77 lines
2.9 KiB
Text
77 lines
2.9 KiB
Text
/-
|
||
Copyright (c) 2016 Microsoft Corporation. All rights reserved.
|
||
Released under Apache 2.0 license as described in the file LICENSE.
|
||
Authors: Jeremy Avigad, Leonardo de Moura
|
||
|
||
Monad Combinators, as in Haskell's Control.Monad.
|
||
-/
|
||
prelude
|
||
import init.control.monad init.control.alternative init.data.list.basic init.coe
|
||
universes u v w
|
||
|
||
@[specialize]
|
||
def Nat.mrepeat {m} [Monad m] (n : Nat) (f : Nat → m Unit) : m Unit :=
|
||
n.repeat (λ i a, a *> f i) (pure ())
|
||
|
||
@[specialize]
|
||
def List.mmap {m : Type u → Type v} [Monad m] {α : Type w} {β : Type u} (f : α → m β) : List α → m (List β)
|
||
| [] := pure []
|
||
| (h :: t) := do h' ← f h, t' ← List.mmap t, pure (h' :: t')
|
||
|
||
@[specialize]
|
||
def List.mmap' {m : Type u → Type v} [Monad m] {α : Type w} {β : Type u} (f : α → m β) : List α → m Punit
|
||
| [] := pure ⟨⟩
|
||
| (h :: t) := f h *> List.mmap' t
|
||
|
||
@[specialize]
|
||
def List.mfor {m : Type u → Type v} [Monad m] {α : Type w} {β : Type u} (f : α → m β) : List α → m Punit :=
|
||
List.mmap' f
|
||
|
||
def mjoin {m : Type u → Type u} [Monad m] {α : Type u} (a : m (m α)) : m α :=
|
||
bind a id
|
||
|
||
@[specialize]
|
||
def List.mfilter {m : Type → Type v} [Monad m] {α : Type} (f : α → m Bool) : List α → m (List α)
|
||
| [] := pure []
|
||
| (h :: t) := do b ← f h, t' ← List.mfilter t, cond b (pure (h :: t')) (pure t')
|
||
|
||
@[specialize]
|
||
def List.mfoldl {m : Type u → Type v} [Monad m] {s : Type u} {α : Type w} : (s → α → m s) → s → List α → m s
|
||
| f s [] := pure s
|
||
| f s (h :: r) := do
|
||
s' ← f s h,
|
||
List.mfoldl f s' r
|
||
|
||
@[specialize]
|
||
def List.mfoldr {m : Type u → Type v} [Monad m] {s : Type u} {α : Type w} : (α → s → m s) → s → List α → m s
|
||
| f s [] := pure s
|
||
| f s (h :: r) := do
|
||
s' ← List.mfoldr f s r,
|
||
f h s'
|
||
|
||
@[specialize]
|
||
def List.mfirst {m : Type u → Type v} [Monad m] [Alternative m] {α : Type w} {β : Type u} (f : α → m β) : List α → m β
|
||
| [] := failure
|
||
| (a::as) := f a <|> List.mfirst as
|
||
|
||
@[specialize]
|
||
def List.mexists {m : Type → Type u} [Monad m] {α : Type v} (f : α → m Bool) : List α → m Bool
|
||
| [] := pure false
|
||
| (a::as) := do b ← f a, if b then pure true else List.mexists as
|
||
|
||
@[specialize]
|
||
def List.mforall {m : Type → Type u} [Monad m] {α : Type v} (f : α → m Bool) : List α → m Bool
|
||
| [] := pure true
|
||
| (a::as) := do b ← f a, if b then List.mforall as else pure false
|
||
|
||
@[macroInline] def when {m : Type → Type u} [Monad m] (c : Prop) [h : Decidable c] (t : m Unit) : m Unit :=
|
||
if c then t else pure ()
|
||
|
||
@[macroInline] def unless {m : Type → Type u} [Monad m] (c : Prop) [h : Decidable c] (e : m Unit) : m Unit :=
|
||
if c then pure () else e
|
||
|
||
@[macroInline] def mcond {m : Type → Type u} [Monad m] {α : Type} (mbool : m Bool) (tm fm : m α) : m α :=
|
||
do b ← mbool, cond b tm fm
|
||
|
||
@[macroInline] def mwhen {m : Type → Type u} [Monad m] (c : m Bool) (t : m Unit) : m Unit :=
|
||
mcond c t (pure ())
|