quox/examples/io.quox
2023-11-05 15:48:01 +01:00

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load "misc.quox"
namespace io {
def0 IORes : ★ → ★ = λ A ⇒ A × IOState
def0 IO : ★ → ★ = λ A ⇒ IOState → IORes A
def pure : 0.(A : ★) → A → IO A = λ A x s ⇒ (x, s)
def bind : 0.(A B : ★) → IO A → (A → IO B) → IO B =
λ A B m k s0 ⇒
case m s0 return IORes B of { (x, s1) ⇒ k x s1 }
def seq : 0.(B : ★) → IO True → IO B → IO B =
λ B x y ⇒ bind True B x (λ u ⇒ case u return IO B of { 'true ⇒ y })
def seq' : IO True → IO True → IO True = seq True
#[compile-scheme "(lambda (str) (builtin-io (display str) 'true))"]
postulate print : String → IO True
def newline = print "\n"
def println : String → IO True =
λ str ⇒ seq' (print str) newline
#[compile-scheme "(builtin-io (get-line (current-input-port)))"]
postulate readln : IO String
}