A formatter for the Miranda functional programming language in Visual Studio
Code. It applies a set of conservative style transformations: it cleans up
and normalizes your code without risking the language's layout-sensitive
semantics (the offside rule).
What it does
Aligns guarded equations. Each alternative = rhs, if cond is moved to the
column of the first =, and the if / otherwise guards are aligned into a
single column. This is the core use case and the most Miranda-specific feature:
Before:
gcd a b = gcd (a-b) b, if a>b
= gcd a (b-a), if a<b
= a, if a=b
After:
gcd a b = gcd (a-b) b, if a>b
= gcd a (b-a), if a<b
= a, if a=b
One space after each comma (outside strings and comments).
Normalizes :: spacing in type signatures (without touching ::= in
algebraic data types).
Converts tabs to spaces, trims trailing whitespace, and collapses
consecutive blank lines.
Conservative by design (offside rule)
Miranda uses layout (indentation) to delimit blocks such as where clauses,
equation alternatives, and multi-line expressions. Reindenting blindly can change
a program's meaning, so the formatter:
Never reindents where blocks or multi-line expressions.
Only changes the indentation of continuation lines that start with = (the
alternatives of a guarded equation), which is safe and matches the language's
canonical style.
Never touches the contents of strings, character literals, or comments.
Formatting is idempotent: running it twice produces the same result.
Usage
Open a Miranda file (.m, .mira, or .mir), or set the document language to
Miranda.
Run Format Document (Shift+Alt+F) or format a selection.
Optionally enable Format On Save.
Note: VS Code also associates .m with Objective-C. If your file uses .m,
pick the Miranda language mode in the status bar.
Settings
Setting
Default
Description
mirandaFormatter.alignGuards
true
Align alternatives and guards.
mirandaFormatter.normalizeCommentSpacing
true
Space after ||.
mirandaFormatter.spaceAfterComma
true
Space after commas.
mirandaFormatter.normalizeTypeSignatureSpacing
true
Spacing around ::.
mirandaFormatter.convertTabsToSpaces
true
Tabs to spaces.
mirandaFormatter.indentSize
2
Spaces per tab.
mirandaFormatter.trimTrailingWhitespace
true
Trim end of line.
mirandaFormatter.maxConsecutiveBlankLines
1
Max blank lines in a row.
Development
npm install
npm run compile
npm test
The formatting logic lives in src/core/ and does not depend on the VS Code API,
so it can be unit-tested in isolation. src/extension.ts only wires that logic to
the editor's formatting providers.
