bump to v4.6.1

This reverts commit 381930e547.

.github/workflows/build.yml

@@ -1,6 +1,8 @@
 name: Build
 run-name: Build the project
-on: [push]
+on:
+  workflow_dispatch:
+  push:
 jobs:
   build:
     runs-on: ubuntu-latest

client/src/components/hints.tsx

@@ -5,15 +5,33 @@ import { DeletedChatContext, ProofContext } from "./infoview/context";
 import { lastStepHasErrors } from "./infoview/goals";
 import { Button } from "./button";
 
+/** Plug-in the variable names in a hint. We do this client-side to prepare
+ * for i18n in the future. i.e. one should be able translate the `rawText`
+ * and have the variables substituted just before displaying.
+ */
+function getHintText(hint: GameHint): string {
+  if (hint.rawText) {
+    // Replace the variable names used in the hint with the ones used by the player
+    // variable names are marked like `«{g}»` inside the text.
+    return hint.rawText.replaceAll(/«\{(.*?)\}»/g, ((_, v) =>
+      // `hint.varNames` contains tuples `[oldName, newName]`
+      (hint.varNames.find(x => x[0] == v))[1]))
+  } else {
+    // hints created in the frontend do not have a `rawText`
+    // TODO: `hint.text` could be removed in theory.
+    return hint.text
+  }
+}
+
 export function Hint({hint, step, selected, toggleSelection, lastLevel} : {hint: GameHint, step: number, selected: number, toggleSelection: any, lastLevel?: boolean}) {
   return <div className={`message information step-${step}` + (step == selected ? ' selected' : '') + (lastLevel ? ' recent' : '')} onClick={toggleSelection}>
-    <Markdown>{hint.text}</Markdown>
+    <Markdown>{getHintText(hint)}</Markdown>
   </div>
 }
 
 export function HiddenHint({hint, step, selected, toggleSelection, lastLevel} : {hint: GameHint, step: number, selected: number, toggleSelection: any, lastLevel?: boolean}) {
   return <div className={`message warning step-${step}` + (step == selected ? ' selected' : '') + (lastLevel ? ' recent' : '')} onClick={toggleSelection}>
-    <Markdown>{hint.text}</Markdown>
+    <Markdown>{getHintText(hint)}</Markdown>
   </div>
 }
 
@@ -31,7 +49,7 @@ export function Hints({hints, showHidden, step, selected, toggleSelection, lastL
 
 export function DeletedHint({hint} : {hint: GameHint}) {
   return <div className="message information deleted-hint">
-    <Markdown>{hint.text}</Markdown>
+    <Markdown>{getHintText(hint)}</Markdown>
   </div>
 }
 
@@ -73,12 +91,14 @@ export function MoreHelpButton({selected=null} : {selected?: number}) {
   const {proof, setProof} = React.useContext(ProofContext)
   const {deletedChat, setDeletedChat, showHelp, setShowHelp} = React.useContext(DeletedChatContext)
 
-  let k = (selected === null) ? (proof.steps.length - (lastStepHasErrors(proof) ? 2 : 1)) : selected
+  let k = proof?.steps.length ?
+    ((selected === null) ? (proof?.steps.length - (lastStepHasErrors(proof) ? 2 : 1)) : selected)
+    : 0
 
   const activateHiddenHints = (ev) => {
     // If the last step (`k`) has errors, we want the hidden hints from the
     // second-to-last step to be affected
-    if (!(proof.steps.length)) {return}
+    if (!(proof?.steps.length)) {return}
 
     // state must not be mutated, therefore we need to clone the set
     let tmp = new Set(showHelp)
@@ -91,7 +111,7 @@ export function MoreHelpButton({selected=null} : {selected?: number}) {
     console.debug(`help: ${Array.from(tmp.values())}`)
   }
 
-  if (hasHiddenHints(proof.steps[k]) && !showHelp.has(k)) {
+  if (hasHiddenHints(proof?.steps[k]) && !showHelp.has(k)) {
     return <Button to="" onClick={activateHiddenHints}>
       Show more help!
     </Button>

client/src/components/infoview/context.ts

@@ -4,6 +4,7 @@
 import * as React from 'react';
 import * as monaco from 'monaco-editor/esm/vs/editor/editor.api.js'
 import { InteractiveDiagnostic } from '@leanprover/infoview-api';
+import { Diagnostic } from 'vscode-languageserver-types'
 import { GameHint, InteractiveGoal, InteractiveTermGoal,InteractiveGoalsWithHints, ProofState } from './rpc_api';
 import { PreferencesState } from '../../state/preferences';
 
@@ -33,9 +34,19 @@ export const ProofContext = React.createContext<{
    */
   proof: ProofState,
   setProof: React.Dispatch<React.SetStateAction<ProofState>>
+  /** TODO: Workaround to capture a crash of the gameserver. */
+  interimDiags: Diagnostic[],
+  setInterimDiags: React.Dispatch<React.SetStateAction<Array<Diagnostic>>>
+  /** TODO: Workaround to capture a crash of the gameserver. */
+  crashed: Boolean,
+  setCrashed: React.Dispatch<React.SetStateAction<Boolean>>
 }>({
-  proof: {steps: [], diagnostics: [], completed: false},
+  proof: {steps: [], diagnostics: [], completed: false, completedWithWarnings: false},
-  setProof: () => {}
+  setProof: () => {},
+  interimDiags: [],
+  setInterimDiags: () => {},
+  crashed: false,
+  setCrashed: () => {}
 })
 
 

client/src/components/infoview/goals.tsx

@@ -268,7 +268,7 @@ interface GoalsProps {
 
 export function Goals({ goals, filter }: GoalsProps) {
     if (goals.goals.length === 0) {
-        return <>No goals</>
+        return <></>
     } else {
         return <>
           {goals.goals.map((g, i) => <Goal typewriter={false} key={i} goal={g.goal} filter={filter} />)}
@@ -345,96 +345,29 @@ export const FilteredGoals = React.memo(({ headerChildren, goals }: FilteredGoal
 })
 
 export function loadGoals(
-    rpcSess: RpcSessionAtPos,
+  rpcSess: RpcSessionAtPos,
-    uri: string,
+  uri: string,
-    setProof: React.Dispatch<React.SetStateAction<ProofState>>) {
+  setProof: React.Dispatch<React.SetStateAction<ProofState>>,
-  console.info('sending rpc request to load the proof state')
+  setCrashed: React.Dispatch<React.SetStateAction<Boolean>>) {
+console.info('sending rpc request to load the proof state')
 
-  rpcSess.call('Game.getProofState', DocumentPosition.toTdpp({line: 0, character: 0, uri: uri})).then(
+rpcSess.call('Game.getProofState', DocumentPosition.toTdpp({line: 0, character: 0, uri: uri})).then(
-    (proof : ProofState) => {
+  (proof : ProofState) => {
+    if (typeof proof !== 'undefined') {
       console.info(`received a proof state!`)
       console.log(proof)
       setProof(proof)
-
+      setCrashed(false)
-
+    } else {
-
+      console.warn('received undefined proof state!')
-
+      setCrashed(true)
-      // let tmpProof : ProofStep[] = []
+      // setProof(undefined)
-
-      // let goalCount = 0
-
-      // steps.map((goals, i) => {
-      //   // The first step has an empty command and therefore also no error messages
-      //   // Usually there is a newline at the end of the editors content, so we need to
-      //   // display diagnostics from potentally two lines in the last step.
-      //   let messages = i ? (i == steps.length - 1 ? diagnostics.slice(i-1).flat() : diagnostics[i-1]) : []
-
-      //   // Filter out the 'unsolved goals' message
-      //   messages = messages.filter((msg) => {
-      //     return !("append" in msg.message &&
-      //       "text" in msg.message.append[0] &&
-      //       msg.message.append[0].text === "unsolved goals")
-      //   })
-
-      //   if (typeof goals == 'undefined') {
-      //     tmpProof.push({
-      //       command: i ? model.getLineContent(i) : '',
-      //       goals: [],
-      //       hints: [],
-      //       errors: messages
-      //     } as ProofStep)
-      //     console.debug('goals is undefined')
-      //     return
-      //   }
-
-      //   // If the number of goals reduce, show a message
-      //   if (goals.length && goalCount > goals.length) {
-      //     messages.unshift({
-      //       range: {
-      //         start: {
-      //           line: i-1,
-      //           character: 0,
-      //         },
-      //         end: {
-      //           line: i-1,
-      //           character: 0,
-      //         }},
-      //       severity: DiagnosticSeverity.Information,
-      //       message: {
-      //       text: 'intermediate goal solved 🎉'
-      //       }
-      //     })
-      //   }
-      //   goalCount = goals.length
-
-      //   // with no goals there will be no hints.
-      //   let hints : GameHint[] = goals.length ? goals[0].hints : []
-
-      //   console.debug(`Command (${i}): `, i ? model.getLineContent(i) : '')
-      //   console.debug(`Goals: (${i}): `, goalsToString(goals)) //
-      //   console.debug(`Hints: (${i}): `, hints)
-      //   console.debug(`Errors: (${i}): `, messages)
-
-      //   tmpProof.push({
-      //     // the command of the line above. Note that `getLineContent` starts counting
-      //     // at `1` instead of `zero`. The first ProofStep will have an empty command.
-      //     command: i ? model.getLineContent(i) : '',
-      //     // TODO: store correct data
-      //     goals: goals.map(g => g.goal),
-      //     // only need the hints of the active goals in chat
-      //     hints: hints,
-      //     // errors and messages from the server
-      //     errors: messages
-      //   } as ProofStep)
-
-      // })
-      // // Save the proof to the context
-      // setProof(tmpProof)
-
-
-
     }
-  )
+  }
+).catch((error) => {
+  setCrashed(true)
+  console.warn(error)
+})
 }
 
 

client/src/components/infoview/info.tsx

@@ -293,7 +293,9 @@ function InfoAux(props: InfoProps) {
     type InfoRequestResult = Omit<InfoDisplayProps, 'triggerUpdate'>
     const [state, triggerUpdateCore] = useAsyncWithTrigger(() => new Promise<InfoRequestResult>((resolve, reject) => {
 
-        const proofReq = rpcSess.call('Game.getProofState', DocumentPosition.toTdpp(pos))
+        const proofReq = rpcSess.call('Game.getProofState', DocumentPosition.toTdpp(pos)).catch((error) => {
+            console.warn(error)
+          })
         const goalsReq = rpcSess.call('Game.getInteractiveGoals', DocumentPosition.toTdpp(pos))
         const termGoalReq = getInteractiveTermGoal(rpcSess, DocumentPosition.toTdpp(pos))
         const widgetsReq = Widget_getWidgets(rpcSess, pos).catch(discardMethodNotFound)

client/src/components/infoview/main.tsx

@@ -36,6 +36,7 @@ import { GameHint, InteractiveGoalsWithHints, ProofState } from './rpc_api';
 import { store } from '../../state/store';
 import { Hints, MoreHelpButton, filterHints } from '../hints';
 import { DocumentPosition } from '../../../../node_modules/lean4-infoview/src/infoview/util';
+import { DiagnosticSeverity } from 'vscode-languageclient';
 
 /** Wrapper for the two editors. It is important that the `div` with `codeViewRef` is
  * always present, or the monaco editor cannot start.
@@ -67,7 +68,7 @@ function DualEditorMain({ worldId, levelId, level, worldSize }: { worldId: strin
   const dispatch = useAppDispatch()
 
   React.useEffect(() => {
-    if (proof.completed) {
+    if (proof?.completed) {
       dispatch(levelCompleted({ game: gameId, world: worldId, level: levelId }))
 
       // On completion, add the names of all new items to the local storage
@@ -232,12 +233,16 @@ export function Main(props: { world: string, level: number, data: LevelInfo}) {
     ret = <div><p>{serverStoppedResult.message}</p><p className="error">{serverStoppedResult.reason}</p></div>
   } else {
     ret = <div className="infoview vscode-light">
-      {proof.completed && <div className="level-completed">Level completed! 🎉</div>}
+      {proof?.completedWithWarnings &&
+        <div className="level-completed">
+          {proof?.completed ? "Level completed! 🎉" : "Level completed with warnings 🎭"}
+        </div>
+      }
       <Infos />
-      <Hints hints={proof.steps[curPos?.line]?.goals[0]?.hints}
+      <Hints hints={proof?.steps[curPos?.line]?.goals[0]?.hints}
         showHidden={showHelp.has(curPos?.line)} step={curPos?.line}
         selected={selectedStep} toggleSelection={toggleSelection(curPos?.line)}
-        lastLevel={curPos?.line == proof.steps.length - 1}/>
+        lastLevel={curPos?.line == proof?.steps.length - 1}/>
       <MoreHelpButton selected={curPos?.line}/>
     </div>
   }
@@ -262,11 +267,11 @@ function Command({ proof, i, deleteProof }: { proof: ProofState, i: number, dele
     // If the last step has errors, we display the command in a different style
     // indicating that it will be removed on the next try.
     return <div className="failed-command">
-      <i>Failed command</i>: {proof.steps[i].command}
+      <i>Failed command</i>: {proof?.steps[i].command}
     </div>
   } else {
     return <div className="command">
-      <div className="command-text">{proof.steps[i].command}</div>
+      <div className="command-text">{proof?.steps[i].command}</div>
       <Button to="" className="undo-button btn btn-inverted" title="Retry proof from here" onClick={deleteProof}>
         <FontAwesomeIcon icon={faDeleteLeft} />&nbsp;Retry
       </Button>
@@ -394,7 +399,7 @@ export function TypewriterInterface({props}) {
   const [loadingProgress, setLoadingProgress] = React.useState<number>(0)
   const { setDeletedChat, showHelp, setShowHelp } = React.useContext(DeletedChatContext)
   const {mobile} = React.useContext(PreferencesContext)
-  const { proof, setProof } = React.useContext(ProofContext)
+  const { proof, setProof, crashed, setCrashed, interimDiags } = React.useContext(ProofContext)
   const { setTypewriterInput } = React.useContext(InputModeContext)
   const { selectedStep, setSelectedStep } = React.useContext(SelectionContext)
 
@@ -410,7 +415,7 @@ export function TypewriterInterface({props}) {
   function deleteProof(line: number) {
     return (ev) => {
       let deletedChat: Array<GameHint> = []
-      proof.steps.slice(line).map((step, i) => {
+      proof?.steps.slice(line).map((step, i) => {
         let filteredHints = filterHints(step.goals[0]?.hints, proof?.steps[i-1]?.goals[0]?.hints)
 
         // Only add these hidden hints to the deletion stack which were visible
@@ -427,9 +432,9 @@ export function TypewriterInterface({props}) {
         forceMoveMarkers: false
       }])
       setSelectedStep(undefined)
-      setTypewriterInput(proof.steps[line].command)
+      setTypewriterInput(proof?.steps[line].command)
       // Reload proof on deleting
-      loadGoals(rpcSess, uri, setProof)
+      loadGoals(rpcSess, uri, setProof, setCrashed)
       ev.stopPropagation()
     }
   }
@@ -449,7 +454,7 @@ export function TypewriterInterface({props}) {
 
    // Scroll to the end of the proof if it is updated.
    React.useEffect(() => {
-    if (proof.steps.length > 1) {
+    if (proof?.steps.length > 1) {
       proofPanelRef.current?.lastElementChild?.scrollIntoView() //scrollTo(0,0)
     } else {
       proofPanelRef.current?.scrollTo(0,0)
@@ -471,7 +476,7 @@ export function TypewriterInterface({props}) {
   }, [selectedStep])
 
   // TODO: superfluous, can be replaced with `withErr` from above
-  let lastStepErrors = proof.steps.length ? hasInteractiveErrors(getInteractiveDiagsAt(proof, proof.steps.length)) : false
+  let lastStepErrors = proof?.steps.length ? hasInteractiveErrors(getInteractiveDiagsAt(proof, proof?.steps.length)) : false
 
 
   useServerNotificationEffect("$/game/loading", (params : any) => {
@@ -491,12 +496,33 @@ export function TypewriterInterface({props}) {
       </div>
       <div className='proof' ref={proofPanelRef}>
         <ExerciseStatement data={props.data} />
-        {proof.steps.length ?
+        {crashed ? <div>
+          <p className="crashed_message">Crashed! Go to editor mode and fix your proof!
+          Last server response:</p>
+          {interimDiags.map(diag => {
+            const severityClass = diag.severity ? {
+              [DiagnosticSeverity.Error]: 'error',
+              [DiagnosticSeverity.Warning]: 'warning',
+              [DiagnosticSeverity.Information]: 'information',
+              [DiagnosticSeverity.Hint]: 'hint',
+            }[diag.severity] : '';
+
+            return <div>
+              <div className={`${severityClass} ml1 message`}>
+                <p className="mv2">Line {diag.range.start.line}, Character {diag.range.start.character}</p>
+                <pre className="font-code pre-wrap">
+                  {diag.message}
+                </pre>
+                </div>
+            </div>
+          })}
+
+        </div> : proof?.steps.length ?
           <>
-            {proof.steps.map((step, i) => {
+            {proof?.steps.map((step, i) => {
               let filteredHints = filterHints(step.goals[0]?.hints, proof?.steps[i-1]?.goals[0]?.hints)
 
-              // if (i == proof.steps.length - 1 && hasInteractiveErrors(step.diags)) {
+              // if (i == proof?.steps.length - 1 && hasInteractiveErrors(step.diags)) {
               //   // if the last command contains an error, we only display the errors but not the
               //   // entered command as it is still present in the command line.
               //   // TODO: Should not use index as key.
@@ -517,18 +543,18 @@ export function TypewriterInterface({props}) {
                       hints={filteredHints} showHidden={showHelp.has(i)} step={i}
                       selected={selectedStep} toggleSelection={toggleSelectStep(i)}/>
                   }
-                  {/* <GoalsTabs proofStep={step} last={i == proof.steps.length - (lastStepErrors ? 2 : 1)} onClick={toggleSelectStep(i)} onGoalChange={i == proof.steps.length - 1 - withErr ? (n) => setDisableInput(n > 0) : (n) => {}}/> */}
+                  {/* <GoalsTabs proofStep={step} last={i == proof?.steps.length - (lastStepErrors ? 2 : 1)} onClick={toggleSelectStep(i)} onGoalChange={i == proof?.steps.length - 1 - withErr ? (n) => setDisableInput(n > 0) : (n) => {}}/> */}
                   {!(isLastStepWithErrors(proof, i)) &&
-                    <GoalsTabs proofStep={step} last={i == proof.steps.length - (lastStepHasErrors(proof) ? 2 : 1)} onClick={toggleSelectStep(i)} onGoalChange={i == proof.steps.length - (lastStepHasErrors(proof) ? 2 : 1) ? (n) => setDisableInput(n > 0) : (n) => {}}/>
+                    <GoalsTabs proofStep={step} last={i == proof?.steps.length - (lastStepHasErrors(proof) ? 2 : 1)} onClick={toggleSelectStep(i)} onGoalChange={i == proof?.steps.length - (lastStepHasErrors(proof) ? 2 : 1) ? (n) => setDisableInput(n > 0) : (n) => {}}/>
                   }
-                  {mobile && i == proof.steps.length - 1 &&
+                  {mobile && i == proof?.steps.length - 1 &&
                     <MoreHelpButton />
                   }
 
                   {/* Show a message that there are no goals left */}
                   {/* {!step.goals.length && (
                     <div className="message information">
-                      {proof.completed ?
+                      {proof?.completed ?
                         <p>Level completed! 🎉</p> :
                         <p>
                           <b>no goals left</b><br />
@@ -541,12 +567,12 @@ export function TypewriterInterface({props}) {
               }
             //}
             )}
-            {proof.diagnostics.length > 0 &&
+            {proof?.diagnostics.length > 0 &&
               <div key={`proof-step-remaining`} className="step step-remaining">
-                <Errors errors={proof.diagnostics} typewriterMode={true} />
+                <Errors errors={proof?.diagnostics} typewriterMode={true} />
               </div>
             }
-            {mobile && proof.completed &&
+            {mobile && proof?.completed &&
               <div className="button-row mobile">
                 {props.level >= props.worldSize ?
                   <Button to={`/${gameId}`}>
@@ -559,11 +585,14 @@ export function TypewriterInterface({props}) {
                 }
               </div>
             }
-          </> : <CircularProgress variant="determinate" value={loadingProgress} />
+          </> : <CircularProgress variant="determinate" value={100*(1 - 1.024 ** (- loadingProgress))} />
+        // note: since we don't know the total number of files,
+        // we use a function which strictly monotonely increases towards `100` as `x → ∞`
+        // The base is chosen at random s.t. we get roughly 91% for `x = 100`.
         }
       </div>
     </div>
-    <Typewriter disabled={disableInput || !proof.steps.length}/>
+    <Typewriter disabled={disableInput || !proof?.steps.length}/>
     </RpcContext.Provider>
   </div>
 }

client/src/components/infoview/rpc_api.ts

@@ -49,6 +49,8 @@ export interface InteractiveTermGoal extends InteractiveGoalCore {
 export interface GameHint {
   text: string;
   hidden: boolean;
+  rawText: string;
+  varNames: string[][]; // in Lean: `Array (Name × Name)`
 }
 
 export interface InteractiveGoalWithHints {

client/src/components/infoview/typewriter.tsx

@@ -87,7 +87,7 @@ export function Typewriter({disabled}: {disabled?: boolean}) {
   const inputRef = useRef()
 
   // The context storing all information about the current proof
-  const {proof, setProof} = React.useContext(ProofContext)
+  const {proof, setProof, interimDiags, setInterimDiags, setCrashed} = React.useContext(ProofContext)
 
   // state to store the last batch of deleted messages
   const {setDeletedChat} = React.useContext(DeletedChatContext)
@@ -210,7 +210,7 @@ export function Typewriter({disabled}: {disabled?: boolean}) {
       }])
       setTypewriterInput('')
       // Load proof after executing edits
-      loadGoals(rpcSess, uri, setProof)
+      loadGoals(rpcSess, uri, setProof, setCrashed)
     }
 
     editor.setPosition(pos)
@@ -224,13 +224,13 @@ export function Typewriter({disabled}: {disabled?: boolean}) {
 
   /* Load proof on start/switching to typewriter */
   useEffect(() => {
-    loadGoals(rpcSess, uri, setProof)
+    loadGoals(rpcSess, uri, setProof, setCrashed)
   }, [])
 
   /** If the last step has an error, add the command to the typewriter. */
   useEffect(() => {
     if (lastStepHasErrors(proof)) {
-      setTypewriterInput(proof.steps[proof.steps.length - 1].command)
+      setTypewriterInput(proof?.steps[proof?.steps.length - 1].command)
     }
   }, [proof])
 
@@ -238,6 +238,11 @@ export function Typewriter({disabled}: {disabled?: boolean}) {
   useServerNotificationEffect('textDocument/publishDiagnostics', (params: PublishDiagnosticsParams) => {
     if (params.uri == uri) {
       setProcessing(false)
+
+      console.log('Received lean diagnostics')
+      console.log(params.diagnostics)
+      setInterimDiags(params.diagnostics)
+
       //loadGoals(rpcSess, uri, setProof)
 
       // TODO: loadAllGoals()
@@ -254,13 +259,13 @@ export function Typewriter({disabled}: {disabled?: boolean}) {
     // loadAllGoals()
   }, [uri]);
 
-  // React when answer from the server comes back
+  // // React when answer from the server comes back
-  useServerNotificationEffect('$/game/publishDiagnostics', (params: GameDiagnosticsParams) => {
+  // useServerNotificationEffect('$/game/publishDiagnostics', (params: GameDiagnosticsParams) => {
-    console.log('Received game diagnostics')
+  //   console.log('Received game diagnostics')
-    console.log(`diag. uri : ${params.uri}`)
+  //   console.log(`diag. uri : ${params.uri}`)
-    console.log(params.diagnostics)
+  //   console.log(params.diagnostics)
 
-  }, [uri]);
+  // }, [uri]);
 
 
   useEffect(() => {
@@ -344,7 +349,7 @@ export function Typewriter({disabled}: {disabled?: boolean}) {
   }
 
   // do not display if the proof is completed (with potential warnings still present)
-  return <div className={`typewriter${proof.completedWithWarnings ? ' hidden' : ''}${disabled ? ' disabled' : ''}`}>
+  return <div className={`typewriter${proof?.completedWithWarnings ? ' hidden' : ''}${disabled ? ' disabled' : ''}`}>
       <form onSubmit={handleSubmit}>
         <div className="typewriter-input-wrapper">
           <div ref={inputRef} className="typewriter-input" />
@@ -376,10 +381,10 @@ export function hasInteractiveErrors (diags: InteractiveDiagnostic[]) {
 export function getInteractiveDiagsAt (proof: ProofState, k : number) {
   if (k == 0) {
     return []
-  } else if (k >= proof.steps.length-1) {
+  } else if (k >= proof?.steps.length-1) {
     // TODO: Do we need that?
-    return proof.diagnostics.filter(msg => msg.range.start.line >= proof.steps.length-1)
+    return proof?.diagnostics.filter(msg => msg.range.start.line >= proof?.steps.length-1)
   } else {
-    return proof.diagnostics.filter(msg => msg.range.start.line == k-1)
+    return proof?.diagnostics.filter(msg => msg.range.start.line == k-1)
   }
 }

client/src/components/level.tsx

@@ -16,6 +16,7 @@ import { InfoviewApi } from '@leanprover/infoview'
 import { EditorContext } from '../../../node_modules/lean4-infoview/src/infoview/contexts'
 import { EditorConnection, EditorEvents } from '../../../node_modules/lean4-infoview/src/infoview/editorConnection'
 import { EventEmitter } from '../../../node_modules/lean4-infoview/src/infoview/event'
+import { Diagnostic } from 'vscode-languageserver-types'
 
 import { GameIdContext } from '../app'
 import { useAppDispatch, useAppSelector } from '../hooks'
@@ -84,7 +85,7 @@ function ChatPanel({lastLevel, visible = true}) {
   const {selectedStep, setSelectedStep} = useContext(SelectionContext)
   const completed = useAppSelector(selectCompleted(gameId, worldId, levelId))
 
-  let k = proof.steps.length - (lastStepHasErrors(proof) ? 2 : 1)
+  let k = proof?.steps.length ? proof?.steps.length - (lastStepHasErrors(proof) ? 2 : 1) : 0
 
   function toggleSelection(line: number) {
     return (ev) => {
@@ -127,29 +128,29 @@ function ChatPanel({lastLevel, visible = true}) {
       {introText?.filter(t => t.trim()).map(((t, i) =>
         // Show the level's intro text as hints, too
         <Hint key={`intro-p-${i}`}
-          hint={{text: t, hidden: false}} step={0} selected={selectedStep} toggleSelection={toggleSelection(0)} />
+          hint={{text: t, hidden: false, rawText: t, varNames: []}} step={0} selected={selectedStep} toggleSelection={toggleSelection(0)} />
       ))}
-      {proof.steps.map((step, i) => {
+      {proof?.steps.map((step, i) => {
         let filteredHints = filterHints(step.goals[0]?.hints, proof?.steps[i-1]?.goals[0]?.hints)
         if (step.goals.length > 0 && !isLastStepWithErrors(proof, i)) {
           return <Hints key={`hints-${i}`}
           hints={filteredHints} showHidden={showHelp.has(i)} step={i}
-          selected={selectedStep} toggleSelection={toggleSelection(i)} lastLevel={i == proof.steps.length - 1}/>
+          selected={selectedStep} toggleSelection={toggleSelection(i)} lastLevel={i == proof?.steps.length - 1}/>
         }
       })}
 
       {/* {modifiedHints.map((step, i) => {
         // It the last step has errors, it will have the same hints
         // as the second-to-last step. Therefore we should not display them.
-        if (!(i == proof.steps.length - 1 && withErr)) {
+        if (!(i == proof?.steps.length - 1 && withErr)) {
           // TODO: Should not use index as key.
           return <Hints key={`hints-${i}`}
             hints={step} showHidden={showHelp.has(i)} step={i}
-            selected={selectedStep} toggleSelection={toggleSelection(i)} lastLevel={i == proof.steps.length - 1}/>
+            selected={selectedStep} toggleSelection={toggleSelection(i)} lastLevel={i == proof?.steps.length - 1}/>
         }
       })} */}
       <DeletedHints hints={deletedChat}/>
-      {proof.completed &&
+      {proof?.completed &&
         <>
           <div className={`message information recent step-${k}${selectedStep == k ? ' selected' : ''}`} onClick={toggleSelection(k)}>
             Level completed! 🎉
@@ -163,7 +164,7 @@ function ChatPanel({lastLevel, visible = true}) {
       }
     </div>
     <div className="button-row">
-      {proof.completed && (lastLevel ?
+      {proof?.completed && (lastLevel ?
         <Button to={`/${gameId}`}>
           <FontAwesomeIcon icon={faHome} />&nbsp;Leave World
         </Button> :
@@ -208,6 +209,10 @@ function PlayableLevel({impressum, setImpressum}) {
 
   // The state variables for the `ProofContext`
   const [proof, setProof] = useState<ProofState>({steps: [], diagnostics: [], completed: false, completedWithWarnings: false})
+  const [interimDiags, setInterimDiags] = useState<Array<Diagnostic>>([])
+  const [isCrashed, setIsCrashed] = useState<Boolean>(false)
+
+
   // When deleting the proof, we want to keep to old messages around until
   // a new proof has been entered. e.g. to consult messages coming from dead ends
   const [deletedChat, setDeletedChat] = useState<Array<GameHint>>([])
@@ -334,15 +339,15 @@ function PlayableLevel({impressum, setImpressum}) {
 
   useEffect(() => {
     // Forget whether hidden hints are displayed for steps that don't exist yet
-    if (proof.steps.length) {
+    if (proof?.steps.length) {
       console.debug(Array.from(showHelp))
-      setShowHelp(new Set(Array.from(showHelp).filter(i => (i < proof.steps.length))))
+      setShowHelp(new Set(Array.from(showHelp).filter(i => (i < proof?.steps.length))))
     }
   }, [proof])
 
   // save showed help in store
   useEffect(() => {
-    if (proof.steps.length) {
+    if (proof?.steps.length) {
       console.debug(`showHelp:\n ${showHelp}`)
       dispatch(helpEdited({game: gameId, world: worldId, level: levelId, help: Array.from(showHelp)}))
     }
@@ -380,7 +385,7 @@ function PlayableLevel({impressum, setImpressum}) {
     <DeletedChatContext.Provider value={{deletedChat, setDeletedChat, showHelp, setShowHelp}}>
       <SelectionContext.Provider value={{selectedStep, setSelectedStep}}>
         <InputModeContext.Provider value={{typewriterMode, setTypewriterMode, typewriterInput, setTypewriterInput, lockInputMode, setLockInputMode}}>
-          <ProofContext.Provider value={{proof, setProof}}>
+          <ProofContext.Provider value={{proof, setProof, interimDiags, setInterimDiags, crashed: isCrashed, setCrashed: setIsCrashed}}>
             <EditorContext.Provider value={editorConnection}>
               <MonacoEditorContext.Provider value={editor}>
                 <LevelAppBar
@@ -427,7 +432,7 @@ function IntroductionPanel({gameInfo}) {
     <div className="chat">
       {text?.filter(t => t.trim()).map(((t, i) =>
         <Hint key={`intro-p-${i}`}
-          hint={{text: t, hidden: false}} step={0} selected={null} toggleSelection={undefined} />
+          hint={{text: t, hidden: false, rawText: t, varNames: []}} step={0} selected={null} toggleSelection={undefined} />
       ))}
     </div>
     <div className={`button-row${mobile ? ' mobile' : ''}`}>

client/src/css/infoview.css

@@ -41,6 +41,13 @@
 .level-completed {
   font-size: 1.8rem;
   font-weight: 500;
+  padding-left: .5em;
+  padding-right: .5em;
+  padding-top: .2em;
+  padding-bottom: .2em;
+  border-radius: .5em;
+  background-color: #eee;
+
 }
 
 .typewriter {
@@ -211,3 +218,10 @@
 .undo-button {
   color: #888;
 }
+
+.crashed_message {
+  color: #D8000C;
+  font-weight: bold;
+  padding-left: .5em;
+  padding-right: .5em;
+}

client/src/css/level.css

@@ -370,6 +370,6 @@ td code  {
 }
 
 /* DEBUG */
-.proof .step {
+/* .proof .step {
   border: 2px solid rgb(0, 123, 255);
-}
+} */

doc/create_game.md

@@ -189,8 +189,7 @@ The statement is the exercise of the level. The basics work the same as they wou
 
 #### Name
 
-You can give your exercise a name: `Statement my_first_exercise (n : Nat) ...`. If you do so, it will be added to the inventory and be available in future levels.
+You can give your exercise a name: `Statement my_first_exercise (n : Nat) …`. If you do so, it will be added to the inventory and be available in future levels.
-
 You can but a `Statement` inside namespaces like you would with `theorem`.
 
 #### Doc String / Exercise statement
@@ -203,6 +202,28 @@ Statement ...
   sorry
 ```
 
+#### Local `let` definitions
+
+If you want to make a local definition/notation which only holds for this exercise (e.g.
+a function `f : ℤ → ℤ := fun x ↦ 2 * x`) the recommended way is to use a `let`-statement:
+
+```lean
+Statement (a : ℤ) (h : 0 < a) :
+    let f : ℤ → ℤ := fun x ↦ 2 * x
+    0 < f a := by
+  sorry
+```
+
+The game automatically `intros` such `let`-statements, such that you and the player will see
+the following initial proof state:
+
+```
+a: ℤ
+h: 0 < a
+f: ℤ → ℤ := fun x => 2 * x
+⊢ 0 < f a
+```
+
 #### Attributes
 
 You can add attributes as you would for a `theorem`. Most notably, you can make your named exercise a `simp` lemma:

doc/hints.md

@@ -86,4 +86,36 @@ create new assumptions.
 
 You can add use markdown to format your hints, for example you can use KaTex: `$\\iff$`
 
+**Escaping**: Generally, if you add text inside quotes `" "` (e.g. in `Hint`) you need to escape
+backslashes, but if you provide text inside a doc comment
+`/-- -/` (e.g. in the `Statement` description) you do not!
+
 TODO: Write a doc about latex/markdown options available.
+
+### Commutative diagrams
+
+Here is an example of how to write a commutative diagram in KaTeX:
+
+$$
+\begin{CD}
+      A  @>{f}>> B @<{g}<< C    \\
+  @V{h}VV    @V{i}VV   @V{j}VV \\
+      D  @<{k}<< E @>{l}>> F    \\
+  @A{m}AA    @A{n}AA   @V{p}VV \\
+      G  @<{q}<< H @>{r}>> I
+\end{CD}
+$$
+
+```
+$$
+\\begin{CD}
+      A  @>{f}>> B @<{g}<< C    \\\\
+  @V{h}VV    @V{i}VV   @V{j}VV \\\\
+      D  @<{k}<< E @>{l}>> F    \\\\
+  @A{m}AA    @A{n}AA   @V{p}VV \\\\
+      G  @<{q}<< H @>{r}>> I
+\\end{CD}
+$$
+```
+
+See https://www.jmilne.org/not/Mamscd.pdf

doc/troubleshoot.md

@@ -2,6 +2,15 @@
 
 Here are some issues experienced by users.
 
+- You can reset the lake projects involved (i.e. the `server/` folder here as well as your [game's folder](https://github.com/hhu-adam/GameSkeleton)) with the following commands:
+  ```
+  cd [THE PROJECT]
+  rm -rf .lake/
+  lake update -R
+  lake build
+  ```
+  If you experience problems related to Lean or lake, you should first try to reset it this way.
+
 # VSCode Dev-Container
 * If you don't get the pop-up, you might have disabled them, and you can reenable it by
   running the `remote-containers.showReopenInContainerNotificationReset` command in vscode.

package-lock.json

@@ -8753,9 +8753,9 @@
       }
     },
     "node_modules/ip": {
-      "version": "1.1.8",
+      "version": "1.1.9",
-      "resolved": "https://registry.npmjs.org/ip/-/ip-1.1.8.tgz",
+      "resolved": "https://registry.npmjs.org/ip/-/ip-1.1.9.tgz",
-      "integrity": "sha512-PuExPYUiu6qMBQb4l06ecm6T6ujzhmh+MeJcW9wa89PoAz5pvd4zPgN5WJV104mb6S2T1AwNIAaB70JNrLQWhg=="
+      "integrity": "sha512-cyRxvOEpNHNtchU3Ln9KC/auJgup87llfQpQ+t5ghoC/UhL16SWzbueiCsdTnWmqAWl7LadfuwhlqmtOaqMHdQ=="
     },
     "node_modules/ip-anonymize": {
       "version": "0.1.0",
@@ -14341,6 +14341,14 @@
         "node": ">=6"
       }
     },
+    "node_modules/stacktrace-parser/node_modules/type-fest": {
+      "version": "0.7.1",
+      "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-0.7.1.tgz",
+      "integrity": "sha512-Ne2YiiGN8bmrmJJEuTWTLJR32nh/JdL1+PSicowtNb0WFpn59GK8/lfD61bVtzguz7b3PBt74nxpv/Pw5po5Rg==",
+      "engines": {
+        "node": ">=8"
+      }
+    },
     "node_modules/statuses": {
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/statuses/-/statuses-2.0.1.tgz",
@@ -14902,9 +14910,12 @@
       }
     },
     "node_modules/type-fest": {
-      "version": "0.7.1",
+      "version": "4.10.3",
-      "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-0.7.1.tgz",
+      "resolved": "https://registry.npmjs.org/type-fest/-/type-fest-4.10.3.tgz",
-      "integrity": "sha512-Ne2YiiGN8bmrmJJEuTWTLJR32nh/JdL1+PSicowtNb0WFpn59GK8/lfD61bVtzguz7b3PBt74nxpv/Pw5po5Rg==",
+      "integrity": "sha512-JLXyjizi072smKGGcZiAJDCNweT8J+AuRxmPZ1aG7TERg4ijx9REl8CNhbr36RV4qXqL1gO1FF9HL8OkVmmrsA==",
+      "dev": true,
+      "optional": true,
+      "peer": true,
       "engines": {
         "node": ">=8"
       }

server/GameServer/Commands.lean

@@ -2,6 +2,9 @@ import GameServer.Helpers
 import GameServer.Inventory
 import GameServer.Options
 import GameServer.SaveData
+import GameServer.Hints
+import GameServer.Tactic.LetIntros
+import I18n
 
 open Lean Meta Elab Command
 
@@ -32,16 +35,17 @@ elab "Level" level:num : command => do
 
 /-- Define the title of the current game/world/level. -/
 elab "Title" t:str : command => do
+  let title ← t.getString.translate
   match ← getCurLayer with
-  | .Level => modifyCurLevel fun level => pure {level with title := t.getString}
+  | .Level => modifyCurLevel fun level => pure {level with title := title}
-  | .World => modifyCurWorld  fun world => pure {world with title := t.getString}
+  | .World => modifyCurWorld  fun world => pure {world with title := title}
   | .Game => modifyCurGame  fun game => pure {game with
       title := t.getString
-      tile := {game.tile with title := t.getString}}
+      tile := {game.tile with title := title}}
 
 /-- Define the introduction of the current game/world/level. -/
 elab "Introduction" t:str : command => do
-  let intro := t.getString
+  let intro ← t.getString.translate
   match ← getCurLayer with
   | .Level => modifyCurLevel fun level => pure {level with introduction := intro}
   | .World => modifyCurWorld  fun world => pure {world with introduction := intro}
@@ -49,7 +53,7 @@ elab "Introduction" t:str : command => do
 
 /-- Define the info of the current game. Used for e.g. credits -/
 elab "Info" t:str : command => do
-  let info:= t.getString
+  let info ← t.getString.translate
   match ← getCurLayer with
   | .Level =>
     logError "Can't use `Info` in a level!"
@@ -81,7 +85,7 @@ elab "Image" t:str : command => do
 /-- Define the conclusion of the current game or current level if some
 building a level. -/
 elab "Conclusion" t:str : command => do
-  let conclusion := t.getString
+  let conclusion ← t.getString.translate
   match ← getCurLayer with
   | .Level => modifyCurLevel fun level => pure {level with conclusion := conclusion}
   | .World => modifyCurWorld  fun world => pure {world with conclusion := conclusion}
@@ -94,13 +98,13 @@ elab "Prerequisites" t:str* : command => do
 
 /-- Short caption for the game (1 sentence) -/
 elab "CaptionShort" t:str : command => do
-  let caption := t.getString
+  let caption ← t.getString.translate
   modifyCurGame fun game => pure {game with
     tile := {game.tile with short := caption}}
 
 /-- More detailed description what the game is about (2-4 sentences). -/
 elab "CaptionLong" t:str : command => do
-  let caption := t.getString
+  let caption ← t.getString.translate
   modifyCurGame fun game => pure {game with
     tile := {game.tile with long := caption}}
 
@@ -141,6 +145,7 @@ TacticDoc rw "`rw` stands for rewrite, etc. "
  -/
 elab doc:docComment ? "TacticDoc" name:ident content:str ? : command => do
   let doc ← parseDocCommentLegacy doc content
+  let doc ← doc.translate
   modifyEnv (inventoryTemplateExt.addEntry · {
     type := .Tactic
     name := name.getId
@@ -165,6 +170,7 @@ The theorem/definition to have the same fully qualified name as in mathlib.
 elab doc:docComment ? "TheoremDoc" name:ident "as" displayName:str "in" category:str content:str ? :
     command => do
   let doc ← parseDocCommentLegacy doc content
+  let doc ← doc.translate
   modifyEnv (inventoryTemplateExt.addEntry · {
     type := .Lemma
     name := name.getId
@@ -194,6 +200,7 @@ The theorem/definition to have the same fully qualified name as in mathlib.
  -/
 elab doc:docComment ? "DefinitionDoc" name:ident "as" displayName:str template:str ? : command => do
   let doc ← parseDocCommentLegacy doc template
+  let doc ← doc.translate
   modifyEnv (inventoryTemplateExt.addEntry · {
     type := .Definition
     name := name.getId,
@@ -340,6 +347,9 @@ elab doc:docComment ? attrs:Parser.Term.attributes ?
   let lvlIdx ← getCurLevelIdx
 
   let docContent ← parseDocComment doc
+  let docContent ← match docContent with
+  | none => pure none
+  | some d => d.translate
 
   -- Save the messages before evaluation of the proof.
   let initMsgs ← modifyGet fun st => (st.messages, { st with messages := {} })
@@ -355,36 +365,38 @@ elab doc:docComment ? attrs:Parser.Term.attributes ?
     collectUsedInventory proof
   | _ => throwError "expected `:=`"
 
+  -- extract the `tacticSeq` from `val` in order to add `let_intros` in front.
+  -- TODO: don't understand meta-programming enough to avoid having `let_intros`
+  -- duplicated three times below…
+  let tacticStx : TSyntax `Lean.Parser.Tactic.tacticSeq := match val with
+  | `(Parser.Command.declVal| := by $proof) => proof
+  | _ => panic "expected `:= by`"
+
   -- Add theorem to context.
   match statementName with
   | some name =>
     let env ← getEnv
-
     let fullName := (← getCurrNamespace) ++ name.getId
-
     if env.contains fullName then
       let origType := (env.constants.map₁.find! fullName).type
       -- TODO: Check if `origType` agrees with `sig` and output `logInfo` instead of `logWarning`
       -- in that case.
       logWarningAt name (m!"Environment already contains {fullName}! Only the existing " ++
       m!"statement will be available in later levels:\n\n{origType}")
-      let thmStatement ← `(command| $[$doc]? $[$attrs:attributes]? theorem $defaultDeclName $sig $val)
+      let thmStatement ← `(command| $[$doc]? $[$attrs:attributes]? theorem $defaultDeclName $sig := by {let_intros; $(⟨tacticStx⟩)})
       elabCommand thmStatement
       -- Check that statement has a docs entry.
       checkInventoryDoc .Lemma name (name := fullName) (template := docContent)
-
     else
-      let thmStatement ← `(command| $[$doc]? $[$attrs:attributes]? theorem $name $sig $val)
+      let thmStatement ← `(command| $[$doc]? $[$attrs:attributes]? theorem $name $sig := by {let_intros; $(⟨tacticStx⟩)})
       elabCommand thmStatement
       -- Check that statement has a docs entry.
       checkInventoryDoc .Lemma name (name := fullName) (template := docContent)
-
   | none =>
-    let thmStatement ← `(command| $[$doc]? $[$attrs:attributes]? theorem $defaultDeclName $sig $val)
+    let thmStatement ← `(command| $[$doc]? $[$attrs:attributes]? theorem $defaultDeclName $sig := by {let_intros; $(⟨tacticStx⟩)})
     elabCommand thmStatement
 
   let msgs := (← get).messages
-
   let mut hints := #[]
   let mut nonHintMsgs := #[]
   for msg in msgs.msgs do
@@ -396,12 +408,41 @@ elab doc:docComment ? attrs:Parser.Term.attributes ?
         .nest hidden $
         .compose (.ofGoal text) (.ofGoal goal) := msg.data then
       let hint ← liftTermElabM $ withMCtx ctx.mctx $ withLCtx ctx.lctx #[] $ withEnv ctx.env do
+
+        let goalDecl ← goal.getDecl
+        let fvars := goalDecl.lctx.decls.toArray.filterMap id |> Array.map (·.fvarId)
+
+        -- NOTE: This code about `hintFVarsNames` is duplicated from `RpcHandlers`
+        -- where the variable bijection is constructed, and they
+        -- need to be matching.
+        -- NOTE: This is a bit a hack of somebody who does not know how meta-programming works.
+        -- All we want here is a list of `userNames` for the `FVarId`s in `hintFVars`...
+        -- and we wrap them in `«{}»` here since I don't know how to do it later.
+        let mut hintFVarsNames : Array Expr := #[]
+        for fvar in fvars do
+          let name₁ ← fvar.getUserName
+          hintFVarsNames := hintFVarsNames.push <| Expr.fvar ⟨s!"«\{{name₁}}»"⟩
+
+        let text ← instantiateMVars (mkMVar text)
+
+        -- Evaluate the text in the `Hint`'s context to get the old variable names.
+        let rawText := (← GameServer.evalHintMessage text) hintFVarsNames
+        let ctx₂ := {env := ← getEnv, mctx := ← getMCtx, lctx := ← getLCtx, opts := {}}
+        let rawText : String ← (MessageData.withContext ctx₂ rawText).toString
+
         return {
           goal := ← abstractCtx goal
-          text := ← instantiateMVars (mkMVar text)
+          text := text
+          rawText := rawText
           strict := strict == 1
           hidden := hidden == 1
         }
+
+      -- Note: The current setup for hints is a bit convoluted, but for now we need to
+      -- send the text once through i18n to register it in the env extension.
+      -- This could probably be rewritten once i18n works fully.
+      let _ ← hint.rawText.translate
+
       hints := hints.push hint
     else
       nonHintMsgs := nonHintMsgs.push msg
@@ -440,6 +481,8 @@ elab doc:docComment ? attrs:Parser.Term.attributes ?
 
 /-! # Hints -/
 
+open GameServer in
+
 /-- A tactic that can be used inside `Statement`s to indicate in which proof states players should
 see hints. The tactic does not affect the goal state.
 -/

server/GameServer/EnvExtensions.lean

@@ -1,7 +1,13 @@
 import GameServer.AbstractCtx
 import GameServer.Graph
+import GameServer.Hints
 
+open GameServer
 
+-- TODO: Is there a better place?
+/-- Keywords that the server should not consider as tactics. -/
+def GameServer.ALLOWED_KEYWORDS : List String :=
+  ["with", "fun", "at", "only", "by", "generalizing"]
 
 /-- The default game name if `Game "MyGame"` is not used. -/
 def defaultGameName: String := "MyGame"
@@ -18,22 +24,6 @@ defined in this file.
 
 open Lean
 
-/-! ## Hints -/
-
-/-- A hint to help the user with a specific goal state -/
-structure GoalHintEntry where
-  goal : AbstractCtxResult
-  /-- Text of the hint as an expression of type `Array Expr → MessageData` -/
-  text : Expr
-  /-- If true, then hint should be hidden and only be shown on player's request -/
-  hidden : Bool := false
-  /-- If true, then the goal must contain only the assumptions specified in `goal` and no others -/
-  strict : Bool := false
-
-instance : Repr GoalHintEntry := {
-  reprPrec := fun a n => reprPrec a.text n
-}
-
 /-! ## Inventory (documentation)
 
 The inventory contains documentation that the user can access.

server/GameServer/FileWorker.lean

@@ -4,6 +4,7 @@ import GameServer.Game
 import GameServer.ImportModules
 import GameServer.SaveData
 import GameServer.EnvExtensions
+import GameServer.Tactic.LetIntros
 
 namespace MyModule
 
@@ -122,7 +123,7 @@ partial def findForbiddenTactics (inputCtx : Parser.InputContext) (workerState :
     -- Atoms might be tactic names or other keywords.
     -- Note: We whitelisted known keywords because we cannot
     -- distinguish keywords from tactic names.
-    let allowed := ["with", "fun", "at", "only", "by", "to", "generalizing", "says"]
+    let allowed := GameServer.ALLOWED_KEYWORDS
     -- Ignore syntax elements that do not start with a letter or are listed above.
     if 0 < val.length ∧ val.data[0]!.isAlpha ∧ not (allowed.contains val) then
       -- Treat `simp?` and `simp!` like `simp`
@@ -169,15 +170,20 @@ partial def findForbiddenTactics (inputCtx : Parser.InputContext) (workerState :
       match theoremsAndDefs.find? (·.name == n) with
       | none =>
         -- Theorem will never be introduced in this game
-        addMessageByDifficulty info s!"You have not unlocked the theorem/definition '{n}' yet!"
+        addMessageByDifficulty info s!"The theorem/definition '{n}' is not available in this game!"
       | some thm =>
         -- Theorem is introduced at some point in the game.
         if thm.disabled then
           -- Theorem is disabled in this level.
           addMessageByDifficulty info s!"The theorem/definition '{n}' is disabled in this level!"
         else if thm.locked then
-          -- Theorem is still locked.
+          match workerState.inventory.find? (· == n.toString) with
-          addMessageByDifficulty info s!"You have not unlocked the theorem/definition '{n}' yet!"
+          | none =>
+            -- Theorem is still locked.
+            addMessageByDifficulty info s!"You have not unlocked the theorem/definition '{n}' yet!"
+          | some _ =>
+            -- Theorem is in the inventory, allow it.
+            pure ()
 
 where addMessageByDifficulty (info : SourceInfo) (s : MessageData) :=
   -- See `GameServer.FileWorker.WorkerState.difficulty`. Send nothing/warnings/errors
@@ -253,8 +259,11 @@ def compileProof (inputCtx : Parser.InputContext) (snap : Snapshot) (hasWidgets
           let tacticStx := (#[skip] ++ tacticStx.getArgs ++ #[done]).map (⟨.⟩)
           let tacticStx := ← `(Lean.Parser.Tactic.tacticSeq| $[$(tacticStx)]*)
 
+          -- Always call `let_intros` to get rid `let` statements in the goal.
+          -- This makes the experience for the user much nicer and allows for local
+          -- definitions in the exercise.
           let cmdStx ← `(command|
-            theorem the_theorem $(level.goal) := by {$(⟨tacticStx⟩)} )
+            theorem the_theorem $(level.goal) := by {let_intros; $(⟨tacticStx⟩)} )
           Elab.Command.elabCommandTopLevel cmdStx)
       cmdCtx cmdStateRef
   let postNew := (← tacticCacheNew.get).post
@@ -299,7 +308,7 @@ where
   private def publishIleanInfo (method : String) (m : DocumentMeta) (hOut : FS.Stream)
       (snaps : Array Snapshot) : IO Unit := do
     let trees := snaps.map fun snap => snap.infoTree
-    let references := findModuleRefs m.text trees (localVars := true)
+    let references ← findModuleRefs m.text trees (localVars := true) |>.toLspModuleRefs
     let param := { version := m.version, references : LeanIleanInfoParams }
     hOut.writeLspNotification { method, param }
 
@@ -386,60 +395,60 @@ def publishProofState (m : DocumentMeta) (snap : Snapshot) (initParams : Lsp.Ini
 
   hOut.writeLspNotification { method := "$/game/publishProofState", param }
 
-  /-- Checks whether game level has been completed and sends a notification to the client -/
+/-- Checks whether game level has been completed and sends a notification to the client -/
-  def publishGameCompleted (m : DocumentMeta) (hOut : FS.Stream) (snaps : Array Snapshot) : IO Unit := do
+def publishGameCompleted (m : DocumentMeta) (hOut : FS.Stream) (snaps : Array Snapshot) : IO Unit := do
-    -- check if there is any error or warning
+  -- check if there is any error or warning
-    for snap in snaps do
+  for snap in snaps do
-      if snap.diagnostics.any fun d => d.severity? == some .error ∨ d.severity? == some .warning
+    if snap.diagnostics.any fun d => d.severity? == some .error ∨ d.severity? == some .warning
-      then return
+    then return
-    let param := { uri := m.uri : GameCompletedParams}
+  let param := { uri := m.uri : GameCompletedParams}
-    hOut.writeLspNotification { method := "$/game/completed", param }
+  hOut.writeLspNotification { method := "$/game/completed", param }
 
-  /-- copied from `Lean.Server.FileWorker.nextCmdSnap`. -/
+/-- copied from `Lean.Server.FileWorker.nextCmdSnap`. -/
-  -- @[inherit_doc Lean.Server.FileWorker.nextCmdSnap] -- cannot inherit from private
+-- @[inherit_doc Lean.Server.FileWorker.nextCmdSnap] -- cannot inherit from private
-  private def nextCmdSnap (ctx : WorkerContext) (m : DocumentMeta) (cancelTk : CancelToken)
+private def nextCmdSnap (ctx : WorkerContext) (m : DocumentMeta) (cancelTk : CancelToken)
-      (gameWorkerState : WorkerState) (initParams : Lsp.InitializeParams) :
+    (gameWorkerState : WorkerState) (initParams : Lsp.InitializeParams) :
-      AsyncElabM (Option Snapshot) := do
+    AsyncElabM (Option Snapshot) := do
-    cancelTk.check
+  cancelTk.check
-    let s ← get
+  let s ← get
-    let .some lastSnap := s.snaps.back? | panic! "empty snapshots"
+  let .some lastSnap := s.snaps.back? | panic! "empty snapshots"
-    if lastSnap.isAtEnd then
+  if lastSnap.isAtEnd then
-      publishDiagnostics m lastSnap.diagnostics.toArray ctx.hOut
+    publishDiagnostics m lastSnap.diagnostics.toArray ctx.hOut
-      publishProgressDone m ctx.hOut
+    publishProgressDone m ctx.hOut
-      publishIleanInfoFinal m ctx.hOut s.snaps
+    publishIleanInfoFinal m ctx.hOut s.snaps
-      return none
+    return none
-    publishProgressAtPos m lastSnap.endPos ctx.hOut
+  publishProgressAtPos m lastSnap.endPos ctx.hOut
 
-    -- (modified part)
+  -- (modified part)
-    -- Make sure that there is at least one snap after the head snap, so that
+  -- Make sure that there is at least one snap after the head snap, so that
-    -- we can see the current goal even on an empty document
+  -- we can see the current goal even on an empty document
-    let couldBeEndSnap := s.snaps.size > 1
+  let couldBeEndSnap := s.snaps.size > 1
-    let snap ← compileProof m.mkInputContext lastSnap ctx.clientHasWidgets couldBeEndSnap
+  let snap ← compileProof m.mkInputContext lastSnap ctx.clientHasWidgets couldBeEndSnap
-      gameWorkerState initParams
+    gameWorkerState initParams
 
-    set { s with snaps := s.snaps.push snap }
+  set { s with snaps := s.snaps.push snap }
-    cancelTk.check
+  cancelTk.check
-    publishProofState m snap initParams ctx.hOut
+  -- publishProofState m snap initParams ctx.hOut
-    publishDiagnostics m snap.diagnostics.toArray ctx.hOut
+  publishDiagnostics m snap.diagnostics.toArray ctx.hOut
-    publishIleanInfoUpdate m ctx.hOut #[snap]
+  publishIleanInfoUpdate m ctx.hOut #[snap]
-    return some snap
+  return some snap
 
-  -- Copied from `Lean.Server.FileWorker.unfoldCmdSnaps` using our own `nextCmdSnap`.
+-- Copied from `Lean.Server.FileWorker.unfoldCmdSnaps` using our own `nextCmdSnap`.
-  @[inherit_doc Lean.Server.FileWorker.unfoldCmdSnaps]
+@[inherit_doc Lean.Server.FileWorker.unfoldCmdSnaps]
-  def unfoldCmdSnaps (m : DocumentMeta) (snaps : Array Snapshot) (cancelTk : CancelToken)
+def unfoldCmdSnaps (m : DocumentMeta) (snaps : Array Snapshot) (cancelTk : CancelToken)
-      (startAfterMs : UInt32) (gameWorkerState : WorkerState)
+    (startAfterMs : UInt32) (gameWorkerState : WorkerState)
-      : ReaderT WorkerContext IO (AsyncList ElabTaskError Snapshot) := do
+    : ReaderT WorkerContext IO (AsyncList ElabTaskError Snapshot) := do
-    let ctx ← read
+  let ctx ← read
-    let some headerSnap := snaps[0]? | panic! "empty snapshots"
+  let some headerSnap := snaps[0]? | panic! "empty snapshots"
-    if headerSnap.msgLog.hasErrors then
+  if headerSnap.msgLog.hasErrors then
-      publishProgressAtPos m headerSnap.beginPos ctx.hOut (kind := LeanFileProgressKind.fatalError)
+    publishProgressAtPos m headerSnap.beginPos ctx.hOut (kind := LeanFileProgressKind.fatalError)
-      publishIleanInfoFinal m ctx.hOut #[headerSnap]
+    publishIleanInfoFinal m ctx.hOut #[headerSnap]
-      return AsyncList.ofList [headerSnap]
+    return AsyncList.ofList [headerSnap]
-    else
+  else
-      publishIleanInfoUpdate m ctx.hOut snaps
+    publishIleanInfoUpdate m ctx.hOut snaps
-      return AsyncList.ofList snaps.toList ++ AsyncList.delayed (← EIO.asTask (ε := ElabTaskError) (prio := .dedicated) do
+    return AsyncList.ofList snaps.toList ++ AsyncList.delayed (← EIO.asTask (ε := ElabTaskError) (prio := .dedicated) do
-        IO.sleep startAfterMs
+      IO.sleep startAfterMs
-        AsyncList.unfoldAsync (nextCmdSnap ctx m cancelTk gameWorkerState ctx.initParams) { snaps })
+      AsyncList.unfoldAsync (nextCmdSnap ctx m cancelTk gameWorkerState ctx.initParams) { snaps })
 
 end Elab
 
@@ -503,6 +512,12 @@ def DocumentMeta.mkInputContext (doc : DocumentMeta) : Parser.InputContext where
   fileName := (System.Uri.fileUriToPath? doc.uri).getD doc.uri |>.toString
   fileMap  := default
 
+/-- `gameDir` and `module` were added.
+
+TODO: In general this resembles little similarity with the
+original code, and I don't know why...
+-/
+-- @[inherit_doc Lean.Server.FileWorker.compileHeader]
 def compileHeader (m : DocumentMeta) (hOut : FS.Stream) (opts : Options) (hasWidgets : Bool)
     (gameDir : String) (module : Name):
     IO (Syntax × Task (Except Error (Snapshot × SearchPath))) := do
@@ -538,7 +553,7 @@ def compileHeader (m : DocumentMeta) (hOut : FS.Stream) (opts : Options) (hasWid
     let cmdState := Elab.Command.mkState headerEnv {} opts
     let cmdState := { cmdState with infoState := {
       enabled := true
-      trees := #[Elab.InfoTree.context ({
+      trees := #[Elab.InfoTree.context (.commandCtx {
         env     := headerEnv
         fileMap := m.text
         ngen    := { namePrefix := `_worker }
@@ -555,7 +570,7 @@ def compileHeader (m : DocumentMeta) (hOut : FS.Stream) (opts : Options) (hasWid
     let headerSnap := {
       beginPos := 0
       stx := headerStx
-      mpState := {}
+      mpState := {} -- was `headerParserState`
       cmdState := cmdState
       interactiveDiags := ← cmdState.messages.msgs.mapM (Widget.msgToInteractiveDiagnostic m.text · hasWidgets)
       tacticCache := (← IO.mkRef {})

server/GameServer/Helpers.lean

@@ -4,8 +4,6 @@ import Lean
 
 open Lean Meta Elab Command
 
-syntax hintArg := atomic(" (" (&"strict" <|> &"hidden") " := " withoutPosition(term) ")")
-
 /-! ## Doc Comment Parsing -/
 
 /-- Read a doc comment and get its content. Return `""` if no doc comment available. -/
@@ -85,23 +83,6 @@ def getStatementString (name : Name) : CommandElabM String := do
 syntax statementAttr := "(" &"attr" ":=" Parser.Term.attrInstance,* ")"
 -- TODO
 
-
-/-- Remove any spaces at the beginning of a new line -/
-partial def removeIndentation (s : String) : String :=
-  let rec loop (i : String.Pos) (acc : String) (removeSpaces := false) : String :=
-    let c := s.get i
-    let i := s.next i
-    if s.atEnd i then
-      acc.push c
-    else if removeSpaces && c == ' ' then
-      loop i acc (removeSpaces := true)
-    else if c == '\n' then
-      loop i (acc.push c) (removeSpaces := true)
-    else
-      loop i (acc.push c)
-  loop ⟨0⟩ ""
-
-
 /-! ## Loops in Graph-like construct
 
 TODO: Why are we not using graphs here but our own construct `HashMap Name (HashSet Name)`?

server/GameServer/Hints.lean

@@ -0,0 +1,54 @@
+import GameServer.AbstractCtx
+
+/-!
+This file contains anything related to the `Hint` tactic used to add hints to a game level.
+-/
+
+open Lean Meta Elab
+
+namespace GameServer
+
+syntax hintArg := atomic(" (" (&"strict" <|> &"hidden") " := " withoutPosition(term) ")")
+
+/-- A hint to help the user with a specific goal state -/
+structure GoalHintEntry where
+  goal : AbstractCtxResult
+  /-- Text of the hint as an expression of type `Array Expr → MessageData` -/
+  text : Expr
+  rawText : String
+  /-- If true, then hint should be hidden and only be shown on player's request -/
+  hidden : Bool := false
+  /-- If true, then the goal must contain only the assumptions specified in `goal` and no others -/
+  strict : Bool := false
+
+instance : Repr GoalHintEntry := {
+  reprPrec := fun a n => reprPrec a.text n
+}
+
+/-- For a hint `(hint : GoalHintEntry)` one uses `(← evalHintMessage hint.text) x`
+ where `(x : Array Expr)` contains the names of all the variables that should be inserted
+ in the text.
+
+ TODO: explain better. -/
+unsafe def evalHintMessageUnsafe : Expr → MetaM (Array Expr → MessageData) :=
+  evalExpr (Array Expr → MessageData)
+    (.forallE default (mkApp (mkConst ``Array [levelZero]) (mkConst ``Expr))
+      (mkConst ``MessageData) .default)
+
+@[implemented_by evalHintMessageUnsafe]
+def evalHintMessage : Expr → MetaM (Array Expr → MessageData) := fun _ => pure (fun _ => "")
+
+/-- Remove any spaces at the beginning of a new line -/
+partial def removeIndentation (s : String) : String :=
+  let rec loop (i : String.Pos) (acc : String) (removeSpaces := false) : String :=
+    let c := s.get i
+    let i := s.next i
+    if s.atEnd i then
+      acc.push c
+    else if removeSpaces && c == ' ' then
+      loop i acc (removeSpaces := true)
+    else if c == '\n' then
+      loop i (acc.push c) (removeSpaces := true)
+    else
+      loop i (acc.push c)
+  loop ⟨0⟩ ""

server/GameServer/InteractiveGoal.lean

@@ -146,7 +146,7 @@ def goalToInteractive (mvarId : MVarId) : MetaM InteractiveGoal := do
     return {
       hyps
       type := goalFmt
-      ctx := ⟨← Elab.ContextInfo.save⟩
+      ctx := ⟨{← Elab.CommandContextInfo.save with }⟩
       userName?
       goalPrefix := getGoalPrefix mvarDecl
       mvarId

server/GameServer/Inventory.lean

@@ -121,7 +121,7 @@ partial def collectUsedInventory (stx : Syntax) (acc : UsedInventory := {}) : Co
   | .atom _info val =>
     -- ignore syntax elements that do not start with a letter
     -- and ignore some standard keywords
-    let allowed := ["with", "fun", "at", "only", "by"]
+    let allowed := GameServer.ALLOWED_KEYWORDS
     if 0 < val.length ∧ val.data[0]!.isAlpha ∧ not (allowed.contains val) then
       let val := val.dropRightWhile (fun c => c == '!' || c == '?') -- treat `simp?` and `simp!` like `simp`
       return {acc with tactics := acc.tactics.insert val}

server/GameServer/RpcHandlers.lean

@@ -1,6 +1,7 @@
 import GameServer.EnvExtensions
 import GameServer.InteractiveGoal
 import Std.Data.Array.Init.Basic
+import GameServer.Hints
 
 open Lean
 open Server
@@ -103,14 +104,6 @@ def matchDecls (patterns : Array Expr) (fvars : Array Expr) (strict := true) (in
   then return some bij
   else return none
 
-unsafe def evalHintMessageUnsafe : Expr → MetaM (Array Expr → MessageData) :=
-  evalExpr (Array Expr → MessageData)
-    (.forallE default (mkApp (mkConst ``Array [levelZero]) (mkConst ``Expr))
-      (mkConst ``MessageData) .default)
-
-@[implemented_by evalHintMessageUnsafe]
-def evalHintMessage : Expr → MetaM (Array Expr → MessageData) := fun _ => pure (fun _ => "")
-
 open Meta in
 /-- Find all hints whose trigger matches the current goal -/
 def findHints (goal : MVarId) (m : DocumentMeta) (initParams : Lsp.InitializeParams) : MetaM (Array GameHint) := do
@@ -121,19 +114,53 @@ def findHints (goal : MVarId) (m : DocumentMeta) (initParams : Lsp.InitializePar
       openAbstractCtxResult hint.goal fun hintFVars hintGoal => do
         if let some fvarBij := matchExpr (← instantiateMVars $ hintGoal) (← instantiateMVars $ ← inferType $ mkMVar goal)
         then
-          let lctx := (← goal.getDecl).lctx
+
-          if let some bij ← matchDecls hintFVars lctx.getFVars (strict := hint.strict) (initBij := fvarBij)
+          -- NOTE: This code for `hintFVarsNames` is also duplicated in the
+          -- "Statement" command, where `hint.rawText` is created. They need to be matching.
+          -- NOTE: This is a bit a hack of somebody who does not know how meta-programming works.
+          -- All we want here is a list of `userNames` for the `FVarId`s in `hintFVars`...
+          -- and we wrap them in `«{}»` here since I don't know how to do it later.
+          let mut hintFVarsNames : Array Expr := #[]
+          for fvar in hintFVars do
+            let name₁ ← fvar.fvarId!.getUserName
+            hintFVarsNames := hintFVarsNames.push <| Expr.fvar ⟨s!"«\{{name₁}}»"⟩
+
+          let lctx := (← goal.getDecl).lctx -- the player's local context
+          if let some bij ← matchDecls hintFVars lctx.getFVars
+            (strict := hint.strict) (initBij := fvarBij)
           then
             let userFVars := hintFVars.map fun v => bij.forward.findD v.fvarId! v.fvarId!
+            -- Evaluate the text in the player's context to get the new variable names.
             let text := (← evalHintMessage hint.text) (userFVars.map Expr.fvar)
             let ctx := {env := ← getEnv, mctx := ← getMCtx, lctx := lctx, opts := {}}
             let text ← (MessageData.withContext ctx text).toString
-            return some { text := text, hidden := hint.hidden }
+
+            -- Here we map the goal's variable names to the player's variable names.
+            let mut varNames : Array <| Name × Name := #[]
+            for (fvar₁, fvar₂) in bij.forward.toArray do
+              -- get the `userName` of the fvar in the opened local context of the hint.
+              let name₁ ← fvar₁.getUserName
+              -- get the `userName` in the player's local context.
+              let name₂ := (lctx.get! fvar₂).userName
+              varNames := varNames.push (name₁, name₂)
+
+            return some {
+              text := text,
+              hidden := hint.hidden,
+              rawText := hint.rawText,
+              varNames := varNames }
+
           else return none
         else
           return none
     return hints
 
+def filterUnsolvedGoal (a : Array InteractiveDiagnostic) :
+    Array InteractiveDiagnostic :=
+  a.filter (fun d => match d.message with
+  | .append ⟨(.text x) :: _⟩ => x != "unsolved goals"
+  | _ => true)
+
 -- TODO: no need to have `RequestM`, just anything where `mut` works
 /-- Add custom diagnostics about whether the level is completed. -/
 def completionDiagnostics (goalCount : Nat) (prevGoalCount : Nat) (completed : Bool)
@@ -161,21 +188,20 @@ def completionDiagnostics (goalCount : Nat) (prevGoalCount : Nat) (completed : B
     else
       pure ()
   else if goalCount < prevGoalCount then
-    out := out.push {
+    -- If there is any errors, goals might vanish without being 'solved'
-      message := .text "intermediate goal solved! 🎉"
+    -- so showing the message "intermediate goal solved" would be confusing.
-      range := {
+    if (¬ (filterUnsolvedGoal startDiags).any (·.severity? == some .error)) then
-        start := pos
+      out := out.push {
-        «end» := pos
+        message := .text "intermediate goal solved! 🎉"
-        }
+        range := {
-      severity? := Lsp.DiagnosticSeverity.information
+          start := pos
-    }
+          «end» := pos
+          }
+        severity? := Lsp.DiagnosticSeverity.information
+      }
+
   return out
 
-def filterUnsolvedGoal (a : Array InteractiveDiagnostic) :
-    Array InteractiveDiagnostic :=
-  a.filter (fun d => match d.message with
-  | .append ⟨(.text x) :: _⟩ => x != "unsolved goals"
-  | _ => true)
 
 /-- Request that returns the goals at the end of each line of the tactic proof
 plus the diagnostics (i.e. warnings/errors) for the proof.
@@ -185,9 +211,6 @@ def getProofState (_ : Lsp.PlainGoalParams) : RequestM (RequestTask (Option Proo
   let rc ← readThe RequestContext
   let text := doc.meta.text
 
-  -- BUG: trimming here is a problem, since the snap might already be evaluated before
-  -- the trimming and then the positions don't match anymore :((
-
   withWaitFindSnap
     doc
     -- TODO (Alex): I couldn't find a good condition to find the correct snap. So we are looking

server/GameServer/SaveData.lean

@@ -1,8 +1,8 @@
 import GameServer.EnvExtensions
+import I18n
 
 open Lean Meta Elab Command
 
-
 /-! ## Copy images -/
 
 open IO.FS System FilePath in
@@ -59,6 +59,9 @@ def saveGameData (allItemsByType : HashMap InventoryType (HashSet Name))
 
   IO.FS.writeFile (path / inventoryFileName) (toString (toJson inventory))
 
+  -- write PO file for translation
+  I18n.createPOTemplate
+
 open GameData
 
 def loadData (f : System.FilePath) (α : Type) [FromJson α] : IO α := do

server/GameServer/Structures.lean

@@ -54,8 +54,17 @@ deriving RpcEncodable
 
 /-- A hint in the game at the corresponding goal. -/
 structure GameHint where
+  /-- The text with the variable names already inserted.
+
+  Note: This is in theory superfluous and will be completely replaced by `rawText`. We just left
+  it in for debugging for now. -/
   text : String
+  /-- Flag whether the hint should be hidden initially. -/
   hidden : Bool
+  /-- The text with the variables not inserted yet. -/
+  rawText : String
+  /-- The assignment of variable names in the `rawText` to the ones the player used. -/
+  varNames : Array <| Name × Name
 deriving FromJson, ToJson
 
 /-- Bundled `InteractiveGoal` together with an array of hints that apply at this stage. -/

server/GameServer/Tactic/LetIntros.lean

@@ -0,0 +1,65 @@
+import Lean.Elab.Binders
+import Lean.Elab.Tactic.Basic
+import Lean.Meta.Tactic.Intro
+
+/-!
+# `let_intros` Tactic
+
+`let_intros` is a weaker form of `intros` aimed to only introduce `let` statements,
+but not for example `∀`-binders.
+-/
+
+namespace GameServer
+
+open Lean Meta Elab Parser Tactic
+
+/--
+Copied from `Lean.Meta.getIntrosSize`.
+-/
+private partial def getLetIntrosSize : Expr → Nat
+  -- | .forallE _ _ b _ => getLetIntrosSize b + 1
+  | .letE _ _ _ b _  => getLetIntrosSize b + 1
+  | .mdata _ b       => getLetIntrosSize b
+  | e                =>
+    if let some (_, _, _, b) := e.letFun? then
+      getLetIntrosSize b + 1
+    else
+      0
+
+/--
+Copied and from `Lean.MVarId.intros`.
+-/
+def _root_.Lean.MVarId.letIntros (mvarId : MVarId) : MetaM (Array FVarId × MVarId) := do
+  let type ← mvarId.getType
+  let type ← instantiateMVars type
+  let n := getLetIntrosSize type
+  if n == 0 then
+    return (#[], mvarId)
+  else
+    -- `introNP` preserves the binder names
+    mvarId.introNP n
+
+/--
+`let_intros` introduces all `let` statements that are preceeding the proof. Concretely
+it does a subset of what `intros` does.
+
+If names are provided, it will introduce as many `let` statements as there are names.
+-/
+syntax (name := letIntros) "let_intros" : tactic
+-- (ppSpace colGt (ident <|> hole))*
+
+#check letIntros
+
+@[tactic letIntros] def evalLetIntros : Tactic := fun stx => do
+  match stx with
+  | `(tactic| let_intros) => liftMetaTactic fun mvarId => do
+    let (_, mvarId) ← mvarId.letIntros
+    return [mvarId]
+  -- | `(tactic| let_intros $ids*) => do
+  --   let fvars ← liftMetaTacticAux fun mvarId => do
+  --     let (fvars, mvarId) ← mvarId.introN ids.size (ids.map getNameOfIdent').toList
+  --     return (fvars, [mvarId])
+  --   withMainContext do
+  --     for stx in ids, fvar in fvars do
+  --       Term.addLocalVarInfo stx (mkFVar fvar)
+  | _ => throwUnsupportedSyntax

server/lake-manifest.json

@@ -4,10 +4,19 @@
  [{"url": "https://github.com/leanprover/std4.git",
    "type": "git",
    "subDir": null,
-   "rev": "08ec2584b1892869e3a5f4122b029989bcb4ca79",
+   "rev": "a7543d1a6934d52086971f510e482d743fe30cf3",
    "name": "std",
    "manifestFile": "lake-manifest.json",
-   "inputRev": "v4.5.0",
+   "inputRev": "v4.6.0",
+   "inherited": false,
+   "configFile": "lakefile.lean"},
+  {"url": "https://github.com/hhu-adam/lean-i18n.git",
+   "type": "git",
+   "subDir": null,
+   "rev": "c5b84feffb28dbd5b1ac74b3bf63271296fabfa5",
+   "name": "i18n",
+   "manifestFile": "lake-manifest.json",
+   "inputRev": "v4.6.0",
    "inherited": false,
    "configFile": "lakefile.lean"}],
  "name": "GameServer",

server/lakefile.lean

@@ -4,11 +4,11 @@ open Lake DSL
 package GameServer
 
 -- Using this assumes that each dependency has a tag of the form `v4.X.0`.
-def leanVersion : String := s!"v{Lean.versionString}"
+-- def leanVersion : String := s!"v{Lean.versionString}"
+def leanVersion := "v4.6.0" -- TODO
 
 require std from git "https://github.com/leanprover/std4.git" @ leanVersion
-
+require i18n from git "https://github.com/hhu-adam/lean-i18n.git" @ leanVersion
--- require importGraph from git "https://github.com/leanprover-community/import-graph" @ leanVersion
 
 lean_lib GameServer
 

server/lean-toolchain

@@ -1 +1 @@
-leanprover/lean4:v4.5.0
+leanprover/lean4:v4.6.1

server/test/let_intros.lean

@@ -0,0 +1,17 @@
+import GameServer.Tactic.LetIntros
+
+set_option linter.unusedVariables false in
+
+example (f : Nat) :
+    let f := fun x ↦ x + 1
+    let g : Nat → Nat := fun y ↦ y
+    ∀ x : Nat, x ≤ f x := by
+  let_intros
+  /-
+  f✝ : Nat
+  f : Nat → Nat := fun x => x + 1
+  g : Nat → Nat := fun y => y
+  ⊢ ∀ (x : Nat), x ≤ f x
+  -/
+  intro x
+  exact Nat.le_succ x

tsconfig.json

@@ -11,6 +11,10 @@
     "downlevelIteration": true,
     "experimentalDecorators": true,
     "allowSyntheticDefaultImports": true,
+    "lib": [
+      "ES2021.String",
+      "DOM"
+    ]
   },
   "exclude": ["server", "relay"]
 }