Created
July 17, 2024 22:02
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This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode charactersOriginal file line number Diff line number Diff line change @@ -0,0 +1,54 @@ partial def grep (stream : IO.FS.Stream) (expected : String) : IO Unit := do let line ← stream.getLine if line.isEmpty then pure () else let words := line.splitOn " " if words.contains expected then IO.print line grep stream expected def fileStream (filename : System.FilePath) : IO (Option IO.FS.Stream) := do let fileExists ← filename.pathExists if not fileExists then let stderr ← IO.getStderr stderr.putStrLn s!"File not found: {filename}" pure none else let handle ← IO.FS.Handle.mk filename IO.FS.Mode.read pure (some (IO.FS.Stream.ofHandle handle)) def processFiles (expected : String) (files : List String) : IO UInt32 := do match files with | [] => pure 0 | filename :: rest => let streamOpt ← fileStream filename match streamOpt with | none => let code ← processFiles expected rest pure (code+1) | some stream => grep stream expected processFiles expected rest def process (expected : String) (files : List String) : IO UInt32 := do match files with | [] => let stdin ← IO.getStdin grep stdin expected pure 0 | _ => processFiles expected files def printUsage : IO UInt32 := do let stdout ← IO.getStdout stdout.putStrLn "grep [--help] expected_word [files]" pure (1) def main (args : List String) : IO UInt32 := match args with | [] => printUsage | [x] => process x [] | x :: xs => process x xs