Begin removing view related code and docs

lib/guardedBase.tri

@@ -0,0 +1,24 @@
+!import "base" !Local
+!import "list" !Local
+!import "contracts" !Local
+!import "intensional" !Local
+
+-- Runtime-guarded wrappers around partial or structurally-sensitive base/list
+-- functions. Each wrapper uses the frontend @ / =@ desugaring and is exported
+-- with an advertised contract so manifests carry the contract terms.
+
+safeHead xs@(nonEmptyListOf anyC) =@anyC head xs
+safeTail xs@(nonEmptyListOf anyC) =@(listOf anyC) tail xs
+
+safeDiv a@nat? b@(andC nat? nonZero?) =@nat? div a b
+
+safeHalf n@(andC nat? evenC?) =@nat? div n 2
+
+-- last is only guaranteed to return the maximum if the input list is sorted.
+sortedMax xs@(sortedList? nat?) =@nat? last xs
+
+!export safeHead : fnContract (nonEmptyListOf anyC) anyC
+!export safeTail : fnContract (nonEmptyListOf anyC) (listOf anyC)
+!export safeDiv : fn2 nat? nonZero? nat?
+!export safeHalf : fnContract (andC nat? evenC?) nat?
+!export sortedMax : fnContract (sortedList? nat?) nat?