monadt_with_IO/Main.lean

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2024-06-05 15:49:21 +09:00
import «MonadtSample»
def ret1 : Except String Nat := .ok 10
def ret2 : Except String Nat := .error "message"
def rets : List (Except String Nat) := [.ok 1, .ok 10, .error "problem 1", .error "problem 2", .ok 100000]
def liftIO (t : ExceptT String Id α) : IO α := do
match t with
| .ok r => EStateM.Result.ok r
| .error s => EStateM.Result.error s
instance : MonadLift (ExceptT String Id) IO where
monadLift := liftIO
def main : IO Unit := do
let fmt := Std.Format.nest 5 <| ".aa gjeoi".toFormat.append ((Std.Format.align true).append ("a".toFormat.append (Std.Format.line.append "b".toFormat)))
IO.println fmt
-- let ret ← ret2
-- IO.println s!"ret: {ret}"
-- let ret ← ret1
-- IO.println s!"ret: {ret}"
try
let ret ← ret1
IO.println s!"ret1: {ret}"
for val in rets do
IO.println s!"ret: {val}"
catch e =>
IO.eprintln s!"Error: {e}"
#eval main
#print main
#eval (1.2).mul 100 |>.round |>.div 100 |>.toString |>.toFormat |>.tag 10
#print Task
def hoge := main.asTask
#check -42.0
#eval 10. * 10^3
#check 10^3
#eval (10.8).toUInt64
#check Float.ofScientific
#eval Float.ofScientific 323 true 1
namespace Float
def sprintf_1 (x : Float) (a : Nat) : String :=
let sign : Bool := x > 0
let up := (if sign then x.toUInt64 else (-x).toUInt64) |>.toNat
let down := (x - up.toFloat) * (10^a).toFloat |>.round |>.toUInt64 |>.toNat
let sign_sign := if sign then "" else "-"
s!"{sign_sign}{up}.{down}"
end Float
#eval (3.14).sprintf_1 0
#eval (3.14).sprintf_1 1
#eval (3.14).sprintf_1 2