srcloc for bangs

Main.hs

{-# LANGUAGE BangPatterns #-}

module Main where

import Language.Haskell.Exts
import Language.Haskell.Exts.Syntax
import Data.Generics.Uniplate.DataOnly

main :: IO ()
main = do
  ParseOk s <- parseFile "/Users/rem/exp/app/Main.hs"
  let !locs = [ l | PBangPat l p <- universeBi s] :: [SrcSpanInfo]
  print locs

This programs prints out a list of the location of the bang patterns in a file. When ran on itself, it prints out [SrcSpanInfo {srcInfoSpan = SrcSpan "/Users/rem/exp/app/Main.hs" 12 7 12 12, srcInfoPoints = [SrcSpan "/Users/rem/exp/app/Main.hs" 12 7 12 8]}], which means there's a bang around the pattern on line 12 from column 7 to column 12 (loc). Then to find out the exact location of the bang itself in the source just take the first column number and -1.

Nvm you don't need to -1, the first column is exactly where the bang is.