Move stringification of display output to Process

This allows me to test the stringification logic, and also means
simulate() tests can rely on the simulated display output being an
array of strings.

src/core/Core.spec.js

@@ -146,9 +146,9 @@ describe('Core', () => {
       })
     `)
     view = core.run()
-    expect(view.displayLines).toEqual([0])
+    expect(view.displayLines).toEqual(['0'])
     view = core.tickFrames(60)
-    expect(view.displayLines).toEqual([3])
+    expect(view.displayLines).toEqual(['3'])
   })
 
   it('outputs the stack trace on a crash', () => {

src/core/Process.js

@@ -1,5 +1,7 @@
-import { isIterator, isGeneratorFunction } from './nativeTypes'
-import { lastOf } from './sequences'
+import { isIterator, isGeneratorFunction, isArray } from './nativeTypes'
+import { doWith } from './functionalUtils'
+import { lastOf, map } from './sequences'
+import { asText } from './formatting'
 
 export function Process(store) {
   let stack = []
@@ -157,7 +159,10 @@ export function Process(store) {
       }
     }
 
-    displayLines = render ? render(store.getState()) : []
+    displayLines = doWith(
+      render ? render(store.getState()) : [],
+      asArray,
+      map(asText))
   }
 
   function view() {
@@ -169,3 +174,7 @@ export function Process(store) {
     }
   }
 }
+
+function asArray(value) {
+  return isArray(value) ? value : [value]
+}

src/core/Process.spec.js

@@ -321,7 +321,7 @@ describe('Process', () => {
       })
       x++
     })
-    expect(view.displayLines).toEqual([1])
+    expect(view.displayLines).toEqual(['1'])
   })
 
   it('passes the state to the render function', () => {
@@ -424,8 +424,8 @@ describe('Process', () => {
       yield startDisplay(() => [redraws++])
       yield wait(1)
     })
-    expect(view.displayLines).toEqual([0])
+    expect(view.displayLines).toEqual(['0'])
     view = p.redraw()
-    expect(view.displayLines).toEqual([1])
+    expect(view.displayLines).toEqual(['1'])
   })
 })

src/core/sequences.js

@@ -1,6 +1,7 @@
 import { isArray, isString } from './nativeTypes'
 import { checkArgs } from './checkArgs'
 import { or } from './predicates'
+import { partialApply } from './higherOrderFunctions'
 
 const lastOf_interface = {
   example: [[1, 2, 3]],
@@ -11,3 +12,11 @@ export function lastOf(list) {
   checkArgs(lastOf, arguments, lastOf_interface)
   return list[list.length - 1]
 }
+
+export function map(fn, seq) {
+  if (arguments.length < 2) {
+    return partialApply(map, arguments)
+  }
+  if (seq.length === 0) return seq
+  return seq.map((item) => fn(item))
+}

src/core/sequences.spec.js

@@ -1,4 +1,4 @@
-import { lastOf } from './sequences'
+import { lastOf, map } from './sequences'
 
 describe('lastOf', function() {
   it('returns undefined for an empty array', () => {
@@ -17,3 +17,23 @@ describe('lastOf', function() {
     expect(lastOf('abc')).toBe('c')
   })
 })
+
+describe('map', function() {
+  function testFn(item) {
+    return item + 1
+  }
+
+  it('returns an empty array unchanged', () => {
+    let a = []
+    expect(map(testFn, a)).toBe(a)
+  })
+
+  it('transforms each array item', () => {
+    expect(map(testFn, [1])).toEqual([2])
+    expect(map(testFn, [1, 2, 3])).toEqual([2, 3, 4])
+  })
+
+  it('curries', () => {
+    expect(map(testFn)([1])).toEqual([2])
+  })
+})

src/ui/components/Terminal.js

@@ -2,7 +2,6 @@ import React from 'react'
 import connectProps from './connectProps'
 import './Terminal.css'
 import Pane from './Pane'
-import { asText } from '../../core/formatting'
 
 export default connectProps(class extends React.Component {
   bottomOfLogs = null
@@ -21,9 +20,13 @@ export default connectProps(class extends React.Component {
     }
   }
 
+  screenLines() {
+    return this.props.appUi.screenLines
+  }
+
   render() {
     let classNames = "Terminal"
-    if (this.props.appUi.screenLines.length) classNames += ' showScreen'
+    if (this.screenLines().length) classNames += ' showScreen'
     return (
       <Pane style={{height: '608px', width: '100%'}}>
         <div className={classNames}>
@@ -36,8 +39,7 @@ export default connectProps(class extends React.Component {
           </div>
           <div className="screen">
             {
-              this.props.appUi.screenLines
-                .map(asText)
+              this.screenLines()
                 .map((line, i) =>
                   <div className="line" key={i}>{line}</div>)
             }