58 lines
1.9 KiB
Text
58 lines
1.9 KiB
Text
/-
|
|
Copyright (c) 2020 Microsoft Corporation. All rights reserved.
|
|
Released under Apache 2.0 license as described in the file LICENSE.
|
|
Authors: Leonardo de Moura
|
|
-/
|
|
prelude
|
|
import Init.Meta
|
|
|
|
namespace Std
|
|
-- We put `Range` in `Init` because we want the notation `[i:j]` without importing `Std`
|
|
-- We don't put `Range` in the top-level namespace to avoid collisions with user defined types
|
|
structure Range where
|
|
start : Nat := 0
|
|
stop : Nat
|
|
step : Nat := 1
|
|
|
|
namespace Range
|
|
universe u v
|
|
|
|
@[inline] protected def forIn {β : Type u} {m : Type u → Type v} [Monad m] (range : Range) (init : β) (f : Nat → β → m (ForInStep β)) : m β :=
|
|
let rec @[specialize] loop (i : Nat) (j : Nat) (b : β) : m β := do
|
|
if j ≥ range.stop then
|
|
pure b
|
|
else match i with
|
|
| 0 => pure b
|
|
| i+1 => match (← f j b) with
|
|
| ForInStep.done b => pure b
|
|
| ForInStep.yield b => loop i (j + range.step) b
|
|
loop range.stop range.start init
|
|
|
|
instance : ForIn m Range Nat where
|
|
forIn := Range.forIn
|
|
|
|
@[inline] protected def forM {m : Type u → Type v} [Monad m] (range : Range) (f : Nat → m PUnit) : m PUnit :=
|
|
let rec @[specialize] loop (i : Nat) (j : Nat) : m PUnit := do
|
|
if j ≥ range.stop then
|
|
pure ⟨⟩
|
|
else match i with
|
|
| 0 => pure ⟨⟩
|
|
| i+1 => f j; loop i (j + range.step)
|
|
loop range.stop range.start
|
|
|
|
instance : ForM m Range Nat where
|
|
forM := Range.forM
|
|
|
|
syntax:max "[" ":" term "]" : term
|
|
syntax:max "[" term ":" term "]" : term
|
|
syntax:max "[" ":" term ":" term "]" : term
|
|
syntax:max "[" term ":" term ":" term "]" : term
|
|
|
|
macro_rules
|
|
| `([ : $stop]) => `({ stop := $stop : Range })
|
|
| `([ $start : $stop ]) => `({ start := $start, stop := $stop : Range })
|
|
| `([ $start : $stop : $step ]) => `({ start := $start, stop := $stop, step := $step : Range })
|
|
| `([ : $stop : $step ]) => `({ stop := $stop, step := $step : Range })
|
|
|
|
end Range
|
|
end Std
|