knave 0.14.11

A Lisp programming language for humans and agents that infers types and ownership and compiles to readable Rust
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136

use super::rust_types::RustTypeTable;
use super::ty::Type;
use crate::core::PrimitiveType;

#[derive(Clone, Copy)]
pub struct ViewCoercion<'a> {
    view: &'a Type,
    owned: &'a Type,
}

impl<'a> ViewCoercion<'a> {
    pub fn new(view: &'a Type, owned: &'a Type) -> Self {
        Self { view, owned }
    }

    pub fn views_string(&self) -> bool {
        matches!(
            (self.view, self.owned),
            (
                Type::Primitive(PrimitiveType::Str),
                Type::Primitive(PrimitiveType::String)
            )
        )
    }

    pub fn viewed_items(&self, rust_types: &RustTypeTable) -> Option<Vec<(Type, Type)>> {
        match (self.view, self.owned) {
            (Type::Named(slice, items), Type::Named(vector, elements))
                if rust_types.is_slice(*slice) && rust_types.is_vector(*vector) =>
            {
                Some(
                    items
                        .iter()
                        .cloned()
                        .zip(elements.iter().cloned())
                        .collect(),
                )
            }
            _ => None,
        }
    }
}

#[cfg(test)]
mod tests {
    use super::ViewCoercion;
    use crate::core::PrimitiveType;
    use crate::types::{Type, TypedProgram, TypedSource};

    struct ViewFixture {
        program: TypedProgram,
    }

    impl ViewFixture {
        const SOURCE: &str = "
            (defn readings ((items (vec i64))) items)
            (defn window ((items (ref (slice u8)))) (len items))
            (defn reading ((value (option i64))) value)
            (defn main () (println \"Leaf\"))";

        fn new() -> Self {
            Self {
                program: TypedSource::expand(Self::SOURCE).typed(),
            }
        }

        fn viewed_items(&self, view: &Type, owned: &Type) -> Option<Vec<(Type, Type)>> {
            ViewCoercion::new(view, owned).viewed_items(&self.program.rust_types)
        }

        fn parameter(&self, function: &str) -> Type {
            let definition = self
                .program
                .modules
                .iter()
                .flat_map(|module| &module.definitions)
                .find(|definition| self.program.bindings.get(definition.binding).name() == function)
                .expect("the source defines the function");
            let Type::Function(_, parameters, _) = &definition.scheme.body else {
                panic!("a defn has a function type");
            };
            parameters[0].referent().clone()
        }
    }

    #[test]
    fn a_slice_relates_its_items_to_the_elements_of_a_vector() {
        let fixture = ViewFixture::new();
        let items =
            fixture.viewed_items(&fixture.parameter("window"), &fixture.parameter("readings"));
        assert_eq!(
            items,
            Some(vec![(
                Type::Primitive(PrimitiveType::U8),
                Type::Primitive(PrimitiveType::I64)
            )])
        );
    }

    #[test]
    fn a_type_that_is_not_a_slice_views_no_vector() {
        let fixture = ViewFixture::new();
        assert!(
            fixture
                .viewed_items(
                    &fixture.parameter("reading"),
                    &fixture.parameter("readings")
                )
                .is_none()
        );
    }

    #[test]
    fn a_slice_views_no_type_that_is_not_a_vector() {
        let fixture = ViewFixture::new();
        assert!(
            fixture
                .viewed_items(&fixture.parameter("window"), &fixture.parameter("reading"))
                .is_none()
        );
    }

    #[test]
    fn a_str_views_a_string() {
        let view = Type::Primitive(PrimitiveType::Str);
        let owned = Type::Primitive(PrimitiveType::String);
        assert!(ViewCoercion::new(&view, &owned).views_string());
    }

    #[test]
    fn a_string_does_not_view_a_str() {
        let view = Type::Primitive(PrimitiveType::String);
        let owned = Type::Primitive(PrimitiveType::Str);
        assert!(!ViewCoercion::new(&view, &owned).views_string());
    }
}