refactor: make truncate and padRight take irrelevant argument

Author: jamesmckinna

CHANGELOG.md

@@ -15,6 +15,12 @@ Non-backwards compatible changes
 Minor improvements
 ------------------
 
+* The types of `Data.Vec.Base.{truncate|padRight}` have been weakened so
+  that the argument of type `m ≤ n` is marked as irrelevant. This should be
+  backwards compatible, but does change the equational behaviour of these
+  functions to be more eager, because no longer blocking on pattern matching
+  on that argument.
+
 Deprecated modules
 ------------------
 

src/Data/Vec/Base.agda

@@ -289,14 +289,14 @@ uncons (x ∷ xs) = x , xs
 -- Operations involving ≤
 
 -- Take the first 'm' elements of a vector.
-truncate : ∀ {m n} → m ≤ n → Vec A n → Vec A m
-truncate {m = zero} _ _    = []
-truncate (s≤s le) (x ∷ xs) = x ∷ (truncate le xs)
+truncate : .(m ≤ n) → Vec A n → Vec A m
+truncate {m = zero}  _  _        = []
+truncate {m = suc _} le (x ∷ xs) = x ∷ (truncate (s≤s⁻¹ le) xs)
 
 -- Pad out a vector with extra elements.
-padRight : ∀ {m n} → m ≤ n → A → Vec A m → Vec A n
-padRight z≤n      a xs       = replicate _ a
-padRight (s≤s le) a (x ∷ xs) = x ∷ padRight le a xs
+padRight : .(m ≤ n) → A → Vec A m → Vec A n
+padRight {n = _}     _  a []       = replicate _ a
+padRight {n = suc _} le a (x ∷ xs) = x ∷ padRight (s≤s⁻¹ le) a xs
 
 ------------------------------------------------------------------------
 -- Operations for converting between lists