gistfile1.txt

info esy build 0.5.6 (using package.json)
info building reason-fontkit@2.4.1@d41d8cd9
error: build failed with exit code: 1
  build log:
    # esy-build-package: building: reason-fontkit@2.4.1
    # esy-build-package: pwd: /Users/kad/.esy/source/i/reason_fontkit__2.4.1__62b9ec9c
    # esy-build-package: running: 'dune' 'build' '--root' '.'
        ocamlopt src/fontkit.cmxs (exit 2)
    (cd /Users/kad/.esy/3_____________________________________________________________________/b/reason_fontkit-2.4.1-d053e44e/default && /Users/kad/.esy/3_____________________________________________________________________/i/ocaml-4.7.1004-e5a2754f/bin/ocamlopt.opt -w @a-4-29-40-41-42-44-45-48-58-59-60-40 -strict-sequence -strict-formats -short-paths -keep-locs -g -shared -linkall -I src -o src/fontkit.cmxs src/fontkit.cmxa)
    ld: warning: directory not found for option '-L/opt/local/lib'
    ld: library not found for -lpng
    clang: error: linker command failed with exit code 1 (use -v to see invocation)
    File "caml_startup", line 1:
    Error: Error during linking
        ocamlopt bin_native/test_fontkit.exe (exit 2)
    (cd /Users/kad/.esy/3_____________________________________________________________________/b/reason_fontkit-2.4.1-d053e44e/default && /Users/kad/.esy/3_____________________________________________________________________/i/ocaml-4.7.1004-e5a2754f/bin/ocamlopt.opt -w @a-4-29-40-41-42-44-45-48-58-59-60-40 -strict-sequence -strict-formats -short-paths -keep-locs -g -o bin_native/test_fontkit.exe -I /Users/kad/.esy/3_____________________________________________________________________/i/ocaml-4.7.1004-e5a2754f/lib/ocaml/threads -I /Users/kad/.esy/3_____________________________________________________________________/i/opam__s__lwt-opam__c__4.2.1-b6eccbf5/lib/lwt -I /Users/kad/.esy/3_____________________________________________________________________/i/opam__s__lwt-opam__c__4.2.1-b6eccbf5/lib/lwt/unix -I /Users/kad/.esy/3_____________________________________________________________________/i/opam__s__mmap-opam__c__1.1.0-10184206/lib/mmap -I /Users/kad/.esy/3_____________________________________________________________________/i/opam__s__ocamlfind-opam__c__1.8.0-8971e178/lib/bytes -I /Users/kad/.esy/3_____________________________________________________________________/i/opam__s__result-opam__c__1.3-3101799f/lib/result -I /Users/kad/.esy/3_____________________________________________________________________/i/opam__s__seq-opam__c__base-3b1f4409/lib/seq -I /Users/kad/.esy/3_____________________________________________________________________/i/reason_gl_matrix-0.9.9304-468c9bea/lib/reglm -I /Users/kad/.esy/3_____________________________________________________________________/i/reason_glfw-3.2.1024-eefb804d/lib/reglfw -I src /Users/kad/.esy/3_____________________________________________________________________/i/opam__s__result-opam__c__1.3-3101799f/lib/result/result.cmxa /Users/kad/.esy/3_____________________________________________________________________/i/opam__s__lwt-opam__c__4.2.1-b6eccbf5/lib/lwt/lwt.cmxa /Users/kad/.esy/3_____________________________________________________________________/i/ocaml-4.7.1004-e5a2754f/lib/ocaml/unix.cmxa /Users/kad/.esy/3_____________________________________________________________________/i/ocaml-4.7.1004-e5a2754f/lib/ocaml/bigarray.cmxa /Users/kad/.esy/3_____________________________________________________________________/i/opam__s__mmap-opam__c__1.1.0-10184206/lib/mmap/mmap.cmxa /Users/kad/.esy/3_____________________________________________________________________/i/ocaml-4.7.1004-e5a2754f/lib/ocaml/threads/threads.cmxa /Users/kad/.esy/3_____________________________________________________________________/i/opam__s__lwt-opam__c__4.2.1-b6eccbf5/lib/lwt/unix/lwt_unix.cmxa /Users/kad/.esy/3_____________________________________________________________________/i/reason_gl_matrix-0.9.9304-468c9bea/lib/reglm/reglm.cmxa /Users/kad/.esy/3_____________________________________________________________________/i/reason_glfw-3.2.1024-eefb804d/lib/reglfw/reglfw.cmxa src/fontkit.cmxa bin_native/.test_fontkit.eobjs/native/test_fontkit.cmx)
    ld: warning: directory not found for option '-L/opt/local/lib'
    ld: library not found for -lpng
    clang: error: linker command failed with exit code 1 (use -v to see invocation)
    File "caml_startup", line 1:
    Error: Error during linking
    error: command failed: 'dune' 'build' '--root' '.' (exited with 1)
    esy-build-package: exiting with errors above...
    
  building reason-fontkit@2.4.1
esy: exiting due to errors above

Found https://stackoverflow.com/questions/17889799/libraries-in-usr-local-lib-not-found

I needed to

brew install libpng