[WIP] add a simple example for displaying the basic syntax and semantics

examples/calc/rebar.config

@@ -0,0 +1,7 @@
+{plugins, [{rebar_sesterl, {git, "https://github.com/gfngfn/rebar_sesterl_plugin.git", {branch, "master"}}}]}.
+{src_dirs, ["./_generated", "./src"]}.
+{deps, [{sesterl_stdlib, {git, "https://github.com/gfngfn/sesterl_stdlib", {tag, "v0.4.1"}}}]}.
+{profiles, [{test, [{deps, []}]}]}.
+{eunit_tests, [{dir, "_generated_test"}]}.
+{relx, [{release, {calc, "0.1.0"}, [calc]}, {dev_mode, false}]}.
+{sesterl_opts, [{output_dir, "./_generated"},{test_output_dir, "_generated_test"}]}.

examples/calc/rebar.lock

@@ -0,0 +1,4 @@
+[{<<"sesterl_stdlib">>,
+  {git,"https://github.com/gfngfn/sesterl_stdlib",
+       {ref,"0c45578e2d91d3b127135ada704e9f80b3997fd7"}},
+  0}].

examples/calc/sesterl.yaml

@@ -0,0 +1,26 @@
+package: "calc"
+language: "v0.2.0"
+
+main_module: "Calc"
+
+source_directories:
+  - "./src"
+
+dependencies:
+  - name: "sesterl_stdlib"
+    source:
+      type: "git"
+      repository: "https://github.com/gfngfn/sesterl_stdlib"
+      spec:
+        type: "tag"
+        value: "v0.4.1"
+
+erlang:
+  output_directory: "./_generated"
+  relx:
+    release:
+      name: "calc"
+      version: "0.1.0"
+      applications:
+        - "calc"
+  dev_mode: true

examples/calc/src/BinTree.sest

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+module BinTree :> sig
+  type t :: (o) -> o
+  val leaf<$a> : fun($a) -> t<$a>
+  val node<$a> : fun($a, t<$a>, t<$a>) -> t<$a>
+  val tree_size<$a> : fun(t<$a>) -> int
+end = struct
+
+  type t<$a> =
+    | Empty
+    | Node($a, t<$a>, t<$a>)
+
+  val leaf(x) =
+    Node(x, Empty, Empty)
+
+  val node(x, tree1, tree2) =
+    Node(x, tree1, tree2)
+
+  val rec tree_size(tree) =
+    case tree of
+    | Empty                 -> 0
+    | Node(_, tree1, tree2) -> 1 + tree_size(tree1) + tree_size(tree2)
+    end
+
+end

examples/calc/src/calc.app.src

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+{application, calc, [
+    {description, "calc"},
+    {vsn, "0.1.0"},
+    {registered, []},
+    {modules, []},
+    {applications, [
+        kernel,
+        stdlib
+    ]},
+    {env, []},
+    {licenses, ["MIT"]},
+    {links, []}
+]}.

examples/calc/src/calc.sest

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+module Calc :> sig
+  val fact : fun(int) -> int
+  val sum : fun(list<int>) -> int
+  val id<$a> : fun($a) -> $a
+  val swap<$a, $b> : fun({$a, $b}) -> {$b, $a}
+  val have_same_length<$a, $b> : fun(list<$a>, list<$b>) -> bool
+end = struct
+  open Stdlib
+
+  val fact(n) =
+    let rec aux(acc, n) =
+      if n <= 0 then acc else aux(n * acc, n - 1)
+    in
+    aux(1, n)
+
+  val sum(ns) =
+    List.foldl(fun(acc, n) -> acc + n end, 0, ns)
+
+  val id(x) = x
+
+  val swap({x, y}) = {y, x}
+
+  val rec have_same_length<$a, $b>(xs : list<$a>, ys : list<$b>) : bool =
+    case {xs, ys} of
+    | {[], []}                 -> true
+    | {_ :: xtail, _ :: ytail} -> have_same_length(xtail, ytail)
+    | _                        -> false
+    end
+end