A few example types

types.dot

digraph {   
    subgraph cluster1 {
        label="Any"
        0 [ color=blue; label = "0: Var(0)" ]
        1 [ color=red; label = "1: Value((VTop, Span(5)))" ]
    }
    
    subgraph cluster2 {
        label="Never"
        4 [ color=red;  label = "4: Var(4)" ]
        5 [ color=blue; label = "5: Use((UBot, Span(8)))" ]
    }
    
    subgraph cluster3 {
        label="Any -> Never"
        8 [ label = "8: Var(8)" ]
        9 [ label = "9: Value((VTop, Span(11)))" ]
        10 [ label = "10: Var(10)" ]
        11 [ label = "11: Use((UBot, Span(12)))" ]
        12 [ color=red;  label = "12: Value((VFunc { arg: Use(8), ret: Value(10) }, Span(13)))" ]
        13 [ color=blue; label = "13: Use((UFunc { arg: Value(9), ret: Use(11) }, Span(13)))" ]
        12 -> 8 [ style=dashed ]
        12 -> 10 [ style=dashed ]
        13 -> 9 [ style=dashed ]
        13 -> 11 [ style=dashed ]
    }
    
    subgraph cluster4 {
        label="'a -> 'a"    
        14 [ label = "14: Var(14)" ]
        15 [ color=red;  label = "15: Value((VFunc { arg: Use(14), ret: Value(14) }, Span(16)))" ]
        16 [ color=blue; label = "16: Use((UFunc { arg: Value(14), ret: Use(14) }, Span(23)))" ]
        15 -> 14 [ style=dashed ]
        15 -> 14 [ style=dashed ]
        16 -> 14 [ style=dashed ]
        16 -> 14 [ style=dashed ]
    }
    
    subgraph cluster5 {
        label="{'a with x: Int}"    
        20 [ label = "20: Var(20)" ]
        21 [ color=blue; label = "21: Var(21)" ]
        22 [ label = "22: Value((VNamed(\"Int\"), Span(35)))" ]
        23 [ label = "23: Use((UNamed(\"Int\"), Span(35)))" ]
        24 [ label = "24: Use((UObj { field: Some((\"x\", Use(23))) }, Span(34)))" ]
        25 [ color=red; label = "25: Value((VObj { fields: {\"x\": Value(22)}, proto: Some(Value(20)) }, Span(36)))" ]
        21 -> 20 [ label = "" ]
        21 -> 24 [ label = "" ]
        24 -> 23 [ style=dashed ]
        25 -> 22 [ style=dashed ]
        25 -> 20 [ style=dashed ]
    }
    
    subgraph cluster6 {
        label="{x: Int, y: Int}"    
        26 [ label = "26: Var(26)" ]
        27 [ color=blue; label = "27: Var(27)" ]
        28 [ label = "28: Value((VNamed(\"Int\"), Span(40)))" ]
        29 [ label = "29: Use((UNamed(\"Int\"), Span(40)))" ]
        30 [ label = "30: Use((UObj { field: Some((\"x\", Use(29))) }, Span(39)))" ]
        31 [ label = "31: Value((VNamed(\"Int\"), Span(42)))" ]
        32 [ label = "32: Use((UNamed(\"Int\"), Span(42)))" ]
        33 [ label = "33: Use((UObj { field: Some((\"y\", Use(32))) }, Span(41)))" ]
        34 [ color=red; label = "34: Value((VObj { fields: {\"x\": Value(28), \"y\": Value(31)}, proto: None }, Span(43)))" ]
        27 -> 30 [ label = "" ]
        27 -> 33 [ label = "" ]
        30 -> 29 [ style=dashed ]
        33 -> 32 [ style=dashed ]
        34 -> 28 [ style=dashed ]
        34 -> 31 [ style=dashed ]
    }
}