rules.md

規則集

ASTNode

Call

call {
    callee
    argument
}

Closure

closure {
    body[]
}

DeclRef

declref {
    name
}

OverloadedDeclRef

overloaded_declref {
    targets[]
}

VariableDecl

vardecl {
    var_name
    init
}

制約の生成規則 / constraints generation rules

Call

(argument) -> self <appfn> callee

Closure

body.last <conv> result
    where body.count == 1

DeclRef

self <bind> target

OverloadedDeclRef

disjunction(
    self <bind> targets[0],
    self <bind> targets[1],
    ...
)

VariableDecl

init <conv> var

制約の簡約規則 / constraints simplify rules

bind

primitive1 <bind> primitive2 >>
    if primitive1 == primitive2:
        *solved
    *failure

(type1) -> type2 <bind> (type3) -> type4 >>
    type1 <bind> type3
    type2 <bind> type4

fixed <bind> typevar >>
    assign(typevar, fixed)

typevar1 <bind> typevar2 >>
    merge(typevar1, typevar2)

applicative function

(arg) -> ret <appfn> callee >>
    if callee is typevar:
        *ambiguous
    if callee is function:
        arg <conv> callee.param
        ret <bind> callee.result
    *failure

conversion

primitive1 <conv> primitive2 >>
    if primitive1 == primitive2:
        *solved
    *failure

(type1) -> type2 <conv> (type3) -> type4 >>
    type3 <conv> type1 // contravariance
    type2 <conv> type4 // covariance

type1 <conv> type2
    where type2 is more optional than type1 >>
    type1 <conv VToO> type2 >>
        type1 <conv> type2.wrapped

type1 <conv> type2
    where type1 and type2 are optional >>
    type1 <conv DEQ> type2
    type1 <conv OToO> type2 >>
        type1.wrapped <conv> type2.wrapped