fix(py): min/max: support arg of Comparable

src/pylib/builtins/min_max.nim

@@ -30,7 +30,10 @@ template addKeyIfExist(result; kw) =
     result.add nnkExprEqExpr.newTree(keyId, kw[keyId])
 
 type
-  PyLibKey*[T, R] = proc (x: T): R
+  Comparable* = concept a, b
+    ## internal.
+    a < b is bool
+  PyLibKey*[T; R: Comparable] = proc (x: T): R
 
 template withDefaultImpl(resultExpr){.dirty.} =
   result = default
@@ -53,8 +56,11 @@ template cmpByKey[T](dir, key; a, b: T): T =
   if dir(key(a), key(b)): a
   else: b
 
+template asis[T](x: T): T = x
+
 template gen(sym, dir, symName){.dirty.} =
-  ## min/max(a, b) is alreadly defined by `system`
+  ## min/max(a, b) for builtin types is alreadly defined by `system`
+  func sym*[T: Comparable](a, b: T): T = cmpByKey(dir, asis, a, b)
   func sym*[T; R](a, b: T; key: PyLibKey[T, R]): T = cmpByKey(dir, key, a, b)
   func sym*[T](a, b: T; key: NoneType): T = sym(a, b)
 
@@ -79,6 +85,13 @@ template gen(sym, dir, symName){.dirty.} =
     withDefaultImpl cmpByKey(dir, key, result, i)
 
   macro sym*(kwargs: varargs[untyped]): untyped =
+    ## for argument list: `(*args, key)`
+    ## 
+    ## raises *compile-time* `TypeError` when Python does so, in cases:
+    ## 
+    ## - `()`                       # no arg
+    ## - `(arg[, default][, key])`  # only one arg
+    ## - `(*args, default[, key])`  # both args and default are given
     let nka = kwargs.len
 
     var