react-hook-form";
 import * as yup from "yup";
 import { yupResolver } from "@hookform/resolvers/yup";
-import { defaultBindings, environment } from "@quri/squiggle-lang";
 import { Tab } from "@headlessui/react";
-import { CodeIcon } from "@heroicons/react/solid";
-import { CogIcon } from "@heroicons/react/solid";
-import { ChartSquareBarIcon } from "@heroicons/react/solid";
-import { CurrencyDollarIcon } from "@heroicons/react/solid";
-import { Fragment } from "react";
+import {
+  ChartSquareBarIcon,
+  CodeIcon,
+  CogIcon,
+  CurrencyDollarIcon,
+} from "@heroicons/react/solid";
+
+import { defaultBindings, environment } from "@quri/squiggle-lang";
+
+import { SquiggleChart } from "./SquiggleChart";
+import { CodeEditor } from "./CodeEditor";
+import { JsonEditor } from "./JsonEditor";
 import { ErrorAlert, SuccessAlert } from "./Alert";
 
 interface PlaygroundProps {
@@ -85,49 +87,20 @@ const schema = yup
   })
   .required();
 
-type InputProps = {
-  label: string;
-  children: ReactElement;
-};
-
-const InputItem: React.FC<InputProps> = ({ label, children }) => (
-  <div className="col-span-4">
-    <label className="block text-sm font-medium text-gray-600">{label}</label>
-    <div className="mt-1">{children}</div>
-  </div>
-);
-
-let numberStyle =
-  "max-w-lg block w-full shadow-sm focus:ring-indigo-500 focus:border-indigo-500 sm:max-w-xs sm:text-sm border-gray-300 rounded-md";
-
 function classNames(...classes: string[]) {
   return classes.filter(Boolean).join(" ");
 }
 
 type StyledTabProps = {
   name: string;
-  iconName: string;
+  icon: (props: React.ComponentProps<"svg">) => JSX.Element;
 };
 
-const StyledTab: React.FC<StyledTabProps> = ({ name, iconName }) => {
-  let iconStyle = (isSelected: boolean) =>
-    classNames(
-      "-ml-0.5 mr-2 h-4 w-4 ",
-      isSelected ? "text-slate-500" : "text-gray-400 group-hover:text-gray-900"
-    );
-
-  let icon = (selected: boolean) =>
-    ({
-      code: <CodeIcon className={iconStyle(selected)} />,
-      cog: <CogIcon className={iconStyle(selected)} />,
-      squareBar: <ChartSquareBarIcon className={iconStyle(selected)} />,
-      dollar: <CurrencyDollarIcon className={iconStyle(selected)} />,
-    }[iconName]);
-
+const StyledTab: React.FC<StyledTabProps> = ({ name, icon: Icon }) => {
   return (
     <Tab key={name} as={Fragment}>
       {({ selected }) => (
-        <button className="flex rounded-md focus:outline-none focus-visible:ring-offset-gray-100 ">
+        <button className="group flex rounded-md focus:outline-none focus-visible:ring-offset-gray-100">
           <span
             className={classNames(
               "p-1 pl-2.5 pr-3.5 rounded-md flex items-center text-sm font-medium",
@@ -136,7 +109,14 @@ const StyledTab: React.FC<StyledTabProps> = ({ name, iconName }) => {
                 : ""
             )}
           >
-            {icon(selected)}
+            <Icon
+              className={classNames(
+                "-ml-0.5 mr-2 h-4 w-4",
+                selected
+                  ? "text-slate-500"
+                  : "text-gray-400 group-hover:text-gray-900"
+              )}
+            />
             <span
               className={
                 selected
@@ -153,17 +133,77 @@ const StyledTab: React.FC<StyledTabProps> = ({ name, iconName }) => {
   );
 };
 
-let SquigglePlayground: FC<PlaygroundProps> = ({
+const HeadedSection: FC<{ title: string; children: React.ReactNode }> = ({
+  title,
+  children,
+}) => (
+  <div>
+    <header className="text-lg leading-6 font-medium text-gray-900">
+      {title}
+    </header>
+    <div className="mt-4">{children}</div>
+  </div>
+);
+
+const Text: FC<{ children: React.ReactNode }> = ({ children }) => (
+  <p className="text-sm text-gray-500">{children}</p>
+);
+
+function InputItem<T>({
+  name,
+  label,
+  type,
+  register,
+}: {
+  name: Path<T>;
+  label: string;
+  type: "number";
+  register: UseFormRegister<T>;
+}) {
+  const numberStyle =
+    "max-w-lg block w-full shadow-sm focus:ring-indigo-500 focus:border-indigo-500 sm:max-w-xs sm:text-sm border-gray-300 rounded-md";
+
+  return (
+    <label className="block">
+      <div className="text-sm font-medium text-gray-600 mb-1">{label}</div>
+      <input type={type} {...register(name)} className={numberStyle} />
+    </label>
+  );
+}
+
+function Checkbox<T>({
+  name,
+  label,
+  register,
+}: {
+  name: Path<T>;
+  label: string;
+  register: UseFormRegister<T>;
+}) {
+  return (
+    <label className="flex items-center">
+      <input
+        type="checkbox"
+        {...register(name)}
+        className="focus:ring-indigo-500 h-4 w-4 text-indigo-600 border-gray-300 rounded"
+      />
+      {/* Clicking on the div makes the checkbox lose focus while mouse button is pressed, leading to annoying blinking; I couldn't figure out how to fix this. */}
+      <div className="ml-3 text-sm font-medium text-gray-700">{label}</div>
+    </label>
+  );
+}
+
+const SquigglePlayground: FC<PlaygroundProps> = ({
   initialSquiggleString = "",
   height = 500,
   showTypes = false,
   showControls = false,
   showSummary = false,
-}: PlaygroundProps) => {
-  let [squiggleString, setSquiggleString] = useState(initialSquiggleString);
-  let [importString, setImportString] = useState("{}");
-  let [imports, setImports] = useState({});
-  let [importsAreValid, setImportsAreValid] = useState(true);
+}) => {
+  const [squiggleString, setSquiggleString] = useState(initialSquiggleString);
+  const [importString, setImportString] = useState("{}");
+  const [imports, setImports] = useState({});
+  const [importsAreValid, setImportsAreValid] = useState(true);
   const { register, control } = useForm({
     resolver: yupResolver(schema),
     defaultValues: {
@@ -183,16 +223,16 @@ let SquigglePlayground: FC<PlaygroundProps> = ({
   const vars = useWatch({
     control,
   });
-  let chartSettings = {
+  const chartSettings = {
     start: Number(vars.diagramStart),
     stop: Number(vars.diagramStop),
     count: Number(vars.diagramCount),
   };
-  let env: environment = {
+  const env: environment = {
     sampleCount: Number(vars.sampleCount),
     xyPointLength: Number(vars.xyPointLength),
   };
-  let getChangeJson = (r: string) => {
+  const getChangeJson = (r: string) => {
     setImportString(r);
     try {
       setImports(JSON.parse(r));
@@ -202,217 +242,184 @@ let SquigglePlayground: FC<PlaygroundProps> = ({
     }
   };
 
-  let samplingSettings = (
+  const samplingSettings = (
     <div className="space-y-6 p-3 max-w-xl">
-      <InputItem label="Sample Count">
-        <>
-          <input
-            type="number"
-            {...register("sampleCount")}
-            className={numberStyle}
-          />
-          <p className="mt-2 text-sm text-gray-500">
+      <div>
+        <InputItem
+          name="sampleCount"
+          type="number"
+          label="Sample Count"
+          register={register}
+        />
+        <div className="mt-2">
+          <Text>
             How many samples to use for Monte Carlo simulations. This can
             occasionally be overridden by specific Squiggle programs.
-          </p>
-        </>
-      </InputItem>
-      <InputItem label="Coordinate Count (For PointSet Shapes)">
-        <>
-          <input
-            type="number"
-            {...register("xyPointLength")}
-            className={numberStyle}
-          />
-          <p className="mt-2 text-sm text-gray-500">
+          </Text>
+        </div>
+      </div>
+      <div>
+        <InputItem
+          name="xyPointLength"
+          type="number"
+          register={register}
+          label="Coordinate Count (For PointSet Shapes)"
+        />
+        <div className="mt-2">
+          <Text>
             When distributions are converted into PointSet shapes, we need to
             know how many coordinates to use.
-          </p>
-        </>
-      </InputItem>
+          </Text>
+        </div>
+      </div>
     </div>
   );
 
-  let viewSettings = (
+  const viewSettings = (
     <div className="space-y-6 p-3 divide-y divide-gray-200 max-w-xl">
-      <div className="space-y-2">
-        <h3 className="text-lg leading-6 font-medium text-gray-900 pb-2">
-          General Display Settings
-        </h3>
-        <InputItem label="Chart Height (in pixels)">
-          <input
+      <HeadedSection title="General Display Settings">
+        <div className="space-y-4">
+          <InputItem
+            name="chartHeight"
             type="number"
-            {...register("chartHeight")}
-            className={numberStyle}
+            register={register}
+            label="Chart Height (in pixels)"
           />
-        </InputItem>
-        <div className="relative flex items-start pt-3">
-          <div className="flex items-center h-5">
-            <input
-              type="checkbox"
-              {...register("showTypes")}
-              className="focus:ring-indigo-500 h-4 w-4 text-indigo-600 border-gray-300 rounded"
+          <Checkbox
+            name="showTypes"
+            register={register}
+            label="Show information about displayed types"
+          />
+        </div>
+      </HeadedSection>
+
+      <div className="pt-8">
+        <HeadedSection title="Distribution Display Settings">
+          <div className="space-y-2">
+            <Checkbox
+              register={register}
+              name="showControls"
+              label="Show toggles to adjust scale of x and y axes"
+            />
+            <Checkbox
+              register={register}
+              name="showSummary"
+              label="Show summary statistics"
             />
           </div>
-          <div className="ml-3 text-sm">
-            <label className="font-medium text-gray-700">
-              Show information about displayed types.
-            </label>
-          </div>
-        </div>
+        </HeadedSection>
       </div>
 
-      <div className="space-y-2 pt-8">
-        <h3 className="text-lg leading-6 font-medium text-gray-900 pb-2">
-          Distribution Display Settings
-        </h3>
-
-        <div className="relative flex items-start">
-          <div className="flex items-center h-5">
-            <input
-              type="checkbox"
-              {...register("showControls")}
-              className="focus:ring-indigo-500 h-4 w-4 text-indigo-600 border-gray-300 rounded"
-            />
+      <div className="pt-8">
+        <HeadedSection title="Function Display Settings">
+          <div className="space-y-6">
+            <Text>
+              When displaying functions of single variables that return numbers
+              or distributions, we need to use defaults for the x-axis. We need
+              to select a minimum and maximum value of x to sample, and a number
+              n of the number of points to sample.
+            </Text>
+            <div className="space-y-4">
+              <InputItem
+                type="number"
+                name="diagramStart"
+                register={register}
+                label="Min X Value"
+              />
+              <InputItem
+                type="number"
+                name="diagramStop"
+                register={register}
+                label="Max X Value"
+              />
+              <InputItem
+                type="number"
+                name="diagramCount"
+                register={register}
+                label="Points between X min and X max to sample"
+              />
+            </div>
           </div>
-          <div className="ml-3 text-sm">
-            <label className="font-medium text-gray-700">
-              Show toggles to adjust scale of x and y axes
-            </label>
-          </div>
-        </div>
-        <div className="relative flex items-start">
-          <div className="flex items-center h-5">
-            <input
-              type="checkbox"
-              {...register("showSummary")}
-              className="focus:ring-indigo-500 h-4 w-4 text-indigo-600 border-gray-300 rounded"
-            />
-          </div>
-          <div className="ml-3 text-sm">
-            <label className="font-medium text-gray-700">
-              Show summary statistics
-            </label>
-          </div>
-        </div>
-      </div>
-
-      <div className="space-y-2 pt-8">
-        <h3 className="text-lg leading-6 font-medium text-gray-900 pb-2">
-          Function Display Settings
-        </h3>
-
-        <p className="mt-2 text-sm text-gray-500">
-          When displaying functions of single variables that return numbers or
-          distributions, we need to use defaults for the x-axis. We need to
-          select a minimum and maximum value of x to sample, and a number n of
-          the number of points to sample.
-        </p>
-        <div className="pt-4 grid grid-cols-1 gap-y-4 gap-x-4">
-          <InputItem label="Min X Value">
-            <input
-              type="number"
-              {...register("diagramStart")}
-              className={numberStyle}
-            />
-          </InputItem>
-          <InputItem label="Max X Value">
-            <input
-              type="number"
-              {...register("diagramStop")}
-              className={numberStyle}
-            />
-          </InputItem>
-          <InputItem label="Points between X min and X max to sample">
-            <input
-              type="number"
-              {...register("diagramCount")}
-              className={numberStyle}
-            />
-          </InputItem>
-        </div>
+        </HeadedSection>
       </div>
     </div>
   );
 
-  let inputVariableSettings = (
-    <div className="space-y-6 p-3 max-w-3xl">
-      <h3 className="text-lg leading-6 font-medium text-gray-900">
-        Import Variables from JSON
-      </h3>
-      <p className="mt-2 text-sm text-gray-500">
-        You can import variables from JSON into your Squiggle code. Variables
-        are accessed with dollar signs. For example, "timeNow" would be accessed
-        as "$timeNow".
-      </p>
-      <div className="border border-slate-200 mt-6 mb-2">
-        <JsonEditor
-          value={importString}
-          onChange={getChangeJson}
-          oneLine={false}
-          showGutter={true}
-          height={150}
-        />
-      </div>
-      <div className="p-1 pt-2">
-        {importsAreValid ? (
-          <SuccessAlert heading="Valid Json">
-            <></>
-          </SuccessAlert>
-        ) : (
-          <ErrorAlert heading="Invalid JSON">
-            You must use valid json in this editor.
-          </ErrorAlert>
-        )}
-      </div>
+  const inputVariableSettings = (
+    <div className="p-3 max-w-3xl">
+      <HeadedSection title="Import Variables from JSON">
+        <div className="space-y-6">
+          <Text>
+            You can import variables from JSON into your Squiggle code.
+            Variables are accessed with dollar signs. For example, "timeNow"
+            would be accessed as "$timeNow".
+          </Text>
+          <div className="border border-slate-200 mt-6 mb-2">
+            <JsonEditor
+              value={importString}
+              onChange={getChangeJson}
+              oneLine={false}
+              showGutter={true}
+              height={150}
+            />
+          </div>
+          <div className="p-1 pt-2">
+            {importsAreValid ? (
+              <SuccessAlert heading="Valid JSON" />
+            ) : (
+              <ErrorAlert heading="Invalid JSON">
+                You must use valid JSON in this editor.
+              </ErrorAlert>
+            )}
+          </div>
+        </div>
+      </HeadedSection>
     </div>
   );
 
   return (
     <Tab.Group>
-      <div className=" flex-col flex">
-        <div className="pb-4">
-          <Tab.List className="p-0.5 rounded-md bg-slate-100 hover:bg-slate-200 inline-flex">
-            <StyledTab name="Code" iconName="code" />
-            <StyledTab name="Sampling Settings" iconName="cog" />
-            <StyledTab name="View Settings" iconName="squareBar" />
-            <StyledTab name="Input Variables" iconName="dollar" />
-          </Tab.List>
+      <div className="pb-4">
+        <Tab.List className="flex w-fit p-0.5 rounded-md bg-slate-100 hover:bg-slate-200">
+          <StyledTab name="Code" icon={CodeIcon} />
+          <StyledTab name="Sampling Settings" icon={CogIcon} />
+          <StyledTab name="View Settings" icon={ChartSquareBarIcon} />
+          <StyledTab name="Input Variables" icon={CurrencyDollarIcon} />
+        </Tab.List>
+      </div>
+      <div className="flex" style={{ height }}>
+        <div className="w-1/2">
+          <Tab.Panels>
+            <Tab.Panel>
+              <div className="border border-slate-200">
+                <CodeEditor
+                  value={squiggleString}
+                  onChange={setSquiggleString}
+                  oneLine={false}
+                  showGutter={true}
+                  height={height - 1}
+                />
+              </div>
+            </Tab.Panel>
+            <Tab.Panel>{samplingSettings}</Tab.Panel>
+            <Tab.Panel>{viewSettings}</Tab.Panel>
+            <Tab.Panel>{inputVariableSettings}</Tab.Panel>
+          </Tab.Panels>
         </div>
-        <div className="flex" style={{ height: height + "px" }}>
-          <div className="w-1/2">
-            <Tab.Panels>
-              <Tab.Panel>
-                <div className="border border-slate-200">
-                  <CodeEditor
-                    value={squiggleString}
-                    onChange={setSquiggleString}
-                    oneLine={false}
-                    showGutter={true}
-                    height={height - 1}
-                  />
-                </div>
-              </Tab.Panel>
-              <Tab.Panel>{samplingSettings}</Tab.Panel>
-              <Tab.Panel>{viewSettings}</Tab.Panel>
-              <Tab.Panel>{inputVariableSettings}</Tab.Panel>
-            </Tab.Panels>
-          </div>
 
-          <div className="w-1/2 p-2 pl-4">
-            <div style={{ maxHeight: height + "px" }}>
-              <SquiggleChart
-                squiggleString={squiggleString}
-                environment={env}
-                chartSettings={chartSettings}
-                height={vars.chartHeight}
-                showTypes={vars.showTypes}
-                showControls={vars.showControls}
-                bindings={defaultBindings}
-                jsImports={imports}
-                showSummary={vars.showSummary}
-              />
-            </div>
+        <div className="w-1/2 p-2 pl-4">
+          <div style={{ maxHeight: height }}>
+            <SquiggleChart
+              squiggleString={squiggleString}
+              environment={env}
+              chartSettings={chartSettings}
+              height={vars.chartHeight}
+              showTypes={vars.showTypes}
+              showControls={vars.showControls}
+              bindings={defaultBindings}
+              jsImports={imports}
+              showSummary={vars.showSummary}
+            />
           </div>
         </div>
       </div>
@@ -421,7 +428,7 @@ let SquigglePlayground: FC<PlaygroundProps> = ({
 };
 export default SquigglePlayground;
 export function renderSquigglePlaygroundToDom(props: PlaygroundProps) {
-  let parent = document.createElement("div");
+  const parent = document.createElement("div");
   ReactDOM.render(<SquigglePlayground {...props} />, parent);
   return parent;
 }
diff --git a/packages/components/src/index.ts b/packages/components/src/index.ts
index a35b28bb..3ac4dd0a 100644
--- a/packages/components/src/index.ts
+++ b/packages/components/src/index.ts
@@ -5,9 +5,9 @@ export {
   renderSquiggleEditorToDom,
   renderSquigglePartialToDom,
 } from "./components/SquiggleEditor";
-import SquigglePlayground, {
+export {
+  default as SquigglePlayground,
   renderSquigglePlaygroundToDom,
 } from "./components/SquigglePlayground";
-export { SquigglePlayground, renderSquigglePlaygroundToDom };
 
 export { mergeBindings } from "@quri/squiggle-lang";
diff --git a/packages/components/src/stories/SquiggleChart.stories.js.map b/packages/components/src/stories/SquiggleChart.stories.js.map
deleted file mode 100644
index 1b0db844..00000000
--- a/packages/components/src/stories/SquiggleChart.stories.js.map
+++ /dev/null
@@ -1 +0,0 @@
-{"version":3,"file":"SquiggleChart.stories.js","sourceRoot":"","sources":["SquiggleChart.stories.tsx"],"names":[],"mappings":";;;AAAA,6BAA8B;AAC9B,iDAA+C;AAG/C,qBAAe;IACb,KAAK,EAAE,uBAAuB;IAC9B,SAAS,EAAE,6BAAa;CACzB,CAAA;AAED,IAAM,QAAQ,GAAG,UAAC,EAAgB;QAAf,cAAc,oBAAA;IAAM,OAAA,oBAAC,6BAAa,IAAC,cAAc,EAAE,cAAc,GAAI;AAAjD,CAAiD,CAAA;AAE3E,QAAA,OAAO,GAAG,QAAQ,CAAC,IAAI,CAAC,EAAE,CAAC,CAAA;AACxC,eAAO,CAAC,IAAI,GAAG;IACb,cAAc,EAAE,cAAc;CAC/B,CAAC"}
\ No newline at end of file