Parser in Curry (fl-parser 3.0.0)

parse.curry

-- cypm add fl-parser
-- ported from: https://www-ps.informatik.uni-kiel.de/~cpm/DOC/fl-parser-3.0.0/Parser_curry.html
import Parser

num = Parser.some digit l >>> numeric_value l
  where l free
        numeric_value ds = foldl1 (\acc x -> 10*acc+x) (map (\c -> ord c-ord '0') ds)

expr =   term m Parser.<*> terminal '+' Parser.<*> expr n >>> m+n
    <||> term m Parser.<*> terminal '-' Parser.<*> expr n >>> m-n
    <||> term
  where m,n free

term =   factor m Parser.<*> terminal '*' Parser.<*> term n >>> m*n
    <||> factor m Parser.<*> terminal '/' Parser.<*> term n >>> div m n
    <||> num
  where m,n free

factor = terminal '(' Parser.<*> expr e Parser.<*> terminal ')' >>> e
    <||> num
  where e free

digit = satisfy isDigit

-- expr n "(10+5*2)/4" =:= [] where n free