prog.levy

return ( 2 + 2 ) ; 
return ( 2 * 3 ) ;
return ( 2 - 4 ) ;

if 5 < 3 then return 1 else return 5 ;
if 2 = 2 then return 1 else return 5 ; 

fun n : int => return ( n + 3 ) ;
fun n : int => if n < 0 then return ( 0 - n ) else return n ;

rec f : int -> F int is fun n : int =>
  if n = 0 then
    return 1
  else
    ( do m <- ( ( force f ) $ ( n - 1 ) ) in return ( n * m ) ) ;

return 42 ;

let_ x = thunk ( if 3 < 5 then return 1 else return 2 ) ;

force ( thunk ( if 3 < 5 then return 1 else return 2 ) ) ;

let x = 3 + 5 in return ( x * x ) ;

do x <- return ( 3 + 5 ) in return ( x * x ) ; 

let_ a = 5 ;
let_ b = 10 + a ;
let_ c = thunk ( return b ) ;

let_ fact = thunk ( rec f : int -> F int is 
  fun k : int =>
    if k = 0 
      then return 1
      else ( 
        do m <- ( ( force f ) $ ( k - 1 ) ) in 
        return ( k * m ) 
      ) 
  ) ; 

( ( force fact ) $ 7 ) ;

force c