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Getting Started

Installation

pip install ffmt

cargo install ffmt

git clone https://github.com/sbryngelson/ffmt
cd ffmt
cargo install --path .

Usage

ffmt src/                        # format in-place
ffmt --check src/                # CI mode (exit 1 if changes needed)
ffmt --diff src/                 # show colored diff
ffmt -j 8 src/                   # parallel
cat file.fpp | ffmt -            # stdin/stdout
ffmt --range 10:50 file.fpp      # format only lines 10-50
ffmt --no-cache src/             # ignore file modification cache

Quick start

ffmt works out of the box with no configuration. Just run it on your source directory:

ffmt src/

To check formatting without modifying files (useful for CI):

ffmt --check src/

Configuration

Create ffmt.toml in your project root, or add [tool.ffmt] to pyproject.toml. See Configuration for all options.

Most projects need no config file -- the defaults are designed for modern Fortran with Fypp preprocessing.

Format suppression

Disable formatting for specific code regions:

! ffmt off
x    =    1       ! preserved exactly as written
y=2;z=3
! ffmt on
w = 4              ! formatted normally

What gets preserved

ffmt never modifies:

  • Code between ! ffmt off and ! ffmt on markers
  • String literals and inline expressions (${...}$, @{...}@)
  • Doxygen comment structure (!<, !>, !! associations)
  • Continuation line structure across #ifdef/#:if preprocessor blocks
  • #ifdef/#endif blocks (no indentation change)
  • Fypp/Python code inside $: and @: macro invocations
  • !$acc and !$omp directive lines