infer-type-constructor := λ(: base-type Type)(: body AST). (: (
   (let r 0_u64)
   (match body (
      ()
      ( (Lit( tag _ )) (
         (let rtype (and(
            (and(
               base-type
               (t2( 'Tag_s (t1 tag) ))
            ))
            (and(
               (t1 'Constant_s)
               (and(
                  (t2( 'Constructor_s (t1 tag) ))
                  (t2( 'FieldsSized_s (t1 '0_s) ))
               ))
            ))
         )))
         (index-class-of-tag( tag base-type ))
         (index-fields-of-tag( tag TAny (t1 'Nil_s) ))
         (.bind( (as (& type-constructors-index) BTreeEq<String,Type>[]) tag rtype ))
         (set r 8_u64)
      ))
      ( (App( (Lit( tag _ )) args )) (
         (let atype (type-of-s-with-fields( base-type tag args 1_u64 )))
         (mark-constructor-flat-parameters( base-type atype ))
         (if (has-forward( atype )) (
            (print 'Size\sOf\sType\sCannot\sBe\sDetermined\sDue\sTo\sForward\sReference:\s_s)
            (print tag)(print '\n_s)
            (exit 1_u64)
         ) ())
         (if (has-infinite( base-type atype )) (
            (print 'Size\sOf\sType\sIs\sInfinite:\s_s)
            (print tag)(print '\n_s)
            (exit 1_u64)
         ) ())
         (let rtype (and(
            base-type
            (t2( 'Tag_s (t1 tag) ))
         )))
         (set-type-fields( base-type atype ))
         (index-class-of-tag( tag base-type ))
         (index-fields-of-tag( tag base-type atype ))
         (.bind( (as (& type-constructors-index) BTreeEq<String,Type>[]) tag (t3( 'Arrow_s atype rtype )) ))
         (set r (sizeof-aligned atype))
         (set r (+( r 8_u64 )))
      ))
      ( _ () )
   ))
   r
) U64);