base.System.REPL.idr Maven / Gradle / Ivy
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module System.REPL
import System.File
%default covering
||| A basic read-eval-print loop, maintaining a state
|||
||| @ state the input state
||| @ prompt the prompt to show
||| @ onInput the function to run on reading input, returning a String to
||| output and a new state. Returns Nothing if the repl should exit
export
replWith : HasIO io =>
(state : a) -> (prompt : String) ->
(onInput : a -> String -> Maybe (String, a)) -> io ()
replWith acc prompt fn
= do eof <- fEOF stdin
if eof
then pure ()
else do putStr prompt
fflush stdout
x <- getLine
case fn acc x of
Just (out, acc') =>
do putStr out
replWith acc' prompt fn
Nothing => pure ()
||| A basic read-eval-print loop
|||
||| @ prompt the prompt to show
||| @ onInput the function to run on reading input, returning a String to
||| output
export
repl : HasIO io =>
(prompt : String) -> (onInput : String -> String) -> io ()
repl prompt fn
= replWith () prompt (\x, s => Just (fn s, ()))