97 lines
3.1 KiB
Plaintext
97 lines
3.1 KiB
Plaintext
module Util where
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open import Agda.Builtin.Bool
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open import Agda.Builtin.Char
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open import Agda.Builtin.Equality
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open import Agda.Builtin.List
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open import Agda.Builtin.Maybe
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open import Agda.Builtin.Nat
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open import Agda.Builtin.String
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-- given some default value and a Maybe, definitely return one of them
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default : {V : Set} → V → Maybe V → V
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default n nothing = n
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default n (just m) = m
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-- return the same thing, for functions that need a noop fn
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ident : {V : Set} → V → V
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ident x = x
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-- transform each element of a list
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map : {A B : Set} → (A → B) → List A → List B
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map f [] = []
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map f (x ∷ []) = (f x) ∷ []
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map f (x ∷ xs) = (f x) ∷ (map f xs)
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-- combine two lists
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zip : {V : Set} → List V → List V → List V
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zip [] [] = []
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zip xs [] = xs
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zip [] ys = ys
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zip (x ∷ xs) (y ∷ ys) = x ∷ y ∷ (zip xs ys)
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-- get the length of a list
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len : {A : Set} → List A → Nat
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len [] = 0
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len (x ∷ xs) = suc (len xs)
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-- keep items that pass the predicate
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filter : {A : Set} → (A → Bool) → List A → List A
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filter f [] = []
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filter f (x ∷ xs) with f x
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... | true = x ∷ filter f xs
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... | false = filter f xs
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-- remove nothings from a list of maybes
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filterNothing : {A : Set} → List (Maybe A) → List A
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filterNothing [] = []
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filterNothing (nothing ∷ xs) = filterNothing xs
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filterNothing (just x ∷ xs) = x ∷ filterNothing xs
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-- take the item at the given index
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takeIndex : {A : Set} → A → List A → Nat → A
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takeIndex d [] 0 = d
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takeIndex d [] (suc x) = d
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takeIndex d (x ∷ xs) 0 = x
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takeIndex d (x ∷ xs) (suc n) = takeIndex d xs n
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-- find the index of a number
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findIndex : Nat → Nat → List Nat → Maybe Nat
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findIndex n t [] = nothing
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findIndex n t (x ∷ xs) with (t == x)
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... | true = just n
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... | false = findIndex (suc n) t xs
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-- find the index of a character
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findCharIndex : Nat → Char → List Char → Maybe Nat
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findCharIndex n t [] = nothing
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findCharIndex n t (x ∷ xs) with primCharEquality t x
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... | true = just n
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... | false = findCharIndex (suc n) t xs
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-- generic find if I was smarter
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-- findAny : { A : Set } → Nat → A → List A → Nat
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-- findAny n t [] = n
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-- findAny n t (x ∷ xs) with (t ≡ x)
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-- ... | refl = n
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-- ... | _ = findAny (suc n) t xs
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-- append all of the items in a list
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showList : {V : Set} → (V → String) → List V → String
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showList f [] = ""
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showList f (x ∷ []) = f x
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showList f (x ∷ xs) = primStringAppend (f x) (primStringAppend ", " (showList f xs))
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-- maybe to definitely a string
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showMaybe : {V : Set} → (V → String) → Maybe V → String
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showMaybe f nothing = "nothing"
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showMaybe f (just v) = f v
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split : List Char → List Char → List (List Char)
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split = go [] []
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where
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go : List Char → List (List Char) → List Char → List Char → List (List Char)
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go acc acl delims [] = acc ∷ acl
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go acc acl delims (x ∷ xs) with findCharIndex 0 x delims
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... | nothing = go (x ∷ acc) acl delims xs
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... | _ = go [] (acc ∷ acl) delims xs |