added param type check + some functions

src/vec.typ

@@ -1,20 +1,43 @@
+#let is-vec(vec) = {
+  if type(vec) != dictionary {return false}
+  if vec.at("type", default: none) != "vector" {return false}
+  return true
+}
+
+#let _check(vec) = {
+  if not is-vec(vec) {
+    panic("Argument is not a vector")
+  }
+}
+
 #let vec(..args) = {
   let comps = args.pos()
   let size = comps.len()
   return (
+    type: "vector",
     comps: comps,
     size: size
   )
 }
 
+#let copy(vec) = {
+  _check(vec)
+  return vec(..vec.comps)
+}
+
 #let of-size(size) = {
   let comps = (0,) * size
   return vec(..comps)
 }
 
-#let display(vec) = math.vec(..vec.comps.map(c => [#c]))
+#let display(vec) = {
+  _check(vec)
+  math.vec(..vec.comps.map(c => [#c]))
+}
 
 #let add(vec1, vec2) = {
+  _check(vec1)
+  _check(vec2)
   if vec1.size != vec2.size {
     panic("Can't add vectors of size " + str(vec1.size) + " and " + str(vec2.size))
   }
@@ -24,6 +47,8 @@
 }
 
 #let sub(vec1, vec2) = {
+  _check(vec1)
+  _check(vec2)
   if vec1.size != vec2.size {
     panic("Can't subtract vectors of size " + str(vec1.size) + " and " + str(vec2.size))
   }
@@ -33,6 +58,8 @@
 }
 
 #let dot(vec1, vec2) = {
+  _check(vec1)
+  _check(vec2)
   if vec1.size != vec2.size {
     panic("Can't compute dot product of vectors of size " + str(vec1.size) + " and " + str(vec2.size))
   }
@@ -45,6 +72,8 @@
 }
 
 #let cross(vec1, vec2) = {
+  _check(vec1)
+  _check(vec2)
   if vec1.size != 3 or vec2.size != 3 {
     panic("Can only compute cross product of vectors of size 3")
   }
@@ -60,6 +89,7 @@
 }
 
 #let to-mat(vec) = {
+  _check(vec)
   import "mat.typ" as _mat
   return _mat.mat(..vec.comps.map(c => (c,)))
 }