diff --git a/cmd/cue/cmd/eval.go b/cmd/cue/cmd/eval.go
index 21e08fd..a8e667d 100644
--- a/cmd/cue/cmd/eval.go
+++ b/cmd/cue/cmd/eval.go
@@ -116,31 +116,31 @@
 
 		if exprs == nil {
 			v := inst.Value()
-			if flagConcrete.Bool(cmd) {
+			if flagConcrete.Bool(cmd) && !flagIgnore.Bool(cmd) {
 				if err := v.Validate(cue.Concrete(true)); err != nil {
 					exitIfErr(cmd, inst, err, false)
 					continue
 				}
 			}
 			b, _ := format.Node(getSyntax(v, syn), opts...)
-			w.Write(b)
+			_, _ = w.Write(b)
 		}
 		for _, e := range exprs {
 			if len(exprs) > 1 {
 				fmt.Fprint(w, "// ")
 				b, _ := format.Node(e)
-				w.Write(b)
+				_, _ = w.Write(b)
 				fmt.Fprintln(w)
 			}
 			v := inst.Eval(e)
-			if flagConcrete.Bool(cmd) {
+			if flagConcrete.Bool(cmd) && !flagIgnore.Bool(cmd) {
 				if err := v.Validate(cue.Concrete(true)); err != nil {
 					exitIfErr(cmd, inst, err, false)
 					continue
 				}
 			}
 			b, _ := format.Node(getSyntax(v, syn), opts...)
-			w.Write(b)
+			_, _ = w.Write(b)
 			fmt.Fprintln(w)
 		}
 	}
diff --git a/cue/errors.go b/cue/errors.go
index 73b54ae..12342c9 100644
--- a/cue/errors.go
+++ b/cue/errors.go
@@ -102,7 +102,7 @@
 
 func isIncomplete(v value) bool {
 	if err, ok := v.(*bottom); ok {
-		return err.code == codeIncomplete
+		return err.code == codeIncomplete || err.code == codeCycle
 	}
 	return false
 }
diff --git a/cue/resolve_test.go b/cue/resolve_test.go
index 920465d..eaf637f 100644
--- a/cue/resolve_test.go
+++ b/cue/resolve_test.go
@@ -466,9 +466,9 @@
 
 			c: [c[1], c[0]]
 		`,
-		out: `<0>{a: _|_((<1>.b - 100):cycle detected), ` +
-			`b: _|_((<1>.a + 100):cycle detected), ` +
-			`c: [_|_(<1>.c[1]:cycle detected),_|_(<1>.c[0]:cycle detected)]}`,
+		out: `<0>{a: (<1>.b - 100), ` +
+			`b: (<1>.a + 100), ` +
+			`c: [<1>.c[1],<1>.c[0]]}`,
 	}, {
 		desc: "resolved self-reference cycles",
 		in: `
@@ -1054,8 +1054,8 @@
 		b: a & { l: [_, "bar"] }
 		`,
 		out: `<0>{` +
-			`a: <1>{l: ["foo",_|_(<2>.v:cycle detected)], ` +
-			`v: _|_(<2>.l[1]:cycle detected)}, ` +
+			`a: <1>{l: ["foo",<2>.v], ` +
+			`v: <2>.l[1]}, ` +
 			`b: <3>{l: ["foo","bar"], v: "bar"}}`,
 	}, {
 		desc: "correct error messages",
@@ -1929,9 +1929,9 @@
 		c2: (*{a:2} | {b:2}) & c1
 		`,
 		out: `<0>{` +
-			`a1: _|_(((*0 | 1) & (<1>.a3 - <1>.a2)):cycle detected), ` +
+			`a1: ((*0 | 1) & (<1>.a3 - <1>.a2)), ` +
 			`a3: 1, ` +
-			`a2: _|_(((*0 | 1) & (<1>.a3 - <1>.a1)):cycle detected), ` +
+			`a2: ((*0 | 1) & (<1>.a3 - <1>.a1)), ` +
 			`b1: (0 | 1), ` +
 			`b2: (0 | 1), ` +
 			`c1: (<2>{a: 1, b: 2} | <3>{a: 2, b: 1}), ` +
diff --git a/cue/types.go b/cue/types.go
index 3f4fa3c..cb39921 100644
--- a/cue/types.go
+++ b/cue/types.go
@@ -1346,12 +1346,13 @@
 }
 
 type options struct {
-	concrete     bool // enforce that values are concrete
-	raw          bool // show original values
-	hasHidden    bool
-	omitHidden   bool
-	omitOptional bool
-	omitAttrs    bool
+	concrete       bool // enforce that values are concrete
+	raw            bool // show original values
+	hasHidden      bool
+	omitHidden     bool
+	omitOptional   bool
+	omitAttrs      bool
+	disallowCycles bool // implied by concrete
 }
 
 // An Option defines modes of evaluation.
@@ -1380,6 +1381,12 @@
 	}
 }
 
+// DisallowCycles forces validation in the precense of cycles, even if
+// non-concrete values are allowed. This is implied by Concrete(true).
+func DisallowCycles(disallow bool) Option {
+	return func(p *options) { p.disallowCycles = disallow }
+}
+
 // All indicates that all fields and values should be included in processing
 // even if they can be elided or omitted.
 func All() Option {
@@ -1430,7 +1437,10 @@
 	var errs errors.Error
 	v.Walk(func(v Value) bool {
 		if err := v.checkKind(v.ctx(), bottomKind); err != nil {
-			if !o.concrete && isIncomplete(v.eval(v.ctx())) {
+			if !o.concrete && isIncomplete(err) {
+				if o.disallowCycles && err.code == codeCycle {
+					errs = errors.Append(errs, v.toErr(err))
+				}
 				return false
 			}
 			errs = errors.Append(errs, v.toErr(err))
diff --git a/cue/types_test.go b/cue/types_test.go
index 326a70c..b5c9ab7 100644
--- a/cue/types_test.go
+++ b/cue/types_test.go
@@ -1092,6 +1092,22 @@
 		in:   `a: [{b: string}, 3]`,
 		opts: []Option{Concrete(true)},
 		err:  true,
+	}, {
+		desc: "allow cycles",
+		in: `
+			a: b - 100
+			b: a + 100
+			c: [c[1], c[0]]
+			`,
+	}, {
+		desc: "disallow cycles",
+		in: `
+			a: b - 100
+			b: a + 100
+			c: [c[1], c[0]]
+			`,
+		opts: []Option{DisallowCycles(true)},
+		err:  true,
 	}}
 	for _, tc := range testCases {
 		t.Run(tc.desc, func(t *testing.T) {
diff --git a/doc/ref/spec.md b/doc/ref/spec.md
index 0e3439b..b822e6c 100644
--- a/doc/ref/spec.md
+++ b/doc/ref/spec.md
@@ -2315,7 +2315,7 @@
 that `a == e`.
 
 ```
-// Config            Evaluates to
+// Config            Evaluates to (requiring concrete values)
 x: {                  x: {
     a: b + 100            a: _|_ // cycle detected
     b: a - 100            b: _|_ // cycle detected
diff --git a/doc/tutorial/basics/cycle.md b/doc/tutorial/basics/cycle.md
index 10b2206..ed30a91 100644
--- a/doc/tutorial/basics/cycle.md
+++ b/doc/tutorial/basics/cycle.md
@@ -29,7 +29,7 @@
 ```
 
 <!-- result -->
-`$ cue eval -i cycle.cue`
+`$ cue eval -i -c cycle.cue`
 ```
 x: 200
 y: 100