Add several pairs-related methods #3617

d-torrance · 2024-12-18T15:48:21Z

We add pairs for any class with an iterator method as well as applyPairs, scanPairs, and selectPairs for non-hash tables. These are just shortcuts for apply(pairs ...), scan(pairs ...), and select(pairs ...).

i1 : take(pairs Iterator(() -> 5), 4)

o1 = {(0, 5), (1, 5), (2, 5), (3, 5)}

o1 : List

i2 : applyPairs({2, 4, 6}, (i, x) -> x^i)

o2 = (1, 4, 36)

o2 : Sequence

i3 : scanPairs({2, 4, 6}, (i, x) -> print i^x)
0
1
64

i4 : selectPairs({2, 4, 6}, (i, x) -> even(i + x))

o4 = ((0, 2), (2, 6))

o4 : Sequence

selectPairs doesn't currently work for iterators since select is defined for them at top-level, and this is all done in the interpreter.

Closes: #3603

mahrud · 2024-12-20T04:22:33Z

M2/Macaulay2/d/actors3.d

+-- # typical value: applyPairs, BasicList, Function, List
+-- # typical value: applyPairs, Dictionary, Function, List
+-- # typical value: applyPairs, Thing, Function, Iterator


I think it would be better to list these closer to where they are handled (e.g. near mappairs or map. We don't currently do this, but I'd like to have locate also show the location of compiled functions in the interpreter (the location is stored in tvalues.m2 as a comment right now).

mahrud · 2024-12-20T04:26:09Z

M2/Macaulay2/packages/Macaulay2Doc/doc_tables.m2

 Outputs
-  L:List
+  L:{List, Iterator}


I think it might be better to separate the documentation of the iterator form, ideally using Synopsis.

Cool -- I didn't know about Synopsis! Definitely useful for stuff like this.

M2/Macaulay2/packages/Macaulay2Doc/functions/select-doc.m2

It's a pretty common error message

applyPairs(x, f) is the same as apply(pairs x, f)

scanPairs(x, f) is the same as scan(pairs x, f)

selectPairs(x, f) is the same as select(pairs x, f) Doesn't support iterators (yet) since select is defined for them at top-level.

Now specify that they take BasicList arguments and move from typicalvalues.m2. Also document missing function variant.

d-torrance · 2024-12-20T12:37:31Z

I added a few more commits updating hashTable to allow Sequence arguments, as suggested by the original title of #3619. This way, hashTable @@ pairs will work with Sequence objects.

mahrud

Looks good to me. I left some comments, but most of them are rather subjective and don't need to block merging.

mahrud · 2024-12-28T00:00:48Z

M2/Macaulay2/d/actors2.dd

+	 when r
+	 is s:Sequence do list(o.Class, s, o.Mutable)
+	 else buildErrorPacket("internal error; expected a sequence"))
+     else applyEE(getGlobalVariable(pairsIteratorS), e)); -- # typical value: pairs, Thing, Iterator


fwiw I think putting the typical value tag on its own line would be better.

mahrud · 2024-12-28T00:02:07Z

M2/Macaulay2/d/actors2.dd

+	 r := pairs(Expr(o.v));
+	 when r
+	 is s:Sequence do list(o.Class, s, o.Mutable)
+	 else buildErrorPacket("internal error; expected a sequence"))


when would pairs(Expr(o.v)) with o:List fail?

It shouldn't -- we should always get a sequence here. I don't expect we'll ever raise this error.

Hmm, unless pairs raises an error... I'll look into this more.

mahrud · 2024-12-28T00:07:52Z

M2/Macaulay2/d/actors3.d

@@ -2346,6 +2363,20 @@ scan(e:Expr):Expr := (
     else WrongNumArgs(2));
 setupfun("scan",scan);

+-- # typical value: scanPairs, Thing, Function, Nothing


Since this line is for readability of documentation and doesn't have to be literally true, I wonder if it would be useful to use a dummy Iterable class instead of Thing for things like this. I know that practically anything with an iterator method defined on it can be iterable, so it may cause some confusion.

mahrud · 2024-12-28T00:11:33Z

M2/Macaulay2/d/actors4.d

+-- # typical value: selectPairs, HashTable, Function, HashTable
+-- # typical value: selectPairs, ZZ, HashTable, Function, HashTable
 selectPairs(nval:int, obj:HashTable, f:Expr):Expr := (


I think at some point we need to decide on a convention about where to place these lines. I don't find placing both of these here particularly useful. To me it either means one of them should be defined on the top level, or one of them is in the wrong place.

mahrud · 2024-12-28T00:13:21Z

M2/Macaulay2/d/expr.d

 export WrongArgHashTable():Expr := WrongArg("a hash table");
 export WrongArgHashTable(n:int):Expr := WrongArg(n, "a hash table");
+export WrongArgImmutableHashTable():Expr := WrongArg("an immutable hash table");
+export WrongArgImmutableHashTable(n:int):Expr := WrongArg(n, "an immutable hash table");


Seems to me like WrongArgHashTable should say immutable hash table and we should have a WrongArgMutableHashTable which says mutable hash table.

d-torrance requested a review from mahrud December 18, 2024 15:48

d-torrance force-pushed the apply-pairs branch from 718cf4a to 709e641 Compare December 20, 2024 02:53

d-torrance mentioned this pull request Dec 20, 2024

pairs should always return a _list_ of sequences #3619

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mahrud reviewed Dec 20, 2024

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M2/Macaulay2/packages/Macaulay2Doc/functions/select-doc.m2 Outdated Show resolved Hide resolved

d-torrance added 9 commits December 20, 2024 07:34

Add pairs(Thing), which returns an Iterator

1208f56

Add WrongArgImmutableHashTable helper function in d directory

67f2ab5

It's a pretty common error message

Add applyPairs for non-hash tables

6348b0c

applyPairs(x, f) is the same as apply(pairs x, f)

Add scanPairs for non-hash tables

5a6a333

scanPairs(x, f) is the same as scan(pairs x, f)

Add selectPairs for non-hash table

2e43c71

selectPairs(x, f) is the same as select(pairs x, f) Doesn't support iterators (yet) since select is defined for them at top-level.

Make pairs(BasicList) return list of same class

a05d192

Move isFunction to util.d w/ similar functions and export

977dcd9

Add support for sequence arguments to hashTable

1c74996

Update hashTable methods

7f4070b

Now specify that they take BasicList arguments and move from typicalvalues.m2. Also document missing function variant.

d-torrance force-pushed the apply-pairs branch from 709e641 to 7f4070b Compare December 20, 2024 12:35

mahrud approved these changes Dec 28, 2024

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d-torrance merged commit e40e51d into Macaulay2:development Dec 28, 2024
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d-torrance mentioned this pull request Jan 17, 2025

applyPairs for lists #3603

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Add several pairs-related methods #3617

Add several pairs-related methods #3617

d-torrance commented Dec 18, 2024

mahrud Dec 20, 2024

mahrud Dec 20, 2024

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Add several pairs-related methods #3617

Add several pairs-related methods #3617

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