commit 0cb01daaa05ff88864c075a1e2728fdc6a21d5fe
Author: sneeker <s@cpl0.zip>
Date:   Mon Feb 11 13:34:00 2019 +0000

    Define polymorphic lenses and compile the runtime library

diff --git a/.gitignore b/.gitignore
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index 0000000..a959695
--- /dev/null
+++ b/.gitignore
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+*.cmi
+*.cmo
+*.cma
+*.byte
+rewrite
diff --git a/META b/META
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index 0000000..48cb191
--- /dev/null
+++ b/META
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+version = "0.1.0"
+description = "Record accessors and composable lenses"
+archive(byte) = "fieldglass.cma"
diff --git a/Makefile b/Makefile
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index 0000000..fb8e9cc
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+++ b/Makefile
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+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
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+++ b/README.md
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+# 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
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index 0000000..6fc7c99
--- /dev/null
+++ b/fieldglass.install
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+lib: ["fieldglass.cmi" "fieldglass.cma" "fieldglass.mli" "META"]
diff --git a/fieldglass.ml b/fieldglass.ml
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+++ b/fieldglass.ml
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+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
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+++ b/fieldglass.mli
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+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
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+++ b/fieldglass.opam
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+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
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index 0000000..14b0ade
--- /dev/null
+++ b/runtime.ml
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+open Fieldglass
+
+let sample : (string * bool, string) lens' =
+  lens ~view:fst ~set:(fun value (_, other) -> value, other)
+
+let () = assert (view sample ("colour", true) = "colour")