builtins: add normalized switch-1

1 files changed, 33 insertions, 1 deletions

diff --git a/alv/builtins.moon b/alv/builtins.moon
index 0d188f9..56a6eea 100644
--- a/alv/builtins.moon
+++ b/alv/builtins.moon
@@ -341,7 +341,7 @@ switch_ = Constant.meta
 When only a single value is provided, it must be an array and is indexed as above."
 
   value: class extends Op
-    pattern = (sig.num / sig.bool / evt.num / evt.bool / evt.bang) + any!!*0
+    pattern = (any.num / any.bool / evt.bang) + any!!*0
     setup: (inputs) =>
       { i, values } = pattern\match inputs
 
@@ -387,6 +387,37 @@ When only a single value is provided, it must be an array and is indexed as abov
       with Op.vis @
         .step = @state
 
+switch_norm = Constant.meta
+  meta:
+    name: 'switch-1'
+    summary: "Switch between multiple inputs based on normalized i."
+    examples: { '(switch-1 i v1 v2…)', '(switch i arr)' }
+    description: "
+Like `switch`, but numeric indexes are in the range `[0, 1[`."
+
+  value: class extends switch_.value
+    tick: =>
+      { :i, :values } = @inputs
+
+      length = @length or #values
+
+      if i\type! == T.bang
+        if i\dirty!
+          @state += 1
+          @state = @state % length
+      else
+        @state = switch i!
+          when true then 0
+          when false then 1
+          else (math.floor i! * length) % length
+
+      @out\set if @length
+        val = values[1]!
+        val and val[@state + 1]
+      else
+        val = values[@state + 1]
+        val and val!
+
 trace_ = Constant.meta
   meta:
     name: 'trace='
@@ -723,6 +754,7 @@ Constant.meta
     'if': if_
     'when': when_
     'switch': switch_
+    'switch-1': switch_norm
 
     '=': to_const
     '~': to_sig