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45 Commits

Author SHA1 Message Date
Paul Cadman
2f4a3f809b
Run test suite in parallel (#2507)
## Overview

This PR makes the compiler pipeline thread-safe so that the test suite
can be run in parallel.

This is achieved by:
* Removing use of `{get, set, with}CurrentDir` functions.
* Adding locking around shared file resources like the the
global-project and internal build directory.

NB: **Locking is disabled for the main compiler target**, as it is
single threaded they are not required.

## Run test suite in parallel

To run the test suite in parallel you must add `--ta '+RTS -N -RTS'` to
your stack test arguments. For example:

```
stack test --fast --ta '+RTS -N -RTS'
```

The `-N` instructs the Haskell runtime to choose the number of threads
to use based on how many processors there are on your machine. You can
use `-Nn` to see the number of threads to `n`.

These flags are already [set in the
Makefile](e6dca22cfd/Makefile (L26))
when you or CI uses `stack test`.

## Locking

The Haskell package
[filelock](https://hackage.haskell.org/package/filelock) is used for
locking. File locks are used instead of MVars because Juvix code does
not control when new threads are created, they are created by the test
suite. This means that MVars created by Juvix code will have no effect,
because they are created independently on each test-suite thread.
Additionally the resources we're locking live on the filesystem and so
can be conveniently tagged by path.

### FileLock

The filelock library is wrapped in a FileLock effect:


e6dca22cfd/src/Juvix/Data/Effect/FileLock/Base.hs (L6-L8)

There is an [IO
interpreter](e6dca22cfd/src/Juvix/Data/Effect/FileLock/IO.hs (L8))
that uses filelock and an [no-op
interpreter](e6dca22cfd/src/Juvix/Data/Effect/FileLock/Permissive.hs (L7))
that just runs actions unconditionally.

### TaggedLock

To make the file locks simpler to use a TaggedLock effect is introduced:


e6dca22cfd/src/Juvix/Data/Effect/TaggedLock/Base.hs (L5-L11)

And convenience function:


e6dca22cfd/src/Juvix/Data/Effect/TaggedLock.hs (L28)

This allows an action to be locked, tagged by a directory that may or
may not exist. For example in the following code, an action is performed
on a directory `root` that may delete the directory before repopulating
the files. So the lockfile cannot be stored in the `root` itself.


e6dca22cfd/src/Juvix/Extra/Files.hs (L55-L60)

## Pipeline

As noted above, we only use locking in the test suite. The main app
target pipeline is single threaded and so locking is unnecessary. So the
interpretation of locks is parameterised so that locking can be disabled
e6dca22cfd/src/Juvix/Compiler/Pipeline/Run.hs (L64)
2023-11-16 16:19:52 +01:00
Łukasz Czajka
5948a38a54
Named arguments syntax with function definitions (#2494)
* Closes #2365
* Implements the syntax `f@{x1 := def1; ...; xn := defn}` and `f@?{x1 :=
def1; ..; xn := defn}`. Each definition inside the `@{..}` is an
ordinary function definition. The `@?` version allows partial
application (not all explicit named arguments need to be provided). This
subsumes the old record creation syntax.
2023-11-07 12:02:22 +01:00
Jan Mas Rovira
0943a4ab92
Dependent default values (#2446)
- Closes #2445
2023-10-27 10:19:07 +02:00
Paul Cadman
27aaf9d9f9
Add dependency on expressions in function default arguments (#2462)
Closes:
* https://github.com/anoma/juvix/issues/2461
2023-10-24 11:02:24 +02:00
Łukasz Czajka
cdfb35aaac
Arithmetic simplification (#2454)
Simplifies arithmetic expressions in the Core optimization phase,
changing e.g. `(x - 1) + 1` to `x`. Such expressions appear as a result
of compiling pattern matching on natural numbers.
2023-10-23 11:47:17 +02:00
Łukasz Czajka
272b93e595
Constant folding (#2450)
* Closes #2154 
* Evaluates closed applications with value arguments when the result
type is zero-order. For example, `3 + 4` is evaluated to `7`, and `id 3`
is evaluated to `3`, but `id id` is not evaluated because the target
type is not zero-order (it's a function type).
2023-10-20 12:03:56 +02:00
Łukasz Czajka
cbd8253afd
Instance coercions (#2444)
* Closes #2426 

A coercion from trait `T` to `T'` can be declared with the syntax
```
coercion instance
coeName {A} {{T A}} : T' A := ...
```
Coercions can be seen as instances with special resolution rules.

Coercion resolution rules
-------------------------
* If a non-coercion instance can be applied in a single instance
resolution step, no coercions are considered. No ambiguity results if
there exists some coercion which could be applied, but a non-coercion
instance exists - the non-coercion instances have priority.
* If no non-coercion instance can be applied in a single resolution
step, all minimal coercion paths which lead to an applicable
non-coercion instance are considered. If there is more than one,
ambiguity is reported.

Examples
----------

The following type-checks because:
1. There is no non-coercion instance found for `U String`.
2. There are two minimal coercion paths `U` <- `U1` and `U` <- `U2`, but
only one of them (`U` <- `U2`) ends in an applicable non-coercion
instance (`instU2` for `U2 String`).

```
trait
type U A := mkU {pp : A -> A};

trait
type U1 A := mkU1 {pp : A -> A};

trait
type U2 A := mkU2 {pp : A -> A};

coercion instance
fromU1toU {A} {{U1 A}} : U A :=
  mkU@{
    pp := U1.pp
  };

coercion instance
fromU2toU {A} {{U2 A}} : U A :=
  mkU@{
    pp := U2.pp
  };

instance
instU2 : U2 String := mkU2 id;

main : IO := printStringLn (U.pp "X")
```

The following results in an ambiguity error because:
1. There is no non-coercion instance found for `T Unit`.
2. There are two minimal coercion paths `T` <- `T1` and `T` <- `T2`,
both of which end in applicable non-coercion instances.

```
trait
type T A := mkT { pp : A → A };

trait
type T1 A := mkT1 { pp : A → A };

trait
type T2 A := mkT2 { pp : A → A };

instance
unitT1 : T1 Unit := mkT1 (pp := λ{_ := unit});

instance
unitT2 : T2 Unit := mkT2 (pp := λ{_ := unit});

coercion instance
fromT1toT {A} {{T1 A}} : T A := mkT@{
  pp := T1.pp
};

coercion instance
fromT2toT {A} {{T2 A}} : T A := mkT@{
  pp := T2.pp
};

main : Unit := T.pp unit;
```

The following type-checks, because there exists a non-coercion instance
for `T2 String`, so the coercion `fromT1toT2` is ignored during instance
resolution.

```
trait
type T1 A := mkT1 {pp : A -> A};

trait
type T2 A := mkT2 {pp : A -> A};

instance
instT1 {A} : T1 A :=
  mkT1@{
    pp := id
  };

coercion instance
fromT1toT2 {A} {{M : T1 A}} : T2 A :=
  mkT2@{
    pp := T1.pp {{M}}
  };

instance
instT2 : T2 String :=
  mkT2@{
    pp (s : String) : String := s ++str "!"
  };

main : String := T2.pp "a";
```
2023-10-19 16:00:31 +02:00
Łukasz Czajka
1260853583
Improve closure calls in the runtime (#2396)
* Closes #1653 

The running time improvement is 20-30% on benchmarks dominated by
closure calls.
2023-09-29 14:20:00 +02:00
Łukasz Czajka
08f123fa3d
Traits (#2320)
* Closes #1646 

Implements a basic trait framework. A simple instance search mechanism
is included which fails if there is more than one matching instance at
any step.

Example usage:
```
import Stdlib.Prelude open hiding {Show; mkShow; show};

trait
type Show A :=
  mkShow {
    show : A → String
  };

instance
showStringI : Show String := mkShow (show := id);

instance
showBoolI : Show Bool := mkShow (show := λ{x := if x "true" "false"});

instance
showNatI : Show Nat := mkShow (show := natToString);

showList {A} : {{Show A}} → List A → String
  | nil := "nil"
  | (h :: t) := Show.show h ++str " :: " ++str showList t;

instance
showListI {A} {{Show A}} : Show (List A) := mkShow (show := showList);

showMaybe {A} {{Show A}} : Maybe A → String
  | (just x) := "just (" ++str Show.show x ++str ")"
  | nothing := "nothing";

instance
showMaybeI {A} {{Show A}} : Show (Maybe A) := mkShow (show := showMaybe);

main : IO :=
  printStringLn (Show.show true) >>
  printStringLn (Show.show false) >>
  printStringLn (Show.show 3) >>
  printStringLn (Show.show [true; false]) >>
  printStringLn (Show.show [1; 2; 3]) >>
  printStringLn (Show.show [1; 2]) >>
  printStringLn (Show.show [true; false]) >>
  printStringLn (Show.show [just true; nothing; just false]) >>
  printStringLn (Show.show [just [1]; nothing; just [2; 3]]) >>
  printStringLn (Show.show "abba") >>
  printStringLn (Show.show ["a"; "b"; "c"; "d"]);
```

It is possible to manually provide an instance and to match on implicit
instances:
```
f {A} : {{Show A}} -> A -> String
  | {{mkShow s}} x -> s x;

f' {A} : {{Show A}} → A → String
  | {{M}} x := Show.show {{M}} x;
```

The trait parameters in instance types are checked to be structurally
decreasing to avoid looping in the instance search. So the following is
rejected:
```
type Box A := box A;

trait
type T A := mkT { pp : A → A };

instance
boxT {A} : {{T (Box A)}} → T (Box A) := mkT (λ{x := x});
```
We check whether each parameter is a strict subterm of some trait
parameter in the target. This ordering is included in the finite
multiset extension of the subterm ordering, hence terminating.
2023-09-08 12:16:43 +02:00
Jan Mas Rovira
f7382caeac
Record updates (#2263)
- Closes #1642.

This pr introduces syntax for convenient record updates.
Example:
```
type Triple (A B C : Type) :=
  | mkTriple {
      fst : A;
      snd : B;
      thd : C;
    };

main : Triple Nat Nat Nat;
main :=
  let
    p : Triple Nat Nat Nat := mkTriple 2 2 2;
    p' :
      Triple Nat Nat Nat :=
        p @Triple{
          fst := fst + 1;
          snd := snd * 3
        };
    f : Triple Nat Nat Nat -> Triple Nat Nat Nat := (@Triple{fst := fst * 10});
  in f p';
```
We write `@InductiveType{..}` to update the contents of a record. The
`@` is used for parsing. The `InductiveType` symbol indicates the type
of the record update. Inside the braces we have a list of `fieldName :=
newValue` items separated by semicolon. The `fieldName` is bound in
`newValue` with the old value of the field. Thus, we can write something
like `p @Triple{fst := fst + 1;}`.

Record updates `X@{..}` are parsed as postfix operators with higher
priority than application, so `f x y @X{q := 1}` is equivalent to `f x
(y @X{q := 1})`.

It is possible the use a record update with no argument by wrapping the
update in parentheses. See `f` in the above example.
2023-08-07 12:35:36 +02:00
Jan Mas Rovira
0cc689a2ef
Add syntax for builtin list (#2239)
- Depends on #2219 
- Closes #1643 

This pr introduces a `list` as a new builtin so that we can use syntax
sugar both in expressions and patterns. E.g. it is now possible to write
`[1; 2; 3;]`.
2023-07-03 13:24:56 +02:00
Łukasz Czajka
b4347bdd23
Numeric range types (#2232)
* Closes #2145
2023-06-28 17:24:08 +02:00
Łukasz Czajka
2fff65030b
Case folding (#2229)
Fold constant cases, i.e., convert
```
case C a b
| A := ..
| B x := ..
| C x y := M
```
to
```
let x := a;
     y := b;
in
M
```
2023-06-27 12:29:26 +02:00
Łukasz Czajka
7c039d687b
Specialization optimisation (#2164)
* Closes #2147 

Adds a `specialize` pragma which allows to specify (explicit) arguments
considered for specialization. Whenever a function is applied to a
constant known value for the specialized argument, a new version of the
function will be created with the argument pasted in. For example, the
code

```juvix
{-# specialize: [1] #-}
mymap : {A B : Type} -> (A -> B) -> List A -> List B;
mymap f nil := nil;
mymap f (x :: xs) := f x :: mymap f xs;

main : Nat;
main := length (mymap λ{x := x + 3} (1 :: 2 :: 3 :: 4 :: nil));
```

will be transformed into code equivalent to

```juvix
mymap' : (Nat -> Nat) -> List Nat -> List Nat;
mymap' f nil := nil;
mymap' f (x :: xs) := λ{x := x + 3} x :: mymap' xs;

main : Nat;
main := length (mymap' (1 :: 2 :: 3 :: 4 :: nil));
```
2023-06-26 16:49:19 +02:00
Łukasz Czajka
4c0e0b13c8
Respect fixity in runtime printer (#2182)
* Closes #2180
2023-06-07 11:44:41 +02:00
Łukasz Czajka
e9284b3ef6
Iterator syntax (#2126)
* Closes #1992 

A function identifier `fun` can be declared as an iterator with
```
syntax iterator fun;
```
For example:
```haskell
syntax iterator for;
for : {A B : Type} -> (A -> B -> A) -> A -> List B -> List A;
for f acc nil := acc;
for f acc (x :: xs) := for (f acc x) xs;
```
Iterator application syntax allows for a finite number of initializers
`acc := a` followed by a finite number of ranges `x in xs`. For example:
```
for (acc := 0) (x in lst) acc + x
```
The number of initializers plus the number of ranges must be non-zero.

An iterator application
```
fun (acc1 := a1; ..; accn := an) (x1 in b1; ..; xk in bk) body
```
gets desugared to
```
fun \{acc1 .. accn x1 .. xk := body} a1 .. an b1 .. bk
```
The `acc1`, ..., `accn`, `x1`, ..., `xk` can be patterns.

The desugaring works on a purely syntactic level. Without further
restrictions, it is not checked if the number of initializers/ranges
matches the type of the identifier. The restrictions on the number of
initializers/ranges can be specified in iterator declaration:
```
syntax iterator fun {init: n, range: k};
syntax iterator for {init: 1, range: 1};
syntax iterator map {init: 0, range: 1};
```
The attributes (`init`, `range`) in between braces are parsed as YAML to
avoid inventing and parsing a new attribute language. Both attributes
are optional.
2023-05-30 15:30:11 +02:00
Jan Mas Rovira
39b797ecfa
Add Bottom node (#2112)
- Closes #2056 
- Depends on #2103 

I am not sure about the implementation of `isType` for `NBot`. (solved).

The `Eq` instance returns `True` for every two `Bottom` terms,
regardless of their type.

---------

Co-authored-by: Jonathan Cubides <jonathan.cubides@uib.no>
Co-authored-by: Lukasz Czajka <lukasz@heliax.dev>
2023-05-23 18:31:28 +02:00
Łukasz Czajka
336a934d18
Normalization by Evaluation (#2038)
* Closes #2032.
* Adds the `juvix dev core normalize` command.
* Adds the `:n` command in JuvixCore REPL.
* Adds the `--normalize` flag to `juvix dev core read` and `juvix dev
core from-concrete`.
* Adds `pipeline-normalize` which denotes pipeline steps necessary
before normalization.
* Adds normalization tests in `tests/VampIR/positive/Core`.
2023-05-15 18:01:40 +02:00
Łukasz Czajka
8aa54ecc28
Inlining (#2036)
* Closes #1989
* Adds optimization phases to the pipline (specified by
`opt-phase-eval`, `opt-phase-exec` and `opt-phase-geb` transformations).
* Adds the `-O` option to the `compile` command to specify the
optimization level.
* Functions can be declared for inlining with the `inline` pragma:
   ```
   {-# inline: true #-}
   const : {A B : Type} -> A -> B -> A;
   const x _ := x;
   ```
By default, the function is inlined only if it's fully applied. One can
specify that a function (partially) applied to at least `n` explicit
arguments should be inlined.
   ```
   {-# inline: 2 #-}
   compose : {A B C : Type} -> (B -> C) -> (A -> B) -> A -> C;
   compose f g x := f (g x);
   ```
Then `compose f g` will be inlined, even though it's not fully applied.
But `compose f` won't be inlined.
* Non-recursive fully applied functions are automatically inlined if the
height of the body term does not exceed the inlining depth limit, which
can be specified with the `--inline` option to the `compile` command.
* The pragma `inline: false` disables automatic inlining on a
per-function basis.
2023-05-15 17:27:05 +02:00
Jan Mas Rovira
3cbf6f5cb6
Fix ordering of statements in Abstract -> Internal (#2040)
- Closes #2039 
- Closes #2055 
- Depends on #2053 

Changes in this pr:
- Local modules are removed (flattened) in the translation abstract ->
internal.
- In the translation abstract -> internal we group definitions in
mutually recursive blocks. These blocks can contain function definitions
and type definitions. Previously we only handled functions.
- The translation of Internal has been enhanced to handle these mutually
recursive blocks.
- Some improvements the pretty printer for internal (e.g. we now print
builtin tags properly).
- A "hack" that puts the builtin bool definition at the beginning of a
module if present. This was the easiest way to handle the implicit
dependency of the builtin stringToNat with bool in the internal-to-core
translation.
- A moderately sized test defining a simple lambda calculus involving
and an evaluator for it. This example showcases mutually recursive types
in juvix.

---------

Co-authored-by: Jonathan Cubides <jonathan.cubides@uib.no>
2023-05-15 13:02:09 +02:00
janmasrovira
528eaa72d0
Substitute calls after lambda lifting (#2031)
- Closes #2006

During lambda lifting, we now substitute the calls to the lifted
functions before recursively applying lambda lifting. This will slightly
increase the amount of captured variables. However, I think this is the
only way since we need all identifiers to have a type when recursing.
2023-04-26 12:56:44 +02:00
janmasrovira
5de0026d83
Add juvix global project under xdg directory and other improvements (#1963)
Co-authored-by: Paul Cadman <git@paulcadman.dev>
2023-04-13 11:27:39 +02:00
Paul Cadman
ea09ec3068
Add builtin integer type to the surface language (#1948)
This PR adds a builtin integer type to the surface language that is
compiled to the backend integer type.

## Inductive definition

The `Int` type is defined in the standard library as:

```
builtin int
type Int :=
  | --- ofNat n represents the integer n
    ofNat : Nat -> Int
  | --- negSuc n represents the integer -(n + 1)
    negSuc : Nat -> Int;
```

## New builtin functions defined in the standard library

```
intToString : Int -> String;
+ : Int -> Int -> Int;
neg : Int -> Int;
* : Int -> Int -> Int;
- : Int -> Int -> Int;
div : Int -> Int -> Int;
mod : Int -> Int -> Int;

== : Int -> Int -> Bool;
<= : Int -> Int -> Bool;
< : Int -> Int -> Bool;
```

Additional builtins required in the definition of the other builtins:

```
negNat : Nat -> Int;
intSubNat : Nat -> Nat -> Int;
nonNeg : Int -> Bool;
```

## REPL types of literals

In the REPL, non-negative integer literals have the inferred type `Nat`,
negative integer literals have the inferred type `Int`.

```
Stdlib.Prelude> :t 1
Nat
Stdlib.Prelude> :t -1
Int
:t let x : Int := 1 in x
Int
```

## The standard library Prelude

The definitions of `*`, `+`, `div` and `mod` are not exported from the
standard library prelude as these would conflict with the definitions
from `Stdlib.Data.Nat`.

Stdlib.Prelude
```
open import Stdlib.Data.Int hiding {+;*;div;mod} public;
```

* Closes https://github.com/anoma/juvix/issues/1679
* Closes https://github.com/anoma/juvix/issues/1984

---------

Co-authored-by: Lukasz Czajka <lukasz@heliax.dev>
2023-04-13 08:16:49 +01:00
Łukasz Czajka
dbd24f2f93
Check for the executable (WASM/native) pipeline prerequisites (#1970)
* Closes #1959
2023-04-04 11:58:36 +02:00
Łukasz Czajka
63a2c5144d
Print quoted strings in the runtime (#1969)
* Closes #1968
2023-04-04 10:29:02 +01:00
janmasrovira
ff495ef326
Support local modules (#1872)
Support local modules.

---------

Co-authored-by: Paul Cadman <git@paulcadman.dev>
2023-03-31 14:57:37 +01:00
Łukasz Czajka
58dbf62520
Fix removal of polymorphic type arguments (#1954)
* Closes #1930
2023-03-30 19:56:07 +02:00
janmasrovira
90a7a5e7e0
Fix REPL state to include enough information to rerun the pipeline (#1911)
Previously we were:
* discarding the types table 
* discarding the name ids state
after processing an expression in the REPL.

For example evaluating:
```
let even : _; odd : _; odd zero := false; odd (suc n) := not (even n); even zero := true; even (suc n) := not (odd n) in even 10
```
would loop in the REPL.

We noticed that the `n` in `suc n` was being given type `Type` instead
of `Nat`. This was because the name id given to n was incorrect, the
REPL started using name ids from 0 again.

We fixed this issue by storing information, including the types table
and name ids state in the Artifacts data structure that is returned when
we run the pipeline for the first time. This information is then used
when we call functions to compile / type check REPL expressions.

---------

Co-authored-by: Paul Cadman <git@paulcadman.dev>
2023-03-30 13:39:27 +02:00
Łukasz Czajka
2b5524ded1
Preserve name and location information in Internal-to-Core (#1933)
* Closes #1846 
* Preserves location information for all created `Match` nodes so that
match-to-case always has a location available.
2023-03-28 10:29:24 +02:00
Łukasz Czajka
c9b8cdd5e9
Pattern matching compilation (#1874)
This implements a basic version of the algorithm from: Luc Maranget,
[Compiling pattern matching to good decision
trees](http://moscova.inria.fr/~maranget/papers/ml05e-maranget.pdf). No
heuristics are used - the first column is always chosen.

* Closes #1798 
* Closes #1225 
* Closes #1926 
* Adds a global `--no-coverage` option which turns off coverage checking
in favour of generating runtime failures
* Changes the representation of Match patterns in JuvixCore to achieve a
more streamlined implementation
* Adds options to the Core pipeline
2023-03-27 10:42:27 +02:00
Łukasz Czajka
8d7e669f74
Fix bug with unregistered builtin bool (#1917)
* Closes #1884
2023-03-24 10:29:57 +01:00
Łukasz Czajka
2a8585ede0
Fix bug in IO runtime (#1906)
Co-authored-by: Paul Cadman <git@paulcadman.dev>
2023-03-21 14:34:46 +00:00
Łukasz Czajka
2803f3feee
Fix JuvixAsm validation (#1903)
Co-authored-by: Paul Cadman <git@paulcadman.dev>
2023-03-20 12:01:35 +00:00
Paul Cadman
51978f947c
Fix registration of builtin inductive axioms (#1901)
builtin inductive axioms must be registered in the same pass as
inductive types becuase inductive types may use builtin inductives in
the types of their constructors.

```
builtin string axiom String : Type;

type BoxedString :=
  | boxed : String -> BoxedString;
```

The separate passes for processing functions and inductives was
unnecessary. This commit combines `registerInductiveDefs` and
`registerFunctionDefs` into a single pass over a modules statements
2023-03-20 10:00:22 +00:00
Łukasz Czajka
ac6d08e259
Add errors to the Core pipeline and check GEB prerequisites (#1871)
* Depends on #1832 
* Closes #1844
* Adds errors to the Core pipeline
* Checks for no recursion in the GEB pipeline
* Checks for no polymorphism in the GEB pipeline
* Checks for no dynamic type in the GEB pipeline
* Checks for no IO in the GEB pipeline
* Checks for no unsupported builtins in the GEB pipeline
2023-03-20 10:13:07 +01:00
Paul Cadman
786ff9d075
internal-to-core: Fix index shifting of pattern arguments (#1900) 2023-03-18 00:30:51 +01:00
janmasrovira
934a273e2d
Automatically detect and split mutually recursive blocks in let expressions (#1894)
- Closes #1677
2023-03-17 11:05:55 +00:00
Łukasz Czajka
2d798ec31c
New compilation pipeline (#1832)
* Depends on PR #1824 
* Closes #1556 
* Closes #1825 
* Closes #1843
* Closes #1729 
* Closes #1596 
* Closes #1343 
* Closes #1382 
* Closes #1867 
* Closes #1876 
* Changes the `juvix compile` command to use the new pipeline.
* Removes the `juvix dev minic` command and the `BackendC` tests.
* Adds the `juvix eval` command.
* Fixes bugs in the Nat-to-integer conversion.
* Fixes bugs in the Internal-to-Core and Core-to-Core.Stripped
translations.
* Fixes bugs in the RemoveTypeArgs transformation.
* Fixes bugs in lambda-lifting (incorrect de Bruijn indices in the types
of added binders).
* Fixes several other bugs in the compilation pipeline.
* Adds a separate EtaExpandApps transformation to avoid quadratic
runtime in the Internal-to-Core translation due to repeated calls to
etaExpandApps.
* Changes Internal-to-Core to avoid generating matches on values which
don't have an inductive type.

---------

Co-authored-by: Paul Cadman <git@paulcadman.dev>
Co-authored-by: janmasrovira <janmasrovira@gmail.com>
2023-03-14 16:24:07 +01:00
Paul Cadman
c93013229a
Add compilation of complex pattern matching to case (#1824)
This PR adds the `match-to-case` Core transformation. This transforms
pattern matching nodes to a sequence of case and let nodes.

## High level description

Each branch of the match is compiled to a lambda. In the combined match 

Each branch of the match is compiled to a lambda. These lambdas are
combined in nested lets and each lambda is called in turn as each branch
gets checked. The lambda corresponding to the first branch gets called
first, if the pattern match in the branch fails, the lambda
corresponding to the next branch is called and so on. If no branches
match then a lambda is called which returns a fail node.

Conceptually:

<table>
<tr>
<td>
Core
</td>
<td>
Transformed
</td>
</tr>
<tr>
<td>

```

match v1 .. vn {
  b1
  b2
  ...
  bk
}

```

</td>
<td>

```
λ
  let c0 := λ FAIL in
    let ck := λ {...} in
      ...
      let c1 := λ {...} in
  c1 v1 ... vn

```

</td>
</tr>
</table>

The patterns on each branch are compiled to either let bindings (pattern
binders) or case expressions (constructor patterns).

Auxillary bindings are added in the case of nested constructor patterns.

The default branch in each case expression has a call to the lambda
corresponding to the next branch of the match. This is because the
default
branch is reached if the pattern match fails.

<table>

<tr>
<td>
Pattern match
</td>
<td>
Transformed
</td>
</tr>
<tr>
<td>

```
suc (suc n) ↦ n
```

</td>
<td>

```
  case ?$0 of {
    suc arg_8 := case ?$0 of {
      suc n := let n := ?$0 in n$0;
      _ := ?$2 ?$1
    };
    _ := ?$1 ?$0
  }

```

</td>
</tr>
</table>

The body of each branch is wrapped in let bindings so that the indicies
of bound
variables in the body point to the correct variables in the compiled
expression.
This is necessary because the auxiliary bindings added for nested
constructor
patterns will cause the original indicies to be offset.

Finally, the free variables in the match branch body need to be shifted
by all the bindings we've added as part of the compilation.

## Examples

### Single wildcard

<table>
<tr>
<td> Juvix </td> <td> Core </td> <td> Transformed Core </td>
</tr>
<tr>
<td>

```
f : Nat -> Nat;
f _ := 1;
```

</td>
<td>

```
λ? match ?$0 with {
  _ω309 ↦ ? 1
}
```

</td>
<td>

```
λ? let ? := λ? fail "Non-exhaustive patterns" in
   let ? := λ? let _ω309 := ?$0 in
               let _ω309 := ?$0 in 1 in
   ?$0 ?$2
```

</td>
</tr>
</table>

### Single binder

<table>
<tr>
<td> Juvix </td> <td> Core </td> <td> Transformed Core </td>
</tr>
<tr>
<td>

```
f : Nat -> Nat;
f n := n;
```

</td>
<td>

```
λ? match ?$0 with {
  n ↦ n$0
}
```

</td>
<td>

```
λ? let ? := λ? fail "Non-exhaustive patterns" in
   let ? := λ? let n := ?$0 in
               let n := ?$0 in n$0 in
   ?$0 ?$2
```

</td>
</tr>
</table>

### Single Constructor

<table>
<tr>
<td> Juvix </td> <td> Core </td> <td> Transformed Core </td>
</tr>
<tr>
<td>

```
f : Nat -> Nat;
f (suc n) := n;
```

</td>
<td>

```
λ? match ?$0 with {
  suc n ↦ n$0
}
```

</td>
<td>

```
λ? let ? := λ? fail "Non-exhaustive patterns" in let ? := λ? case ?$0 of {
  suc n := let n := ?$0 in let n := ?$0 in n$0;
  _ := ?$1 ?$0
} in ?$0 ?$2
```

</td>
</tr>
</table>

### Nested Constructor

<table>
<tr>
<td> Juvix </td> <td> Core </td> <td> Transformed Core </td>
</tr>
<tr>
<td>

```
f : Nat -> Nat;
f (suc (suc n)) := n;
```

</td>
<td>

```
λ? match ?$0 with {
  suc (suc n) ↦ n$0
}
```

</td>
<td>

```
λ? let ? := λ? fail "Non-exhaustive patterns" in let ? := λ? case ?$0 of {
  suc arg_8 := case ?$0 of {
    suc n := let n := ?$0 in let n := ?$0 in n$0;
    _ := ?$2 ?$1
  };
  _ := ?$1 ?$0
} in ?$0 ?$2
```

</td>
</tr>
</table>

### Multiple Branches

<table>
<tr>
<td> Juvix </td> <td> Core </td> <td> Transformed Core </td>
</tr>
<tr>
<td>

```
f : Nat -> Nat;
f (suc n) := n;
f zero := 0;
```

</td>
<td>

```
λ? match ?$0 with {
  suc n ↦ n$0;
  zero ↦ ? 0
}
```

</td>
<td>

```
λ? let ? := λ? fail "Non-exhaustive patterns" in let ? := λ? case ?$0 of {
  zero := ? 0;
  _ := ?$1 ?$0
} in let ? := λ? case ?$0 of {
  suc n := let n := ?$0 in let n := ?$0 in n$0;
  _ := ?$1 ?$0
} in ?$0 ?$3
```

</td>
</tr>
</table>

### Nested case with captured variable

<table>
<tr>
<td> Juvix </td> <td> Core </td> <td> Transformed Core </td>
</tr>
<tr>
<td>

```
f : Nat -> Nat -> Nat;
f n m := case m
  | suc k := n + k;
```

</td>
<td>

```
f = λ? λ? match ?$1, ?$0 with {
  n, m ↦ match m$0 with {
    suc k ↦ + n$2 k$0
  }
}
```

</td>
<td>

```
λ? λ?
  let ? := λ? λ? fail "Non-exhaustive patterns" in
  let ? := λ? λ? let n := ?$1 in let m := ?$1 in let n := ?$1 in let m := ?$1 in
      let ? := λ? fail "Non-exhaustive patterns" in let ? := λ? case ?$0 of {
            suc k := let k := ?$0 in let k := ?$0 in + n$6 k$0;
            _ := ?$1 ?$0
} in ?$0 m$2 in ?$0 ?$3 ?$2
```

</td>
</tr>
</table>

## Testing

The `tests/Compilation/positive` tests are run up to the Core evaluator
with `match-to-case` and `nat-to-int` transformations on Core turned on.

---------

Co-authored-by: Lukasz Czajka <lukasz@heliax.dev>
2023-02-15 11:30:12 +01:00
Łukasz Czajka
acea6615a4
Lazy boolean operators (#1743)
Closes #1701
2023-01-25 18:57:47 +01:00
Łukasz Czajka
ecac5e07c7 Translate 'let' to Core (#1740)
Closes #1351
2023-01-19 12:56:37 +01:00
Łukasz Czajka
6499100d67 Add test for div and mod (#1741) 2023-01-19 12:52:51 +01:00
janmasrovira
0193a33d4c
Fix inference loop (#1726) 2023-01-17 13:28:38 +01:00
janmasrovira
f7205915a5
Typecheck let expressions (#1712) 2023-01-17 09:41:07 +01:00
Łukasz Czajka
186f4f66ef
Tests for the new compilation pipeline (#1703)
Adds Juvix tests for the compilation pipeline - these are converted from
the JuvixCore tests (those that make sense). Currently, only the
translation from Juvix to JuvixCore is checked for the tests that can be
type-checked. Ultimately, the entire compilation pipeline down to native
code / WebAssembly should be checked on these tests.

Closes #1689
2023-01-12 11:22:32 +01:00