@@ -27,7 +27,7 @@ type and ``n`` is the length of the list and can be an arbitrary term.
27When types can contain values, and where those values describe
27When types can contain values, and where those values describe
28properties, for example the length of a list, the type of a function
28properties, for example the length of a list, the type of a function
29can begin to describe its own properties. Take for example the
29can begin to describe its own properties. Take for example the
30−concatenatation of two lists. This operation has the property that the
30+concatenation of two lists. This operation has the property that the
31resulting list's length is the sum of the lengths of the two input
31resulting list's length is the sum of the lengths of the two input
32lists. We can therefore give the following type to the ``app``
32lists. We can therefore give the following type to the ``app``
33function, which concatenates vectors:
33function, which concatenates vectors: