util.mathcompat: Module to ease reuse of math.type()

Mostly to ensure it is available during tests, as util.startup is not
invoked there

teal-src/util/datamapper.tl

@@ -19,6 +19,8 @@
 -- TODO s/number/integer/ once we have appropriate math.type() compat
 --
 
+if not math.type then require "util.mathcompat" end
+
 local st = require "util.stanza";
 local json = require"util.json"
 local pointer = require"util.jsonpointer";

teal-src/util/jsonschema.tl

@@ -8,6 +8,8 @@
 -- https://json-schema.org/draft/2020-12/json-schema-validation.html
 --
 
+if not math.type then require "util.mathcompat" end
+
 local json = require"util.json"
 local null = json.null;
 

teal-src/util/mathcompat.tl

@@ -0,0 +1,15 @@
+if not math.type then
+	local enum number_subtype
+		"float" "integer"
+	end
+	local function math_type(t:any) : number_subtype
+		if t is number then
+			if t % 1 == 0 and t ~= t+1 and t ~= t-1 then
+				return "integer"
+			else
+				return "float"
+			end
+		end
+	end
+	_G.math.type = math_type
+end