rhiannon morris
773f6372ea
...as long as they are all compatible with the target.
for example, given ω.n : ℕ:
```
case double_it? return ℕ of {
'true ⇒ plus n n;
'false ⇒ n
}
```
79 lines
2.1 KiB
Idris
79 lines
2.1 KiB
Idris
module Quox.Syntax.Qty
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import Quox.Pretty
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import Quox.Name
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import public Quox.Decidable
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import Data.DPair
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%default total
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public export
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interface Eq q => IsQty q where
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zero, one : q
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(+), (*) : q -> q -> q
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lub : q -> q -> Maybe q
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||| true if bindings of this quantity will be erased
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||| and must not be runtime relevant
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IsZero : Pred q
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isZero : Dec1 IsZero
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zeroIsZero : IsZero zero
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||| ``p `Compat` q`` if it is ok for a binding of quantity `q` to be used
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||| exactly `p` times. e.g. ``1 `Compat` 1``, ``1 `Compat` ω``.
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||| if ``π `lub` ρ`` exists, then both `π` and `ρ` must be compatible with it
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Compat : Rel q
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compat : Dec2 Compat
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||| true if it is ok for this quantity to appear for the
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||| subject of a typing judgement [@qtt, §2.3].
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IsSubj : Pred q
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isSubj : Dec1 IsSubj
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zeroIsSubj : forall pi. IsZero pi -> IsSubj pi
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oneIsSubj : IsSubj one
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timesSubj : forall pi, rh. IsSubj pi -> IsSubj rh -> IsSubj (pi * rh)
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||| true if it is ok for a global definition to have this
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||| quantity. so not exact usage counts, maybe.
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IsGlobal : Pred q
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isGlobal : Dec1 IsGlobal
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zeroIsGlobal : forall pi. IsZero pi -> IsGlobal zero
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||| prints in a form that can be a suffix of "case"
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prettySuffix : Pretty.HasEnv m => q -> m (Doc HL)
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public export
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0 SQty : (q : Type) -> IsQty q => Type
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SQty q = Subset q IsSubj
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public export %inline
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szero : IsQty q => SQty q
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szero = Element zero $ zeroIsSubj zeroIsZero
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public export %inline
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sone : IsQty q => SQty q
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sone = Element one oneIsSubj
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||| "σ ⨴ π"
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|||
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||| ``sg `subjMult` pi`` is equal to `pi` if it is zero, otherwise it
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||| is equal to `sg`.
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public export %inline
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subjMult : IsQty q => SQty q -> q -> SQty q
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subjMult sg pi = case isZero pi of
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Yes y => Element pi $ zeroIsSubj y
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No _ => sg
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public export
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0 GQty : (q : Type) -> IsQty q => Type
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GQty q = Subset q IsGlobal
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public export %inline
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gzero : IsQty q => GQty q
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gzero = Element zero $ zeroIsGlobal zeroIsZero
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export %inline
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globalToSubj : IsQty q => GQty q -> SQty q
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globalToSubj q = if isYes $ isZero q.fst then szero else sone
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