Updates builtin type Map so that it stores Maybes in its nodes. by In-Veritas · Pull Request #743 · HigherOrderCO/Bend

In-Veritas · 2024-12-07T18:38:29Z

Summary of Changes

The following updates have been made to builtins.bend:

New/Updated Types and Functions

1. `Maybe`

New type definition:
```
type Maybe(T):
  Some {val: T}
  None
```

2. `Map`

Updated type definition:
```
type Map(T):
  Node {value: Maybe(T), ~left: Map(T), ~right: Map(T)}
  Leaf
```
Now, every Node stores a Maybe type to explicitly represent the presence or absence of a value.
Updated/added functions:
- Maybe/unwrap: Retrieves the value inside Maybe/Some
- Map/set: Inserts or updates a value in the map.
- Map/get: Retrieves a value from the map, returning a Maybe type.
- Map/map: Applies a function to each value in the map.
- Map/contains: Checks whether a key exists in the map.
- Map/get_check: Retrieves a value and performs additional validation.

Why remove unreachable() from Map nodes?

You cannot see which elements are in the Map, nor can you perform a fold operation on the Map to, for example, return a list of values or map each value. Since the stored elements are not usable for anything, it is not possible to use this structure to determine whether a given element is present in the map or not.
The unreachable() function incorrectly ignores type check and can often cause bugs where the type isn't checked for an entire branch altogether.
When checking the results of a program, receiving * does not tell you whether you merely hit an unused node, or if another function called unreachable().

Tests

Tests for the new functions have been added at Bend/tests/golden_tests/prelude

Documentation update

Partially updates documentation adding a section for the Maybe type and new Map functions

nicolas-abril

Why are you changing the Map type? You didn't even mention that in the PR.

Also please update the PR name to something more succint, its a bit confusing.

I'm not against having Bool in the prelude, but we don't really need it for anything builtin.

tests/builtin_Map_tests.bend

examples/example_fun.bend

examples/parallel_and.bend

src/fun/builtins.bend

tests/golden_tests/compile_file_o_all/match_adt_non_exhaustive.bend

tests/snapshots/encode_pattern_match__match_adt_unscoped_lambda.bend.snap

tests/snapshots/run_file__nested_map_get.bend.snap

tests/snapshots/run_file__nested_map_set.bend.snap

tests/snapshots/run_file__unbound_wrap.bend.snap

…CO#743

examples/parallel_and.bend

src/fun/builtins.bend

nicolas-abril · 2024-12-16T18:13:43Z

src/fun/builtins.bend

+      return (unreachable(), map)
+
+# Checks if a node has a value on a given key, returning Maybe/Some if it does, Maybe/None otherwise
+def Map/get_check (map: Map(T), key: u24) -> (Map(T), Maybe(T)):


get_check is not a great name. I prefer get_checked but it's also not great.

get also gets the node

get_wrapped?

src/fun/builtins.bend

tests/golden_tests/run_file/mixed_syntax.bend

tests/golden_tests/run_file/unscoped_never_used.bend

tests/snapshots/run_file__nested_map_get.bend.snap

tests/snapshots/run_file__nested_map_set.bend.snap

tests/golden_tests.rs

nicolas-abril · 2024-12-18T09:07:38Z

src/fun/builtins.bend

+      return (unreachable(), map)
+
+# Checks if a node has a value on a given key, returning Maybe/Some if it does, Maybe/None otherwise
+def Map/get_check (map: Map(T), key: u24) -> (Map(T), Maybe(T)):


get also gets the node

tests/golden_tests/prelude/map_contains_test.bend

docs/builtins.md

examples/example_fun.bend

tests/snapshots/prelude__builtin_Map_tests.bend.snap

tests/snapshots/prelude__get_values_from_map.bend.snap

nicolas-abril

I'll trust the tests are correct

tests/snapshots/prelude__map_tests.bend.snap

nicolas-abril

Looks good, good job

nicolas-abril · 2024-12-20T20:24:12Z

I think a new Rust version is messing with the checks, I'll fix it don't worry

nicolas-abril · 2024-12-23T22:12:03Z

Can you rebase and try again?
It should be fixed on the current main branch

…as the Maybe type Updates builtin type Map so that it stores Maybes in its nodes. Implement builtin type Map, and its corresponding functions, as well as the Maybe type Updates builtin type Map so that it stores Maybes in its nodes. Changes made on 09-12-2024, includes fixing requests from HigherOrderCO#743 Fixes based on PR review Partially updates doc and follows requests from PR review Fixes documentation, makes tests return simpler values, deletes useless snapshot Removes map_tests.bend.snap

nicolas-abril requested changes Dec 7, 2024

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In-Veritas changed the title ~~Updates builtin type Map, and its corresponding functions to the imp syntax, and adds types Bool and Maybe to builtins~~ Updates builtin type Map so that it stores Maybes in its notes. Dec 9, 2024

In-Veritas changed the title ~~Updates builtin type Map so that it stores Maybes in its notes.~~ Updates builtin type Map so that it stores Maybes in its nodes. Dec 9, 2024

In-Veritas added a commit to In-Veritas/Bend that referenced this pull request Dec 16, 2024

Changes made on 09-12-2024, includes fixing requests from HigherOrder…

6354a5e

…CO#743

In-Veritas requested a review from nicolas-abril December 16, 2024 18:09

nicolas-abril requested changes Dec 16, 2024

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nicolas-abril requested changes Dec 18, 2024

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In-Veritas requested a review from nicolas-abril December 20, 2024 17:49

nicolas-abril requested changes Dec 20, 2024

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In-Veritas requested a review from nicolas-abril December 20, 2024 19:23

nicolas-abril requested changes Dec 20, 2024

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tests/snapshots/prelude__map_tests.bend.snap Outdated Show resolved Hide resolved

nicolas-abril approved these changes Dec 20, 2024

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In-Veritas force-pushed the main branch from b454833 to 7048390 Compare December 26, 2024 14:38

nicolas-abril approved these changes Dec 26, 2024

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Rebases in order to pass tests

88db4e4

nicolas-abril added this pull request to the merge queue Dec 26, 2024

Merged via the queue into HigherOrderCO:main with commit a52cce7 Dec 26, 2024
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In-Veritas commented Dec 7, 2024 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary of Changes

New/Updated Types and Functions

1. Maybe

2. Map

Why remove unreachable() from Map nodes?

Tests

Documentation update

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In-Veritas commented Dec 7, 2024 •

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1. `Maybe`

2. `Map`