diagrams-core-0.2: Core libraries for diagrams EDSL




Types which have an intrinsic notion of a "local origin", i.e. things which are not invariant under translation.



class VectorSpace (V t) => HasOrigin t whereSource

Class of types which have an intrinsic notion of a "local origin", i.e. things which are not invariant under translation, and which allow the origin to be moved.

One might wonder why not just use Transformable instead of having a separate class for HasOrigin; indeed, for types which are instances of both we should have the identity

 moveOriginTo (origin .^+ v) === translate (negateV v)

The reason is that some things (e.g. vectors, Trails) are transformable but are translationally invariant, i.e. have no origin.


moveOriginTo :: Point (V t) -> t -> tSource

Move the local origin to another point.

Note that this function is in some sense dual to translate (for types which are also Transformable); moving the origin itself while leaving the object "fixed" is dual to fixing the origin and translating the diagram.


HasOrigin a => HasOrigin [a] 
VectorSpace v => HasOrigin (Point v) 
VectorSpace v => HasOrigin (NameMap v) 
(InnerSpace v, AdditiveGroup (Scalar v), Fractional (Scalar v)) => HasOrigin (Bounds v)

The local origin of a bounding function is the point with respect to which bounding queries are made, i.e. the point from which the input vectors are taken to originate.

VectorSpace v => HasOrigin (Query v m) 
(HasLinearMap v, InnerSpace v, OrderedField (Scalar v), Monoid m) => HasOrigin (AnnDiagram b v m)

Every diagram has an intrinsic "local origin" which is the basis for all combining operations.

moveOriginBy :: HasOrigin t => V t -> t -> tSource

Move the local origin by a relative vector.

moveTo :: HasOrigin t => Point (V t) -> t -> tSource

Translate the object by the translation that sends the origin to the given point. Note that this is dual to moveOriginTo, i.e. we should have

 moveTo (origin .^+ v) === moveOriginTo (origin .^- v)

For types which are also Transformable, this is essentially the same as translate, i.e.

 moveTo (origin .^+ v) === translate v