Configuration

Configuration options may be specified in either a fourmolu.yaml file or via command-line options. Fourmolu looks for a fourmolu.yaml file in all parents of the current directory, followed by the XDG config directory.

A configuration file with the default values filled in can be generated with:

$ fourmolu --print-defaults > fourmolu.yaml

For example, the indentation option may be specified in fourmolu.yaml as:

indentation: 2

or on the command line as --indentation 2 or --indentation=2.

Every option also has a setting that matches Ormolu's formatting.

Available options

Option name	Description
`indentation`	Number of spaces per indentation step
`column-limit`	Max line length for automatic line breaking
`function-arrows`	Styling of arrows in type signatures
`comma-style`	How to place commas in multi-line lists, records, etc.
`import-export-style`	Styling of import/export lists
`indent-wheres`	Whether to full-indent or half-indent 'where' bindings past the preceding body
`record-brace-space`	Whether to leave a space before an opening record brace
`newlines-between-decls`	Number of spaces between top-level declarations
`haddock-style`	How to print Haddock comments
`haddock-style-module`	How to print module docstring
`let-style`	Styling of let blocks
`in-style`	How to align the 'in' keyword with respect to the 'let' keyword
`single-constraint-parens`	Whether to put parentheses around a single constraint
`single-deriving-parens`	Whether to put parentheses around a single deriving class
`unicode`	Output Unicode syntax
`respectful`	Give the programmer more choice on where to insert blank lines
`fixities`	Fixity information for operators
`reexports`	Module reexports Fourmolu should know about
`import-grouping`	Rules for grouping import declarations
`local-modules`	Modules defined by the current Cabal package for import grouping
`sort-constraints`	Whether to sort constraints
`sort-derived-classes`	Whether to sort derived classes
`sort-deriving-clauses`	Whether to sort deriving clauses