From d30dc5d5190103d76422c07b84ca250f5bc0942f Mon Sep 17 00:00:00 2001
From: milner <m@cpl0.zip>
Date: Mon, 11 Feb 2019 13:34:00 +0000
Subject: [PATCH] Define polymorphic lenses and compile the runtime library

---
 .gitignore         |  5 +++++
 META               |  3 +++
 Makefile           | 20 ++++++++++++++++++++
 README.md          |  5 +++++
 fieldglass.install |  1 +
 fieldglass.ml      |  5 +++++
 fieldglass.mli     |  5 +++++
 fieldglass.opam    | 11 +++++++++++
 runtime.ml         |  6 ++++++
 9 files changed, 61 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 META
 create mode 100644 Makefile
 create mode 100644 README.md
 create mode 100644 fieldglass.install
 create mode 100644 fieldglass.ml
 create mode 100644 fieldglass.mli
 create mode 100644 fieldglass.opam
 create mode 100644 runtime.ml

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..a959695
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,5 @@
+*.cmi
+*.cmo
+*.cma
+*.byte
+rewrite
diff --git a/META b/META
new file mode 100644
index 0000000..48cb191
--- /dev/null
+++ b/META
@@ -0,0 +1,3 @@
+version = "0.1.0"
+description = "Record accessors and composable lenses"
+archive(byte) = "fieldglass.cma"
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..fb8e9cc
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,20 @@
+OCAMLC ?= ocamlc
+
+.PHONY: all test clean
+all: fieldglass.cma
+
+fieldglass.cmi: fieldglass.mli
+	$(OCAMLC) -c $<
+
+fieldglass.cmo: fieldglass.ml fieldglass.cmi
+	$(OCAMLC) -c $<
+
+fieldglass.cma: fieldglass.cmo
+	$(OCAMLC) -a $< -o $@
+
+test: all
+	$(OCAMLC) fieldglass.cma runtime.ml -o runtime.byte
+	./runtime.byte
+
+clean:
+	rm -f *.cmi *.cmo *.cma *.byte rewrite
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..ba482fe
--- /dev/null
+++ b/README.md
@@ -0,0 +1,5 @@
+# fieldglass
+
+Lenses for reading and updating immutable data in OCaml.
+
+Build with `make`; run the checks with `make test`.
diff --git a/fieldglass.install b/fieldglass.install
new file mode 100644
index 0000000..6fc7c99
--- /dev/null
+++ b/fieldglass.install
@@ -0,0 +1 @@
+lib: ["fieldglass.cmi" "fieldglass.cma" "fieldglass.mli" "META"]
diff --git a/fieldglass.ml b/fieldglass.ml
new file mode 100644
index 0000000..d42e44d
--- /dev/null
+++ b/fieldglass.ml
@@ -0,0 +1,5 @@
+type ('s, 't, 'a, 'b) lens = ('s -> 'a) * ('b -> 's -> 't)
+type ('s, 'a) lens' = ('s, 's, 'a, 'a) lens
+
+let lens ~view ~set = view, set
+let view (get, _) = get
diff --git a/fieldglass.mli b/fieldglass.mli
new file mode 100644
index 0000000..b8055af
--- /dev/null
+++ b/fieldglass.mli
@@ -0,0 +1,5 @@
+type ('s, 't, 'a, 'b) lens = ('s -> 'a) * ('b -> 's -> 't)
+type ('s, 'a) lens' = ('s, 's, 'a, 'a) lens
+
+val lens : view:('s -> 'a) -> set:('b -> 's -> 't) -> ('s, 't, 'a, 'b) lens
+val view : ('s, 't, 'a, 'b) lens -> 's -> 'a
diff --git a/fieldglass.opam b/fieldglass.opam
new file mode 100644
index 0000000..304bbcc
--- /dev/null
+++ b/fieldglass.opam
@@ -0,0 +1,11 @@
+opam-version: "1.2"
+name: "fieldglass"
+version: "0.1.0"
+maintainer: "rack"
+authors: ["rack"]
+homepage: "https://github.com/rackquiem/fieldglass"
+bug-reports: "https://github.com/rackquiem/fieldglass/issues"
+dev-repo: "git+https://github.com/rackquiem/fieldglass.git"
+build: [make]
+build-test: [make "test"]
+available: [ocaml-version = "4.06.1"]
diff --git a/runtime.ml b/runtime.ml
new file mode 100644
index 0000000..14b0ade
--- /dev/null
+++ b/runtime.ml
@@ -0,0 +1,6 @@
+open Fieldglass
+
+let sample : (string * bool, string) lens' =
+  lens ~view:fst ~set:(fun value (_, other) -> value, other)
+
+let () = assert (view sample ("colour", true) = "colour")