doug/Doug/Basic.lean
qwjyh 8d6fc4d214
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rewrite with custom Monad (without monad transformer)
2024-10-21 22:27:06 +09:00

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def hello := "world"
structure Config where
useASCII : Bool := false
currentPrefix : String := ""
def ConfigIO (α : Type) : Type :=
Config → IO α
instance : Monad ConfigIO where
pure x := fun _ => pure x
bind result next := fun cfg => do
let v ← result cfg
next v cfg
#print ConfigIO
#check (Monad ConfigIO)
#check Monad.mk
def ConfigIO.run (action : ConfigIO α) (cfg : Config) : IO α :=
action cfg
def currentConfig : ConfigIO Config :=
fun cfg => pure cfg
def locally (change : Config → Config) (action : ConfigIO α) : ConfigIO α :=
fun cfg => action (change cfg)
def runIO (action : IO α) : ConfigIO α :=
fun _ => action
def usage : String :=
"Usage: doug [--ascii]
Options:
\t--ascii\tUse ASCII characters to display the directry structure"
def configFromArgs : List String → Option Config
| [] => some {}
| ["--ascii"] => some {useASCII := true}
| _ => none
inductive Entry where
| file : String → Entry
| dir : String → Entry
def toEntry (path : System.FilePath) : IO (Option Entry) := do
match path.components.getLast? with
| none => pure (some (.dir ""))
| some "." | some ".." => pure none
| some name =>
pure (some (if (← path.isDir) then .dir name else .file name))
def Config.preFile (cfg : Config) :=
if cfg.useASCII then "|--" else "├──"
def Config.preDir (cfg : Config) :=
if cfg.useASCII then "| " else "│ "
def Config.fileName (cfg : Config) (file : String) : String :=
s!"{cfg.currentPrefix}{cfg.preFile} {file}"
def Config.dirName (cfg : Config) (dir : String) : String :=
s!"{cfg.currentPrefix}{cfg.preDir} {dir}/"
/--
Modify `cfg` on entering a directory.
-/
def Config.inDirectory (cfg : Config) : Config :=
{cfg with currentPrefix := cfg.preDir ++ " " ++ cfg.currentPrefix}
def showFileName (file : String) : ConfigIO Unit := do
runIO (IO.println ((← currentConfig).fileName file))
def showDirName (dir : String) : ConfigIO Unit := do
runIO (IO.println ((← currentConfig).dirName dir))
def doList [Applicative f] : List α → (α → f Unit) → f Unit
| [], _ => pure ()
| x :: xs, action =>
action x *>
doList xs action
partial def dirTree (path : System.FilePath) : ConfigIO Unit := do
match ← runIO (toEntry path) with
| none => pure ()
| some (.file name) => showFileName name
| some (.dir name) =>
showDirName name
let contents ← runIO path.readDir
locally (·.inDirectory)
(doList contents.toList fun d =>
dirTree d.path)
def main (args : List String) : IO UInt32 := do
match configFromArgs args with
| some config =>
(dirTree (← IO.currentDir)).run config
pure 0
| none =>
IO.eprintln s!"Didn't understand argument(s) {" ".intercalate args}\n"
IO.eprintln usage
pure 1