typ

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 Go to latest Published: Feb 6, 2024 License: BSD-2-Clause Imports: 10 Imported by: 9

README

xelf/typ

Xelf is a typed language. We use a kind bitset from package knd to describe many details. All types can have a type id and a name, type variables and references use these internally for resolution. Complex types need to store additional information in specialized type bodies.

Types are naturally enclosed in angular brackets. However the brackets can be omitted in contexts where a type is expected and the type description fits in one symbol.

Type alternatives represent type choices and are otherwise used internally for resolution. Nullable types are most common form of type alternative and have a special prefix notation using ?:

  (eq <alt int none> int?)

Type variables, references and selections use the at-sign '@' to separate kind from identifier.

  `@`       type variable with auto id
  `@1`      type variable with id 1
  `num@1`   type variable with constraint num
  `@ref`    type reference
  `num@ref` named num type
  `.sel`    local type selection

Variable and reference types must be instantiated by the type system by calling Sys.Inst, that means variables get fresh ids, and references and selections are resolved.

Types with element bodies are frequently used, we therefor provide a shorthand notation that joins the type and element with the pipe '|' character.

  (eq list|int@1? <list <alt@1 int none>>)
  sym|typ|list|dict|int

Parameter types like obj can have optional fields where names may ends in a question mark '?'. This means if the field has a zero value it can be omitted when serialized or sent to database. This is orthogonal to whether the type is optional.

  (obj name?:str opt?:str? (<> explicit optional (pointer to) string))

Documentation

Overview

Package typ provides a xelf type implementation, parser and inference system.

Index

Constants

This section is empty.

Variables

View Source 
var (
	Void = Type{Kind: knd.Void}
	None = Type{Kind: knd.None}
	Bool = Type{Kind: knd.Bool}
	Num  = Type{Kind: knd.Num}
	Int  = Type{Kind: knd.Int}
	Real = Type{Kind: knd.Real}
	Char = Type{Kind: knd.Char}
	Str  = Type{Kind: knd.Str}
	Raw  = Type{Kind: knd.Raw}
	UUID = Type{Kind: knd.UUID}
	Time = Type{Kind: knd.Time}
	Span = Type{Kind: knd.Span}

	Lit    = Type{Kind: knd.Lit}
	Typ    = Type{Kind: knd.Typ}
	VarTyp = Type{Kind: knd.Typ | knd.Var, ID: -1}
	Sym    = Type{Kind: knd.Sym}
	Tag    = Type{Kind: knd.Tag}
	Tupl   = Type{Kind: knd.Tupl}
	Call   = Type{Kind: knd.Call}
	Exp    = Type{Kind: knd.Exp}

	Idxr = Type{Kind: knd.Idxr}
	Keyr = Type{Kind: knd.Keyr}
	List = Type{Kind: knd.List}
	Dict = Type{Kind: knd.Dict}

	Data = Type{Kind: knd.Data}
	Spec = Type{Kind: knd.Spec}
	All  = Type{Kind: knd.All}
	Any  = Type{Kind: knd.Any}
)
View Source 
var (
	ErrAssign    = fmt.Errorf("cannot assign")
	ErrIdxBounds = fmt.Errorf("index out of bounds")
)
View Source 
var WrapNull = func(t Type) *Wrap { return &Wrap{Typ: t} }

Functions

This section is empty.

Types

type AltBody 

type AltBody struct {
	Alts []Type
}

AltBody contains compound type alternatives.

func (*AltBody) EqualBody 

func (b *AltBody) EqualBody(o Body, h Hist) bool

type AstVal 

type AstVal struct{ ast.Ast }

func (*AstVal) As 

func (v *AstVal) As(t Type) (LitVal, error)

func (*AstVal) Assign 

func (v *AstVal) Assign(o LitVal) error

func (*AstVal) MarshalJSON 

func (v *AstVal) MarshalJSON() ([]byte, error)

func (*AstVal) Mut 

func (v *AstVal) Mut() LitMut

func (*AstVal) New 

func (v *AstVal) New() LitMut

func (*AstVal) Nil 

func (v *AstVal) Nil() bool

func (*AstVal) Parse 

func (v *AstVal) Parse(a ast.Ast) error

func (*AstVal) Print 

func (v *AstVal) Print(p *bfr.P) error

func (*AstVal) Ptr 

func (v *AstVal) Ptr() interface{}

func (*AstVal) String 

func (v *AstVal) String() string

func (*AstVal) Type 

func (v *AstVal) Type() Type

func (*AstVal) UnmarshalJSON 

func (v *AstVal) UnmarshalJSON(b []byte) (err error)

func (*AstVal) Value 

func (v *AstVal) Value() LitVal

func (*AstVal) Zero 

func (v *AstVal) Zero() bool

type Body 

type Body interface {
	EqualBody(Body, Hist) bool
}

Body contains additional type information.

type BodyPair 

type BodyPair struct{ A, B Body }

type Const 

type Const struct {
	Name string
	Key  string
	Val  int64
}

Const describes a named constant value for an enum or bits type.

func C 

func C(name string, v int64) Const

type ConstBody 

type ConstBody struct {
	Consts []Const
}

ConstBody contains a name and a list of constants for the enum and bits types.

func (*ConstBody) EqualBody 

func (b *ConstBody) EqualBody(o Body, h Hist) bool

func (*ConstBody) FindKeyIndex 

func (b *ConstBody) FindKeyIndex(key string) int

func (*ConstBody) FindValIndex 

func (b *ConstBody) FindValIndex(val int64) int

type EditFunc 

type EditFunc func(e *Editor) (Type, error)

EditFunc edits a type and returns the result or an error. A copy editor expects returned types that differ from the input to be already copied.

type Editor 

type Editor struct {
	Type
	Parent *Editor
	// contains filtered or unexported fields
}

Editor is type context used to edit type. It references the parents type context.

type Hist 

type Hist []BodyPair

type LitMut 

type LitMut interface {
	LitVal
	// New returns a fresh mutable value of the same type or an error.
	New() LitMut
	// Ptr returns a pointer to the underlying value for interfacing with other go tools.
	Ptr() interface{}
	// Assign assigns the given value to this mutable or returns an error.
	Assign(LitVal) error
	// Parse reads the given ast into this mutable or returns an error.
	// The registry parameter is strictly optional, proxies should bring a registry if required.
	Parse(ast.Ast) error
}

LitMut is the common interface of all mutable literal values see lit.Mut for more information. Mutable values should have an UnmarshalJSON method unless the base type is natively supported. This interface does in principle belong to the lit package.

type LitVal 

type LitVal interface {
	Type() Type
	// Nil returns whether this is a null value.
	Nil() bool
	// Zero returns whether this is a zero value.
	Zero() bool
	// Value returns a simple value restricted to these types: Null, Bool, Int, Real, Str, Raw,
	// UUID, Time, Span, Type, Idxr, Keyr and *SpecRef.
	Value() LitVal
	// Mut returns the effective mutable itself or a new mutable for this value.
	Mut() LitMut
	// As returns the same or a new value with the given type or an error.
	// The value type must be convertible to the new type and the value conversion must succeed.
	As(Type) (LitVal, error)
	// String returns a string content for char literals and xelf format for other literals.
	// Use bfr.String(v) to get quoted char literals.
	String() string
	// Print writes this literal to the given printer or returns an error.
	Print(*bfr.P) error
	// MarshalJSON returns the literal as json bytes
	MarshalJSON() ([]byte, error)
}

LitVal is the common interface of all literal values see lit.Val for more information. This interface does in principle belong to the lit package.

type Lookup 

type Lookup = func(string) (Type, error)

Lookup is the type registry interface used to look up type references.

type Null 

type Null struct{}

func (Null) As 

func (Null) As(t Type) (LitVal, error)

func (Null) Len 

func (Null) Len() int

func (Null) MarshalJSON 

func (Null) MarshalJSON() ([]byte, error)

func (Null) Mut 

func (Null) Mut() LitMut

func (Null) Nil 

func (Null) Nil() bool

func (Null) Print 

func (Null) Print(p *bfr.P) error

func (Null) String 

func (Null) String() string

func (Null) Type 

func (Null) Type() Type

func (Null) Value 

func (Null) Value() LitVal

func (Null) Zero 

func (Null) Zero() bool

type Param 

type Param struct {
	Name string
	Key  string
	Type
}

Param describes a obj field or spec parameter.

func P 

func P(name string, t Type) Param

func (Param) IsOpt 

func (p Param) IsOpt() bool

type ParamBody 

type ParamBody struct {
	Params []Param
}

ParamBody contains a name and a list of parameters for obj and spec types.

func (*ParamBody) EqualBody 

func (b *ParamBody) EqualBody(o Body, h Hist) bool

func (*ParamBody) FindKeyIndex 

func (b *ParamBody) FindKeyIndex(key string) int

type Sys 

type Sys struct {
	MaxID int32
	Map   map[int32]Type
}

Sys is the resolution context used to instantiate, bind, update and unify types. Type unification is part of sys, because it needs close access to the type variable bindings.

func NewSys 

func NewSys() *Sys

NewSys creates and returns an empty type system using the given type registry.

func (*Sys) Bind 

func (sys *Sys) Bind(t Type) Type

Bind binds type t using an existing id or sets a new id and returns the update type.

func (*Sys) Free 

func (c *Sys) Free(t Type, res []Type) []Type

Free appends all unbound type variables in t to res and returns the result.

func (*Sys) Get 

func (sys *Sys) Get(id int32) Type

Get returns the bound type for id or void.

func (*Sys) Inst 

func (sys *Sys) Inst(lup Lookup, t Type) (Type, error)

Inst instantiates all vars in t for sys and returns the result or an error.

func (*Sys) Unify 

func (sys *Sys) Unify(t, h Type) (_ Type, err error)

Unify unifies type t and h and returns the result or an error. Type unification in this context means that we have two types that should describe the same type. We then check where these descriptions overlap and use the result instead of the input types.

func (*Sys) Update 

func (sys *Sys) Update(t Type) (Type, error)

Update updates all vars and refs in t with the currently bound types and returns the result.

type Type 

type Type struct {
	Kind knd.Kind
	ID   int32
	Ref  string
	Body
}

Type describes the shape of a xelf expression, literal or value.

func Alt 

func Alt(ts ...Type) Type

func Bits 

func Bits(n string, cs ...Const) Type

func CallOf 

func CallOf(t Type) Type

func Clone 

func Clone(r Type) Type

func ContEl 

func ContEl(t Type) Type

func Deopt 

func Deopt(t Type) Type

func DictOf 

func DictOf(t Type) Type

func Edit 

func Edit(t Type, f EditFunc) (Type, error)

Copy edits type t and all offspring types with f and returns the result or an error.

func El 

func El(t Type) Type

func ElemTupl 

func ElemTupl(t Type) Type

func Enum 

func Enum(n string, cs ...Const) Type

func Form 

func Form(name string, ps ...Param) Type

func Func 

func Func(name string, ps ...Param) Type

func IdxrOf 

func IdxrOf(t Type) Type

func KeyrOf 

func KeyrOf(t Type) Type

func Last 

func Last(t Type) Type

Last returns the last element type if t is a list or dict type otherwise t is returned as is.

func ListOf 

func ListOf(t Type) Type

func LitOf 

func LitOf(t Type) Type

func Obj 

func Obj(n string, ps ...Param) Type

func Opt 

func Opt(t Type) Type

func ParamTupl 

func ParamTupl(ps ...Param) Type

func Parse 

func Parse(str string) (Type, error)

Parse parses str and returns a type or an error.

func ParseAst 

func ParseAst(a ast.Ast) (Type, error)

ParseAst parses a as type and returns it or an error.

func ParseSym 

func ParseSym(raw string, src ast.Src) (Type, error)

func Read 

func Read(r io.Reader, name string) (Type, error)

Read parses named reader r and returns a type or an error.

func Ref 

func Ref(name string) Type

func Res 

func Res(t Type) Type

func Sel 

func Sel(sel string) Type

func Select 

func Select(t Type, path string) (Type, error)

Select reads path and returns the selected type from t or an error.

func SelectIdx 

func SelectIdx(t Type, idx int) (Type, error)

func SelectKey 

func SelectKey(t Type, key string) (Type, error)

func SelectList 

func SelectList(t Type, p cor.Path) (r Type, err error)

func SelectPath 

func SelectPath(t Type, path cor.Path) (r Type, err error)

SelectPath returns the selected type from t or an error.

func SymOf 

func SymOf(t Type) Type

func TagOf 

func TagOf(t Type) Type

func ToType 

func ToType(v LitVal) (t Type, err error)

func TuplEl 

func TuplEl(t Type) (Type, int)

func TypOf 

func TypOf(t Type) Type

func Var 

func Var(id int32, t Type) Type

func WithID 

func WithID(id int32, t Type) Type

func WithRef 

func WithRef(r string, t Type) Type

func (Type) As 

func (t Type) As(o Type) (LitVal, error)

func (*Type) Assign 

func (t *Type) Assign(p LitVal) error

func (Type) AssignableTo 

func (t Type) AssignableTo(dst Type) bool

AssignableTo returns whether *all* values represented by type t can be assigned to dst.

func (Type) ConvertibleTo 

func (t Type) ConvertibleTo(dst Type) bool

ConvertibleTo returns whether *any* value represented by type t can be assigned to dst. That means char is convertible to time, but str is not.

func (Type) Equal 

func (t Type) Equal(o Type) bool

Equal returns whether type t and o are identical.

func (*Type) EqualBody 

func (t *Type) EqualBody(b Body, h Hist) bool

A *Type itself can be used as element body for expression and container types.

func (Type) EqualHist 

func (t Type) EqualHist(o Type, h Hist) bool

func (Type) MarshalJSON 

func (t Type) MarshalJSON() ([]byte, error)

func (Type) Mut 

func (t Type) Mut() LitMut

func (*Type) New 

func (*Type) New() LitMut

func (Type) Nil 

func (Type) Nil() bool

func (*Type) Parse 

func (t *Type) Parse(a ast.Ast) error

func (Type) Print 

func (t Type) Print(b *bfr.P) error

func (*Type) Ptr 

func (t *Type) Ptr() interface{}

func (Type) ResolvableTo 

func (t Type) ResolvableTo(dst Type) bool

ResolvableTo returns whether the resolved value of t is convertible to the resolved dest. That call|char, call or exp are all possibly resolvable to time, but not call|str.

func (Type) String 

func (t Type) String() string

func (Type) Type 

func (t Type) Type() Type

func (*Type) UnmarshalJSON 

func (t *Type) UnmarshalJSON(b []byte) error

func (Type) Value 

func (t Type) Value() LitVal

func (Type) Zero 

func (t Type) Zero() bool

type Wrap 

type Wrap struct {
	Typ Type
	OK  bool
	Val LitMut
}

Wrap is versatile literal value wrapper. It can generalize the type of a mutable value. It does also provide automatic optional behaviour, a mutable 'any' value and lazy value support.

func (Wrap) As 

func (w Wrap) As(t Type) (LitVal, error)

func (*Wrap) Assign 

func (w *Wrap) Assign(v LitVal) error

func (*Wrap) MarshalJSON 

func (w *Wrap) MarshalJSON() ([]byte, error)

func (*Wrap) Mut 

func (w *Wrap) Mut() LitMut

func (Wrap) New 

func (w Wrap) New() (v LitMut)

func (*Wrap) Nil 

func (w *Wrap) Nil() bool

func (*Wrap) Parse 

func (w *Wrap) Parse(a ast.Ast) error

func (*Wrap) Print 

func (w *Wrap) Print(p *bfr.P) error

func (*Wrap) Ptr 

func (w *Wrap) Ptr() interface{}

func (*Wrap) String 

func (w *Wrap) String() string

func (*Wrap) Type 

func (w *Wrap) Type() Type

func (*Wrap) UnmarshalJSON 

func (w *Wrap) UnmarshalJSON(b []byte) error

func (*Wrap) Unwrap 

func (w *Wrap) Unwrap() LitVal

func (*Wrap) Value 

func (w *Wrap) Value() LitVal

func (*Wrap) Zero 

func (w *Wrap) Zero() bool

Source Files

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