Set up prettier for markdown files (#2322)

.github/workflows/action-format.yml

@@ -6,7 +6,7 @@ on:
 
 jobs:
   format:
-    name: 'Format JSON'
+    name: 'Format'
     runs-on: ubuntu-22.04
     if: github.event.issue.pull_request != '' && contains(github.event.comment.body, '/format')
     steps:
@@ -89,6 +89,9 @@ jobs:
       - name: Format JSON files
         run: yarn format-json && ruby bin/format-array.rb
 
+      - name: Format Markdown files
+        run: yarn format-md
+
       - name: 'Commit formatted code'
         run: |
           # Check if there is nothing to commit (i.e. no formatting changes made)

.github/workflows/ci.yml

@@ -123,6 +123,24 @@ jobs:
           globs: |
             **/*.md
 
+      - name: Setup nodejs
+        uses: actions/setup-node@64ed1c7eab4cce3362f8c340dee64e5eaeef8f7c # v3.6.0
+        with:
+          node-version: 16
+          cache: "yarn"
+
+      - name: Install dependencies
+        run: yarn install
+
+      - name: Verify that markdown files are formatted correctly
+        run: |
+          yarn format-md
+          if ! git diff --quiet --exit-code; then
+            echo "please format the files with prettier, or apply the following changes:"
+            git diff
+            exit 1
+          fi
+
   check-links:
     name: Check links
     runs-on: ubuntu-latest

CODE_OF_CONDUCT.md

@@ -90,4 +90,4 @@ This policy was initially adopted from the Front-end London Slack community and
 A version history can be seen on [GitHub](https://github.com/exercism/website-copy/edit/main/pages/code_of_conduct.md).
 
 _This policy is a "living" document, and subject to refinement and expansion in the future.
-This policy applies to the Exercism website, the Exercism GitHub organization, any other Exercism-related communication channels (e.g.  Slack, Twitter, email) and any other Exercism entity or event._
+This policy applies to the Exercism website, the Exercism GitHub organization, any other Exercism-related communication channels (e.g. Slack, Twitter, email) and any other Exercism entity or event._

exercises/acronym/description.md

@@ -10,8 +10,8 @@ Punctuation is handled as follows: hyphens are word separators (like whitespace)
 
 For example:
 
-|Input|Output|
-|-|-|
-|As Soon As Possible|ASAP|
-|Liquid-crystal display|LCD|
-|Thank George It's Friday!|TGIF|
+| Input                     | Output |
+| ------------------------- | ------ |
+| As Soon As Possible       | ASAP   |
+| Liquid-crystal display    | LCD    |
+| Thank George It's Friday! | TGIF   |

exercises/affine-cipher/description.md

@@ -6,7 +6,7 @@ The affine cipher is a type of monoalphabetic substitution cipher.
 Each character is mapped to its numeric equivalent, encrypted with a mathematical function and then converted to the letter relating to its new numeric value.
 Although all monoalphabetic ciphers are weak, the affine cipher is much stronger than the atbash cipher, because it has many more keys.
 
-[//]: # ( monoalphabetic as spelled by Merriam-Webster, compare to polyalphabetic )
+[//]: # " monoalphabetic as spelled by Merriam-Webster, compare to polyalphabetic "
 
 ## Encryption
 
@@ -23,7 +23,7 @@ Where:
   For the Roman alphabet `m` is `26`.
 - `a` and `b` are integers which make the encryption key
 
-Values `a` and `m` must be *coprime* (or, *relatively prime*) for automatic decryption to succeed, i.e., they have number `1` as their only common factor (more information can be found in the [Wikipedia article about coprime integers][coprime-integers]).
+Values `a` and `m` must be _coprime_ (or, _relatively prime_) for automatic decryption to succeed, i.e., they have number `1` as their only common factor (more information can be found in the [Wikipedia article about coprime integers][coprime-integers]).
 In case `a` is not coprime to `m`, your program should indicate that this is an error.
 Otherwise it should encrypt or decrypt with the provided key.
 

exercises/all-your-base/description.md

@@ -14,20 +14,20 @@ Given a number in base **a**, represented as a sequence of digits, convert it to
 
 In positional notation, a number in base **b** can be understood as a linear combination of powers of **b**.
 
-The number 42, *in base 10*, means:
+The number 42, _in base 10_, means:
 
 `(4 * 10^1) + (2 * 10^0)`
 
-The number 101010, *in base 2*, means:
+The number 101010, _in base 2_, means:
 
 `(1 * 2^5) + (0 * 2^4) + (1 * 2^3) + (0 * 2^2) + (1 * 2^1) + (0 * 2^0)`
 
-The number 1120, *in base 3*, means:
+The number 1120, _in base 3_, means:
 
 `(1 * 3^3) + (1 * 3^2) + (2 * 3^1) + (0 * 3^0)`
 
 I think you got the idea!
 
-*Yes. Those three numbers above are exactly the same. Congratulations!*
+_Yes. Those three numbers above are exactly the same. Congratulations!_
 
 [positional-notation]: https://en.wikipedia.org/wiki/Positional_notation

exercises/allergies/description.md

@@ -22,6 +22,6 @@ Now, given just that score of 34, your program should be able to say:
 - Whether Tom is allergic to any one of those allergens listed above.
 - All the allergens Tom is allergic to.
 
-Note: a given score may include allergens **not** listed above (i.e.  allergens that score 256, 512, 1024, etc.).
+Note: a given score may include allergens **not** listed above (i.e. allergens that score 256, 512, 1024, etc.).
 Your program should ignore those components of the score.
 For example, if the allergy score is 257, your program should only report the eggs (1) allergy.

exercises/armstrong-numbers/description.md

@@ -5,9 +5,9 @@ An [Armstrong number][armstrong-number] is a number that is the sum of its own d
 For example:
 
 - 9 is an Armstrong number, because `9 = 9^1 = 9`
-- 10 is *not* an Armstrong number, because `10 != 1^2 + 0^2 = 1`
+- 10 is _not_ an Armstrong number, because `10 != 1^2 + 0^2 = 1`
 - 153 is an Armstrong number, because: `153 = 1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153`
-- 154 is *not* an Armstrong number, because: `154 != 1^3 + 5^3 + 4^3 = 1 + 125 + 64 = 190`
+- 154 is _not_ an Armstrong number, because: `154 != 1^3 + 5^3 + 4^3 = 1 + 125 + 64 = 190`
 
 Write some code to determine whether a number is an Armstrong number.
 

exercises/binary-search/instructions.md

@@ -5,13 +5,13 @@ Your task is to implement a binary search algorithm.
 A binary search algorithm finds an item in a list by repeatedly splitting it in half, only keeping the half which contains the item we're looking for.
 It allows us to quickly narrow down the possible locations of our item until we find it, or until we've eliminated all possible locations.
 
-~~~~exercism/caution
+```exercism/caution
 Binary search only works when a list has been sorted.
-~~~~
+```
 
 The algorithm looks like this:
 
-- Find the middle element of a *sorted* list and compare it with the item we're looking for.
+- Find the middle element of a _sorted_ list and compare it with the item we're looking for.
 - If the middle element is our item, then we're done!
 - If the middle element is greater than our item, we can eliminate that element and all the elements **after** it.
 - If the middle element is less than our item, we can eliminate that element and all the elements **before** it.

exercises/binary/description.md

@@ -20,7 +20,7 @@ A number 23 in base 10 notation can be understood as a linear combination of pow
 - The rightmost digit gets multiplied by 10^0 = 1
 - The next number gets multiplied by 10^1 = 10
 - ...
-- The *n*th number gets multiplied by 10^*(n-1)*.
+- The nth number gets multiplied by 10^_(n-1)_.
 - All these values are summed.
 
 So: `23 => 2*10^1 + 3*10^0 => 2*10 + 3*1 = 23 base 10`

exercises/book-store/description.md

@@ -36,8 +36,8 @@ This would give a total of:
 
 Resulting in:
 
-- 5 × (100% - 25%) * $8 = 5 × $6.00 = $30.00, plus
-- 3 × (100% - 10%) * $8 = 3 × $7.20 = $21.60
+- 5 × (100% - 25%) × $8 = 5 × $6.00 = $30.00, plus
+- 3 × (100% - 10%) × $8 = 3 × $7.20 = $21.60
 
 Which equals $51.60.
 
@@ -53,8 +53,8 @@ This would give a total of:
 
 Resulting in:
 
-- 4 × (100% - 20%) * $8 = 4 × $6.40 = $25.60, plus
-- 4 × (100% - 20%) * $8 = 4 × $6.40 = $25.60
+- 4 × (100% - 20%) × $8 = 4 × $6.40 = $25.60, plus
+- 4 × (100% - 20%) × $8 = 4 × $6.40 = $25.60
 
 Which equals $51.20.
 

exercises/bowling/description.md

@@ -23,9 +23,9 @@ There are three cases for the tabulation of a frame.
 
 Here is a three frame example:
 
-| Frame 1         | Frame 2       | Frame 3                |
-| :-------------: |:-------------:| :---------------------:|
-| X (strike)      | 5/ (spare)    | 9 0 (open frame)       |
+|  Frame 1   |  Frame 2   |     Frame 3      |
+| :--------: | :--------: | :--------------: |
+| X (strike) | 5/ (spare) | 9 0 (open frame) |
 
 Frame 1 is (10 + 5 + 5) = 20
 

exercises/circular-buffer/description.md

@@ -4,39 +4,55 @@ A circular buffer, cyclic buffer or ring buffer is a data structure that uses a
 
 A circular buffer first starts empty and of some predefined length.
 For example, this is a 7-element buffer:
-<!-- prettier-ignore -->
-    [ ][ ][ ][ ][ ][ ][ ]
+
+```text
+[ ][ ][ ][ ][ ][ ][ ]
+```
 
 Assume that a 1 is written into the middle of the buffer (exact starting location does not matter in a circular buffer):
-<!-- prettier-ignore -->
-    [ ][ ][ ][1][ ][ ][ ]
+
+```text
+[ ][ ][ ][1][ ][ ][ ]
+```
 
 Then assume that two more elements are added — 2 & 3 — which get appended after the 1:
-<!-- prettier-ignore -->
-    [ ][ ][ ][1][2][3][ ]
+
+```text
+[ ][ ][ ][1][2][3][ ]
+```
 
 If two elements are then removed from the buffer, the oldest values inside the buffer are removed.
 The two elements removed, in this case, are 1 & 2, leaving the buffer with just a 3:
-<!-- prettier-ignore -->
-    [ ][ ][ ][ ][ ][3][ ]
+
+```text
+[ ][ ][ ][ ][ ][3][ ]
+```
 
 If the buffer has 7 elements then it is completely full:
-<!-- prettier-ignore -->
-    [5][6][7][8][9][3][4]
+
+```text
+[5][6][7][8][9][3][4]
+```
 
 When the buffer is full an error will be raised, alerting the client that further writes are blocked until a slot becomes free.
 
 When the buffer is full, the client can opt to overwrite the oldest data with a forced write.
 In this case, two more elements — A & B — are added and they overwrite the 3 & 4:
-<!-- prettier-ignore -->
-    [5][6][7][8][9][A][B]
+
+```text
+[5][6][7][8][9][A][B]
+```
 
 3 & 4 have been replaced by A & B making 5 now the oldest data in the buffer.
 Finally, if two elements are removed then what would be returned is 5 & 6 yielding the buffer:
-<!-- prettier-ignore -->
-    [ ][ ][7][8][9][A][B]
+
+```text
+[ ][ ][7][8][9][A][B]
+```
 
 Because there is space available, if the client again uses overwrite to store C & D then the space where 5 & 6 were stored previously will be used not the location of 7 & 8.
 7 is still the oldest element and the buffer is once again full.
-<!-- prettier-ignore -->
-    [C][D][7][8][9][A][B]
+
+```text
+[C][D][7][8][9][A][B]
+```

exercises/counter/description.md

@@ -5,7 +5,8 @@
 Please see the discussion in [https://github.com/exercism/problem-specifications/issues/80](https://github.com/exercism/problem-specifications/issues/80)
 for more context.
 
---------
+---
+
 Design a test suite for a line/letter/character counter tool.
 
 This is a special exercise. Instead of creating code that works with

exercises/dot-dsl/description.md

@@ -1,7 +1,7 @@
 # Description
 
 A [Domain Specific Language (DSL)][dsl] is a small language optimized for a specific domain.
-Since a DSL is targeted, it can greatly impact productivity/understanding by allowing the writer to declare *what* they want rather than *how*.
+Since a DSL is targeted, it can greatly impact productivity/understanding by allowing the writer to declare _what_ they want rather than _how_.
 
 One problem area where they are applied are complex customizations/configurations.
 

exercises/etl/instructions.md

@@ -22,6 +22,6 @@ This needs to be changed to store each individual letter with its score in a one
 
 As part of this change, the team has also decided to change the letters to be lower-case rather than upper-case.
 
-~~~~exercism/note
+```exercism/note
 If you want to look at how the data was previously structured and how it needs to change, take a look at the examples in the test suite.
-~~~~
+```

exercises/gigasecond/introduction.md

@@ -13,12 +13,12 @@ Then we can use metric system prefixes for writing large numbers of seconds in m
 - Perhaps you and your family would travel to somewhere exotic for two megaseconds (that's two million seconds).
 - And if you and your spouse were married for _a thousand million_ seconds, you would celebrate your one gigasecond anniversary.
 
-~~~~exercism/note
+```exercism/note
 If we ever colonize Mars or some other planet, measuring time is going to get even messier.
 If someone says "year" do they mean a year on Earth or a year on Mars?
 
 The idea for this exercise came from the science fiction novel ["A Deepness in the Sky"][vinge-novel] by author Vernor Vinge.
 In it the author uses the metric system as the basis for time measurements.
 
 [vinge-novel]: https://www.tor.com/2017/08/03/science-fiction-with-something-for-everyone-a-deepness-in-the-sky-by-vernor-vinge/
-~~~~
+```

exercises/isogram/description.md

@@ -11,4 +11,4 @@ Examples of isograms:
 - downstream
 - six-year-old
 
-The word *isograms*, however, is not an isogram, because the s repeats.
+The word _isograms_, however, is not an isogram, because the s repeats.

exercises/linked-list/instructions.md

@@ -13,7 +13,7 @@ Sometimes a station gets closed down, and in that case the station needs to be r
 
 The size of a route is measured not by how far the train travels, but by how many stations it stops at.
 
-~~~~exercism/note
+```exercism/note
 The linked list is a fundamental data structure in computer science, often used in the implementation of other data structures.
 As the name suggests, it is a list of nodes that are linked together.
 It is a list of "nodes", where each node links to its neighbor or neighbors.
@@ -23,4 +23,4 @@ In a **doubly linked list** each node links to both the node that comes before,
 If you want to dig deeper into linked lists, check out [this article][intro-linked-list] that explains it using nice drawings.
 
 [intro-linked-list]: https://medium.com/basecs/whats-a-linked-list-anyway-part-1-d8b7e6508b9d
-~~~~
+```

exercises/list-ops/description.md

@@ -7,13 +7,13 @@ Implement a series of basic list operations, without using existing functions.
 
 The precise number and names of the operations to be implemented will be track dependent to avoid conflicts with existing names, but the general operations you will implement include:
 
-- `append` (*given two lists, add all items in the second list to the end of the first list*);
-- `concatenate` (*given a series of lists, combine all items in all lists into one flattened list*);
-- `filter` (*given a predicate and a list, return the list of all items for which `predicate(item)` is True*);
-- `length` (*given a list, return the total number of items within it*);
-- `map` (*given a function and a list, return the list of the results of applying `function(item)` on all items*);
-- `foldl` (*given a function, a list, and initial accumulator, fold (reduce) each item into the accumulator from the left*);
-- `foldr` (*given a function, a list, and an initial accumulator, fold (reduce) each item into the accumulator from the right*);
-- `reverse` (*given a list, return a list with all the original items, but in reversed order*).
+- `append` (_given two lists, add all items in the second list to the end of the first list_);
+- `concatenate` (_given a series of lists, combine all items in all lists into one flattened list_);
+- `filter` (_given a predicate and a list, return the list of all items for which `predicate(item)` is True_);
+- `length` (_given a list, return the total number of items within it_);
+- `map` (_given a function and a list, return the list of the results of applying `function(item)` on all items_);
+- `foldl` (_given a function, a list, and initial accumulator, fold (reduce) each item into the accumulator from the left_);
+- `foldr` (_given a function, a list, and an initial accumulator, fold (reduce) each item into the accumulator from the right_);
+- `reverse` (_given a list, return a list with all the original items, but in reversed order_).
 
 Note, the ordering in which arguments are passed to the fold functions (`foldl`, `foldr`) is significant.

exercises/octal/description.md

@@ -21,7 +21,7 @@ as a linear combination of powers of 10:
 - The rightmost digit gets multiplied by 10^0 = 1
 - The next number gets multiplied by 10^1 = 10
 - ...
-- The *n*th number gets multiplied by 10^*(n-1)*.
+- The nth number gets multiplied by 10^_(n-1)_.
 - All these values are summed.
 
 So:

exercises/pangram/introduction.md

@@ -7,10 +7,10 @@ To give a comprehensive sense of the font, the random sentences should use **all
 They're running a competition to get suggestions for sentences that they can use.
 You're in charge of checking the submissions to see if they are valid.
 
-~~~~exercism/note
+```exercism/note
 Pangram comes from Greek, παν γράμμα, pan gramma, which means "every letter".
 
 The best known English pangram is:
 
 > The quick brown fox jumps over the lazy dog.
-~~~~
+```

exercises/phone-number/description.md

@@ -5,8 +5,8 @@ Clean up user-entered phone numbers so that they can be sent SMS messages.
 The **North American Numbering Plan (NANP)** is a telephone numbering system used by many countries in North America like the United States, Canada or Bermuda.
 All NANP-countries share the same international country code: `1`.
 
-NANP numbers are ten-digit numbers consisting of a three-digit Numbering Plan Area code, commonly known as *area code*, followed by a seven-digit local number.
-The first three digits of the local number represent the *exchange code*, followed by the unique four-digit number which is the *subscriber number*.
+NANP numbers are ten-digit numbers consisting of a three-digit Numbering Plan Area code, commonly known as _area code_, followed by a seven-digit local number.
+The first three digits of the local number represent the _exchange code_, followed by the unique four-digit number which is the _subscriber number_.
 
 The format is usually represented as