- mk_sum ((expr, lty) : es)
- = let (alts, rty) = mk_sum es
- in
- (mkConApp left_dc [Type lty, Type rty, expr]
- : [mkConApp right_dc [Type lty, Type rty, alt] | alt <- alts],
- mkTyConApp plus_tc [lty, rty])
+ mk_sum es = (zipWith mk_alt (tyConDataCons sum_tc) exprs,
+ mkTyConApp sum_tc tys)
+ where
+ (exprs, tys) = unzip es
+ sum_tc = sum_tcs (length es)
+ mk_alt dc expr = mkConApp dc (map Type tys ++ [expr])
+
+ mk_prod [] = (Var unitDataConId, unitTy)
+ mk_prod [(expr, ty)] = (expr, ty)
+ mk_prod es = (mkConApp prod_dc (map Type tys ++ exprs),
+ mkTyConApp prod_tc tys)
+ where
+ (exprs, tys) = unzip es
+ prod_tc = prod_tcs (length es)
+ [prod_dc] = tyConDataCons prod_tc
+
+ mk_embed expr = (mkConApp embed_dc [Type ty, expr],
+ mkTyConApp embed_tc [ty])
+ where ty = exprType expr