Add more examples

Author: alexarice

README.md

@@ -37,3 +37,8 @@ Examples of common gates (and of the syntax) can be found in [examples/gates.ph]
 ```bash
 cargo run -- --file examples/gates.ph
 ```
+The examples folder also contains programs for:
+- Grover's algorithm (for finding the element 0000)
+- QFT (up to 4 qubits)
+- GHZ state preparation
+- An example circuit translation with swap gates

examples/ghz.ph

@@ -0,0 +1,7 @@
+gate Z = if let |1> then -1,
+gate X = if let |-> then -1,
+gate S = sqrt(Z),
+gate Y = if let S . |-> then -1,
+gate H = if let sqrt(sqrt(Y)) . |1> then -1,
+
+H x id4; if let |1> x id4 then X x X x X x X

examples/grover.ph

@@ -0,0 +1,4 @@
+gate oracle = if let |0000> then -1,
+gate diffusion = if let |++++> then -1,
+
+oracle ; diffusion

examples/qft.ph

@@ -0,0 +1,16 @@
+gate Z = if let |1> then -1,
+gate X = if let |-> then -1,
+gate S = sqrt(Z),
+gate Y = if let S . |-> then -1,
+gate H = if let sqrt(sqrt(Y)) . |1> then -1,
+gate R2 = if let |1> then i,
+gate R3 = if let |1> then ph(0.25pi),
+gate R4 = if let |1> then ph(0.125pi),
+
+gate QFT0 = id0,
+gate QFT1 = H x id0; if let |1> x id0 then id0; id x QFT0,
+gate QFT2 = H x id; if let |1> x id1 then R2; id x QFT1,
+gate QFT3 = H x id2; if let |1> x id2 then R2 x R3; id x QFT2,
+gate QFT4 = H x id3; if let |1> x id3 then R2 x R3 x R4; id x QFT3,
+
+QFT4

src/raw_syntax/term.rs

@@ -79,7 +79,7 @@ pub enum AtomRInner<S> {
         /// Pattern to match on in "if let"
         pattern: PatternR<S>,
         /// Body of the "if let"
-        inner: Box<AtomR<S>>,
+        inner: Box<TensorR<S>>,
     },
     /// Top level symbol, a named gate
     Gate(Name),
@@ -267,7 +267,7 @@ impl HasParser for AtomRInner<Range<usize>> {
 		_: multispace1,
 		_: "then".context(StrContext::Expected(StrContextValue::StringLiteral("then"))),
 		_: multispace1,
-		AtomR::parser)),
+		TensorR::parser)),
             )
             .map(|(pattern, inner)| AtomRInner::IfLet {
                 pattern,

src/typecheck.rs

@@ -3,11 +3,7 @@
 use std::collections::HashMap;
 
 use crate::{
-    raw_syntax::{
-        PatternR, TermR,
-        pattern::PatTensorR,
-        term::{AtomR, TensorR},
-    },
+    raw_syntax::{PatternR, TermR, pattern::PatTensorR, term::TensorR},
     text::Name,
     typed_syntax::{PatternType, TermT, TermType},
 };
@@ -33,7 +29,7 @@ pub enum TypeCheckError<S> {
         /// Type of pattern
         pty: PatternType,
         /// Body term
-        t: AtomR<S>,
+        t: TensorR<S>,
         /// Type of body term
         tty: TermType,
     },

src/typed_syntax/term.rs

@@ -217,7 +217,7 @@ impl TermT {
             TermT::Phase(phase) => AtomRInner::Phase(*phase),
             TermT::IfLet { pattern, inner } => AtomRInner::IfLet {
                 pattern: pattern.to_raw(),
-                inner: Box::new(inner.to_raw_atom()),
+                inner: Box::new(inner.to_raw_tensor()),
             },
             TermT::Gate { name, .. } => AtomRInner::Gate(name.to_owned()),
             TermT::Inverse(inner) => AtomRInner::Inverse(Box::new(inner.to_raw_atom())),