the next generation of the in-browser educational proof assistant
it is substDeBruijn
+34
-34
+34
-34
src/HOTerm.res
+34
-34
src/HOTerm.res
···
217
217
s->Map.set(schematic, term)
218
218
s
219
219
}
220
+
let rec substDeBruijn = (term: t, substs: array<t>, ~from: int=0) =>
221
+
switch term {
222
+
| Symbol(_) => term
223
+
| Var({idx: var}) =>
224
+
if var < from {
225
+
term
226
+
} else if var - from < Array.length(substs) && var - from >= 0 {
227
+
Option.getUnsafe(substs[var - from])
228
+
} else {
229
+
Var({idx: var - Array.length(substs)})
230
+
}
231
+
| Schematic({schematic, allowed}) =>
232
+
Schematic({
233
+
schematic,
234
+
allowed: Array.filterMap(allowed, i =>
235
+
if i < from + Array.length(substs) {
236
+
None
237
+
} else {
238
+
Some(i - (from + Array.length(substs)))
239
+
}
240
+
),
241
+
})
242
+
| Lam({name, body}) =>
243
+
Lam({
244
+
name,
245
+
body: substDeBruijn(body, substs->Array.map(term => upshift(term, 1)), ~from=from + 1),
246
+
})
247
+
| App({func, arg}) =>
248
+
App({
249
+
func: substDeBruijn(func, substs, ~from),
250
+
arg: substDeBruijn(arg, substs, ~from),
251
+
})
252
+
}
220
253
let rec lam = (amount: int, term: t): t =>
221
254
if amount <= 0 {
222
255
term
···
240
273
switch term {
241
274
| App({func, arg}) =>
242
275
switch reduce(func) {
243
-
| Lam({body}) => reduce(downshift(substitute(body, singletonSubst(0, upshift(arg, 1))), 1))
276
+
| Lam({body}) => reduce(downshift(substDeBruijn(body, [upshift(arg, 1)], ~from=0), 1))
244
277
| func => App({func, arg})
245
278
}
246
279
| term => term
···
342
375
| Some(s) => [s]
343
376
}
344
377
}
345
-
let rec substDeBruijn = (term: t, substs: array<t>, ~from: int=0) =>
346
-
switch term {
347
-
| Symbol(_) => term
348
-
| Var({idx: var}) =>
349
-
if var < from {
350
-
term
351
-
} else if var - from < Array.length(substs) && var - from >= 0 {
352
-
Option.getUnsafe(substs[var - from])
353
-
} else {
354
-
Var({idx: var - Array.length(substs)})
355
-
}
356
-
| Schematic({schematic, allowed}) =>
357
-
Schematic({
358
-
schematic,
359
-
allowed: Array.filterMap(allowed, i =>
360
-
if i < from + Array.length(substs) {
361
-
None
362
-
} else {
363
-
Some(i - (from + Array.length(substs)))
364
-
}
365
-
),
366
-
})
367
-
| Lam({name, body}) =>
368
-
Lam({
369
-
name,
370
-
body: substDeBruijn(body, substs->Array.map(term => upshift(term, 1)), ~from),
371
-
})
372
-
| App({func, arg}) =>
373
-
App({
374
-
func: substDeBruijn(func, substs, ~from),
375
-
arg: substDeBruijn(arg, substs, ~from),
376
-
})
377
-
}
378
378
let place = (x: int, ~scope: array<string>) => Schematic({
379
379
schematic: x,
380
380
allowed: Array.fromInitializer(~length=Array.length(scope), i => i),