Add matching-brackets exercise (#96)

* Add matching-brackets exercise

* Replace `when` with `if` for nextChar

config.json

@@ -255,6 +255,14 @@
         "prerequisites": [],
         "difficulty": 3
       },
+      {
+        "slug": "matching-brackets",
+        "name": "Matching Brackets",
+        "uuid": "5c7dbb9d-8816-4bbb-ba33-057ecf4f6329",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "pangram",
         "name": "Pangram",

exercises/practice/matching-brackets/.docs/instructions.md

@@ -0,0 +1,5 @@
+# Instructions
+
+Given a string containing brackets `[]`, braces `{}`, parentheses `()`, or any combination thereof, verify that any and all pairs are matched and nested correctly.
+Any other characters should be ignored.
+For example, `"{what is (42)}?"` is balanced and `"[text}"` is not.

exercises/practice/matching-brackets/.docs/introduction.md

@@ -0,0 +1,8 @@
+# Introduction
+
+You're given the opportunity to write software for the Bracketeer™, an ancient but powerful mainframe.
+The software that runs on it is written in a proprietary language.
+Much of its syntax is familiar, but you notice _lots_ of brackets, braces and parentheses.
+Despite the Bracketeer™ being powerful, it lacks flexibility.
+If the source code has any unbalanced brackets, braces or parentheses, the Bracketeer™ crashes and must be rebooted.
+To avoid such a scenario, you start writing code that can verify that brackets, braces, and parentheses are balanced before attempting to run it on the Bracketeer™.

exercises/practice/matching-brackets/.meta/Example.roc

@@ -0,0 +1,25 @@
+module [isPaired]
+
+isPaired : Str -> Bool
+isPaired = \string ->
+    isOpen = \c -> c == '[' || c == '(' || c == '{'
+    isClose = \c -> c == ']' || c == ')' || c == '}'
+    isMatch = \pair -> pair == ('[', ']') || pair == ('(', ')') || pair == ('{', '}')
+    help = \openBrackets, remainingChars ->
+        when remainingChars is
+            [] -> List.isEmpty openBrackets # ok or missing closing bracket
+            [nextChar, .. as restChars] ->
+                if isOpen nextChar then
+                    help (openBrackets |> List.append nextChar) restChars
+                else if isClose nextChar then
+                    when openBrackets is
+                        [] -> Bool.false # missing opening bracket
+                        [.. as previousOpens, lastOpen] ->
+                            if isMatch (lastOpen, nextChar) then
+                                help previousOpens restChars
+                            else
+                                Bool.false # mismatching brackets
+                else
+                    help openBrackets restChars
+
+    help [] (string |> Str.toUtf8)

exercises/practice/matching-brackets/.meta/config.json

@@ -0,0 +1,18 @@
+{
+  "authors": [
+    "ageron"
+  ],
+  "files": {
+    "solution": [
+      "MatchingBrackets.roc"
+    ],
+    "test": [
+      "matching-brackets-test.roc"
+    ],
+    "example": [
+      ".meta/Example.roc"
+    ]
+  },
+  "blurb": "Make sure the brackets and braces all match.",
+  "source": "Ginna Baker"
+}

exercises/practice/matching-brackets/.meta/template.j2

@@ -0,0 +1,13 @@
+{%- import "generator_macros.j2" as macros with context -%}
+{{ macros.canonical_ref() }}
+{{ macros.header() }}
+
+import {{ exercise | to_pascal }} exposing [{{ cases[0]["property"] | to_camel }}]
+
+{% for case in cases -%}
+# {{ case["description"] }}
+expect
+    result = {{ case["input"]["value"] | to_roc }} |> {{ case["property"] | to_camel }}
+    result == {{ case["expected"] | to_roc }}
+
+{% endfor %}

exercises/practice/matching-brackets/.meta/tests.toml

@@ -0,0 +1,70 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[81ec11da-38dd-442a-bcf9-3de7754609a5]
+description = "paired square brackets"
+
+[287f0167-ac60-4b64-8452-a0aa8f4e5238]
+description = "empty string"
+
+[6c3615a3-df01-4130-a731-8ef5f5d78dac]
+description = "unpaired brackets"
+
+[9d414171-9b98-4cac-a4e5-941039a97a77]
+description = "wrong ordered brackets"
+
+[f0f97c94-a149-4736-bc61-f2c5148ffb85]
+description = "wrong closing bracket"
+
+[754468e0-4696-4582-a30e-534d47d69756]
+description = "paired with whitespace"
+
+[ba84f6ee-8164-434a-9c3e-b02c7f8e8545]
+description = "partially paired brackets"
+
+[3c86c897-5ff3-4a2b-ad9b-47ac3a30651d]
+description = "simple nested brackets"
+
+[2d137f2c-a19e-4993-9830-83967a2d4726]
+description = "several paired brackets"
+
+[2e1f7b56-c137-4c92-9781-958638885a44]
+description = "paired and nested brackets"
+
+[84f6233b-e0f7-4077-8966-8085d295c19b]
+description = "unopened closing brackets"
+
+[9b18c67d-7595-4982-b2c5-4cb949745d49]
+description = "unpaired and nested brackets"
+
+[a0205e34-c2ac-49e6-a88a-899508d7d68e]
+description = "paired and wrong nested brackets"
+
+[1d5c093f-fc84-41fb-8c2a-e052f9581602]
+description = "paired and wrong nested brackets but innermost are correct"
+
+[ef47c21b-bcfd-4998-844c-7ad5daad90a8]
+description = "paired and incomplete brackets"
+
+[a4675a40-a8be-4fc2-bc47-2a282ce6edbe]
+description = "too many closing brackets"
+
+[a345a753-d889-4b7e-99ae-34ac85910d1a]
+description = "early unexpected brackets"
+
+[21f81d61-1608-465a-b850-baa44c5def83]
+description = "early mismatched brackets"
+
+[99255f93-261b-4435-a352-02bdecc9bdf2]
+description = "math expression"
+
+[8e357d79-f302-469a-8515-2561877256a1]
+description = "complex latex expression"

exercises/practice/matching-brackets/MatchingBrackets.roc

@@ -0,0 +1,5 @@
+module [isPaired]
+
+isPaired : Str -> Bool
+isPaired = \string ->
+    crash "Please implement the 'isPaired' function"

exercises/practice/matching-brackets/matching-brackets-test.roc

@@ -0,0 +1,112 @@
+# These tests are auto-generated with test data from:
+# https://github.com/exercism/problem-specifications/tree/main/exercises/matching-brackets/canonical-data.json
+# File last updated on 2024-09-16
+app [main] {
+    pf: platform "https://github.com/roc-lang/basic-cli/releases/download/0.15.0/SlwdbJ-3GR7uBWQo6zlmYWNYOxnvo8r6YABXD-45UOw.tar.br",
+}
+
+main =
+    Task.ok {}
+
+import MatchingBrackets exposing [isPaired]
+
+# paired square brackets
+expect
+    result = "[]" |> isPaired
+    result == Bool.true
+
+# empty string
+expect
+    result = "" |> isPaired
+    result == Bool.true
+
+# unpaired brackets
+expect
+    result = "[[" |> isPaired
+    result == Bool.false
+
+# wrong ordered brackets
+expect
+    result = "}{" |> isPaired
+    result == Bool.false
+
+# wrong closing bracket
+expect
+    result = "{]" |> isPaired
+    result == Bool.false
+
+# paired with whitespace
+expect
+    result = "{ }" |> isPaired
+    result == Bool.true
+
+# partially paired brackets
+expect
+    result = "{[])" |> isPaired
+    result == Bool.false
+
+# simple nested brackets
+expect
+    result = "{[]}" |> isPaired
+    result == Bool.true
+
+# several paired brackets
+expect
+    result = "{}[]" |> isPaired
+    result == Bool.true
+
+# paired and nested brackets
+expect
+    result = "([{}({}[])])" |> isPaired
+    result == Bool.true
+
+# unopened closing brackets
+expect
+    result = "{[)][]}" |> isPaired
+    result == Bool.false
+
+# unpaired and nested brackets
+expect
+    result = "([{])" |> isPaired
+    result == Bool.false
+
+# paired and wrong nested brackets
+expect
+    result = "[({]})" |> isPaired
+    result == Bool.false
+
+# paired and wrong nested brackets but innermost are correct
+expect
+    result = "[({}])" |> isPaired
+    result == Bool.false
+
+# paired and incomplete brackets
+expect
+    result = "{}[" |> isPaired
+    result == Bool.false
+
+# too many closing brackets
+expect
+    result = "[]]" |> isPaired
+    result == Bool.false
+
+# early unexpected brackets
+expect
+    result = ")()" |> isPaired
+    result == Bool.false
+
+# early mismatched brackets
+expect
+    result = "{)()" |> isPaired
+    result == Bool.false
+
+# math expression
+expect
+    result = "(((185 + 223.85) * 15) - 543)/2" |> isPaired
+    result == Bool.true
+
+# complex latex expression
+expect
+    result = "\\left(\\begin{array}{cc} \\frac{1}{3} & x\\\\ \\mathrm{e}^{x} &... x^2 \\end{array}\\right)" |> isPaired
+    result == Bool.true
+