Skip to content

Instantly share code, notes, and snippets.

View gallais's full-sized avatar

G. Allais gallais

View GitHub Profile
@gallais
gallais / EquationalReasoning.v
Last active January 13, 2021 14:18
Equational Reasoning in Coq, using tactics inside terms!
Require Import Coq.Setoids.Setoid.
Require Import Arith.
Notation "`Begin p" := p (at level 20, right associativity).
Notation "a =] p ] pr" := (@eq_trans _ a _ _ p pr) (at level 30, right associativity).
Notation "a =[ p [ pr" := (@eq_trans _ a _ _ (eq_sym p) pr) (at level 30, right associativity).
Notation "a `End" := (@eq_refl _ a) (at level 10).
Definition times2 : forall n, n + n = 2 * n := fun n =>
`Begin
@gallais
gallais / Smaller.agda
Created August 2, 2020 14:52
Returning a smaller sized list
open import Agda.Builtin.Size
open import Data.Maybe.Base
data List {n} (T : Set n) (i : Size) : Set n where
[] : List T i
_∷_ : ∀ {j : Size< i} → T → List T j → List T i
data Smaller {n} (T : Size → Set n) (i : Size) : Set n where
[_] : {j : Size< i} → T j → Smaller T i
{-# OPTIONS --safe --without-K #-}
module SyntaxDesc (I : Set) where
open import Agda.Primitive using () renaming (Set to Type)
open import Data.Nat.Base
open import Data.Fin.Base
open import Data.List.Base using (List; []; _∷_; _++_)
data Desc : Type₀ where
@gallais
gallais / PalAcc.v
Created May 22, 2020 12:02
Palindrome via an accumulator-based definition.
Require Import List.
Inductive PalAcc {A : Type} (acc : list A) : list A -> Type
:= Even : PalAcc acc acc
| Odd : forall x, PalAcc acc (x :: acc)
| Step : forall x xs, PalAcc (x :: acc) xs -> PalAcc acc (x :: xs)
.
Definition Pal {A : Type} (xs : list A) : Type := PalAcc nil xs.
@gallais
gallais / get.v
Last active March 4, 2020 18:44
Terminating map via commuting conversions
Inductive Tree (A : Set) : Set :=
| Leaf : A -> Tree A
| Node : bool -> Tree A * Tree A -> Tree A.
Definition subTree {A : Set} (b : bool) (lr : Tree A * Tree A) : Tree A :=
match (b, lr) with
| (true, (a, b)) => a
| (false, (a, b)) => b
end.
@gallais
gallais / Negative.idr
Created March 2, 2020 11:56
Using the lack of strict positivity to run an infinite computation
data EventT : (event : Type) -> (m : Type -> Type) -> (a : Type) -> Type where
MkEventTCont : (event -> m (EventT event m a)) -> EventT event m a
MkEventTTerm : m a -> EventT event m a
MkEventTEmpty : EventT event m a
data LAM : (x : Type) -> Type where
App : x -> x -> LAM x
Lam : (x -> x) -> LAM x
LC : Type
@gallais
gallais / search.agda
Created December 17, 2019 20:12
example of search
open import Agda.Builtin.Equality
open import Agda.Builtin.Nat hiding (_+_; _<_)
open import Data.Nat
open import Data.Nat.Properties
open import Relation.Binary
-- C-c C-z RET _*_ _≡_ RET
@gallais
gallais / Rose.agda
Created June 4, 2019 10:41
Use case for ∷-dec
open import Data.List using (List); open List
open import Data.List.Properties
open import Data.Product
open import Relation.Nullary
open import Relation.Nullary.Decidable
open import Relation.Nullary.Product
open import Relation.Binary
open import Relation.Binary.PropositionalEquality
private variable A : Set
@gallais
gallais / linear.agda
Last active March 26, 2019 21:57
Raw linear terms
open import Data.Nat.Base
open import Data.Vec
open import Data.Bool.Base using (Bool; false; true)
open import Data.Product
variable
m n : ℕ
b : Bool
Γ Δ Ξ T I O : Vec Bool n
open import Size
open import Codata.Thunk
data BinaryTreePath (i : Size) : Set where
here : BinaryTreePath i
branchL : Thunk BinaryTreePath i → BinaryTreePath i
branchR : Thunk BinaryTreePath i → BinaryTreePath i
zero : ∀ {i} → BinaryTreePath i
zero = branchL λ where .force → zero