diff --git a/purescript/switcheroo/.gitignore b/purescript/switcheroo/.gitignore
new file mode 100644
index 0000000..1081dbc
--- /dev/null
+++ b/purescript/switcheroo/.gitignore
@@ -0,0 +1,11 @@
+/bower_components/
+/node_modules/
+/.pulp-cache/
+/output/
+/generated-docs/
+/.psc-package/
+/.psc*
+/.purs*
+/.psa*
+/.spago
+main.js
diff --git a/purescript/switcheroo/flake.lock b/purescript/switcheroo/flake.lock
new file mode 100644
index 0000000..e3ffc2e
--- /dev/null
+++ b/purescript/switcheroo/flake.lock
@@ -0,0 +1,640 @@
+{
+  "nodes": {
+    "deadnix": {
+      "inputs": {
+        "fenix": "fenix",
+        "naersk": "naersk",
+        "nixpkgs": "nixpkgs_4",
+        "utils": "utils"
+      },
+      "locked": {
+        "lastModified": 1655647809,
+        "narHash": "sha256-npyHYIJW7HyGIFpCZZK+t5JM/v2LsyFhAGJxX1DXO7E=",
+        "owner": "astro",
+        "repo": "deadnix",
+        "rev": "83c42cc64d190ecb72f5929eab0f64fe88e25dc4",
+        "type": "github"
+      },
+      "original": {
+        "owner": "astro",
+        "repo": "deadnix",
+        "type": "github"
+      }
+    },
+    "deadnix_2": {
+      "inputs": {
+        "fenix": "fenix_2",
+        "naersk": "naersk_2",
+        "nixpkgs": "nixpkgs_8",
+        "utils": "utils_2"
+      },
+      "locked": {
+        "lastModified": 1656370114,
+        "narHash": "sha256-XBbSWeBuF6Ck0jc634yAp2hjPXWM2JyRDPCdK0dh3w4=",
+        "owner": "astro",
+        "repo": "deadnix",
+        "rev": "9f450f7250ad7680cb5f12ce5985cc18496c2d5f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "astro",
+        "repo": "deadnix",
+        "type": "github"
+      }
+    },
+    "docs-search": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1661787609,
+        "narHash": "sha256-jgOl8PKisRmcaHOya3HzArI3eKjVErx+XIBGminh9Zk=",
+        "owner": "purs-nix",
+        "repo": "purescript-docs-search",
+        "rev": "4620575e21886fcbf516d0b43910ba4ead2a60d0",
+        "type": "github"
+      },
+      "original": {
+        "owner": "purs-nix",
+        "repo": "purescript-docs-search",
+        "type": "github"
+      }
+    },
+    "fenix": {
+      "inputs": {
+        "nixpkgs": "nixpkgs_2",
+        "rust-analyzer-src": "rust-analyzer-src"
+      },
+      "locked": {
+        "lastModified": 1655533500,
+        "narHash": "sha256-qJJmLVoMYfDLywI9MNL7sb0W/GsKQF9HDatdHm1tSl0=",
+        "owner": "nix-community",
+        "repo": "fenix",
+        "rev": "b6630603af13df17d0dd4df8629e9a24e6ba0fbd",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "fenix",
+        "type": "github"
+      }
+    },
+    "fenix_2": {
+      "inputs": {
+        "nixpkgs": "nixpkgs_6",
+        "rust-analyzer-src": "rust-analyzer-src_2"
+      },
+      "locked": {
+        "lastModified": 1655533500,
+        "narHash": "sha256-qJJmLVoMYfDLywI9MNL7sb0W/GsKQF9HDatdHm1tSl0=",
+        "owner": "nix-community",
+        "repo": "fenix",
+        "rev": "b6630603af13df17d0dd4df8629e9a24e6ba0fbd",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "fenix",
+        "type": "github"
+      }
+    },
+    "fenix_3": {
+      "inputs": {
+        "nixpkgs": [
+          "purs-nix",
+          "statix",
+          "nixpkgs"
+        ],
+        "rust-analyzer-src": "rust-analyzer-src_3"
+      },
+      "locked": {
+        "lastModified": 1645251813,
+        "narHash": "sha256-cQ66tGjnZclBCS3nD26mZ5fUH+3/HnysGffBiWXUSHk=",
+        "owner": "nix-community",
+        "repo": "fenix",
+        "rev": "9892337b588c38ec59466a1c89befce464aae7f8",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "fenix",
+        "type": "github"
+      }
+    },
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1618217525,
+        "narHash": "sha256-WGrhVczjXTiswQaoxQ+0PTfbLNeOQM6M36zvLn78AYg=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "c6169a2772643c4a93a0b5ac1c61e296cba68544",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "flake-utils_2": {
+      "locked": {
+        "lastModified": 1618217525,
+        "narHash": "sha256-WGrhVczjXTiswQaoxQ+0PTfbLNeOQM6M36zvLn78AYg=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "c6169a2772643c4a93a0b5ac1c61e296cba68544",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "get-flake": {
+      "locked": {
+        "lastModified": 1644686428,
+        "narHash": "sha256-zkhYsURWFrvEZLkIoBeqFBzSu+cA2u5mo6M8vq9LN7M=",
+        "owner": "ursi",
+        "repo": "get-flake",
+        "rev": "703f15558daa56dfae19d1858bb3046afe68831a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "ursi",
+        "repo": "get-flake",
+        "type": "github"
+      }
+    },
+    "gitignore": {
+      "inputs": {
+        "nixpkgs": [
+          "purs-nix",
+          "statix",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1635165013,
+        "narHash": "sha256-o/BdVjNwcB6jOmzZjOH703BesSkkS5O7ej3xhyO8hAY=",
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "rev": "5b9e0ff9d3b551234b4f3eb3983744fa354b17f1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "type": "github"
+      }
+    },
+    "make-shell": {
+      "locked": {
+        "lastModified": 1634940815,
+        "narHash": "sha256-P69OmveboXzS+es1vQGS4bt+ckwbeIExqxfGLjGuJqA=",
+        "owner": "ursi",
+        "repo": "nix-make-shell",
+        "rev": "8add91681170924e4d0591b22f294aee3f5516f9",
+        "type": "github"
+      },
+      "original": {
+        "owner": "ursi",
+        "ref": "1",
+        "repo": "nix-make-shell",
+        "type": "github"
+      }
+    },
+    "make-shell_2": {
+      "locked": {
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+        "narHash": "sha256-P69OmveboXzS+es1vQGS4bt+ckwbeIExqxfGLjGuJqA=",
+        "owner": "ursi",
+        "repo": "nix-make-shell",
+        "rev": "8add91681170924e4d0591b22f294aee3f5516f9",
+        "type": "github"
+      },
+      "original": {
+        "owner": "ursi",
+        "ref": "1",
+        "repo": "nix-make-shell",
+        "type": "github"
+      }
+    },
+    "naersk": {
+      "inputs": {
+        "nixpkgs": "nixpkgs_3"
+      },
+      "locked": {
+        "lastModified": 1655042882,
+        "narHash": "sha256-9BX8Fuez5YJlN7cdPO63InoyBy7dm3VlJkkmTt6fS1A=",
+        "owner": "nix-community",
+        "repo": "naersk",
+        "rev": "cddffb5aa211f50c4b8750adbec0bbbdfb26bb9f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "naersk",
+        "type": "github"
+      }
+    },
+    "naersk_2": {
+      "inputs": {
+        "nixpkgs": "nixpkgs_7"
+      },
+      "locked": {
+        "lastModified": 1655042882,
+        "narHash": "sha256-9BX8Fuez5YJlN7cdPO63InoyBy7dm3VlJkkmTt6fS1A=",
+        "owner": "nix-community",
+        "repo": "naersk",
+        "rev": "cddffb5aa211f50c4b8750adbec0bbbdfb26bb9f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-community",
+        "repo": "naersk",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1675698036,
+        "narHash": "sha256-BgsQkQewdlQi8gapJN4phpxkI/FCE/2sORBaFcYbp/A=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "1046c7b92e908a1202c0f1ba3fc21d19e1cf1b62",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_10": {
+      "locked": {
+        "lastModified": 1645013224,
+        "narHash": "sha256-b7OEC8vwzJv3rsz9pwnTX2LQDkeOWz2DbKypkVvNHXc=",
+        "owner": "nixos",
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+        "rev": "b66b39216b1fef2d8c33cc7a5c72d8da80b79970",
+        "type": "github"
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+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_2": {
+      "locked": {
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+        "narHash": "sha256-49OBVVRgb9H/PSmNT9W61+NRdDbuSJVuDDflwXlaUKU=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "3d7435c638baffaa826b85459df0fff47f12317d",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_3": {
+      "locked": {
+        "lastModified": 1655481042,
+        "narHash": "sha256-XHbcywq2vIQ5CeH1OK3TN793jkiNAAZsSctS1PFgseo=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "103a4c0ae46afa9cf008c30744175315ca38e9f9",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "nixpkgs_4": {
+      "locked": {
+        "lastModified": 1655481042,
+        "narHash": "sha256-XHbcywq2vIQ5CeH1OK3TN793jkiNAAZsSctS1PFgseo=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "103a4c0ae46afa9cf008c30744175315ca38e9f9",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "nixpkgs_5": {
+      "locked": {
+        "lastModified": 1646506091,
+        "narHash": "sha256-sWNAJE2m+HOh1jtXlHcnhxsj6/sXrHgbqVNcVRlveK4=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "3e644bd62489b516292c816f70bf0052c693b3c7",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_6": {
+      "locked": {
+        "lastModified": 1655400192,
+        "narHash": "sha256-49OBVVRgb9H/PSmNT9W61+NRdDbuSJVuDDflwXlaUKU=",
+        "owner": "nixos",
+        "repo": "nixpkgs",
+        "rev": "3d7435c638baffaa826b85459df0fff47f12317d",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nixos",
+        "ref": "nixos-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "nixpkgs_7": {
+      "locked": {
+        "lastModified": 1655481042,
+        "narHash": "sha256-XHbcywq2vIQ5CeH1OK3TN793jkiNAAZsSctS1PFgseo=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "103a4c0ae46afa9cf008c30744175315ca38e9f9",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "nixpkgs_8": {
+      "locked": {
+        "lastModified": 1655481042,
+        "narHash": "sha256-XHbcywq2vIQ5CeH1OK3TN793jkiNAAZsSctS1PFgseo=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "103a4c0ae46afa9cf008c30744175315ca38e9f9",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "nixpkgs_9": {
+      "locked": {
+        "lastModified": 1656549732,
+        "narHash": "sha256-eILutFZGjfk2bEzfim8S/qyYc//0S1KsCeO+OWbtoR0=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "d3248619647234b5dc74a6921bcdf6dd8323eb22",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "parsec": {
+      "locked": {
+        "lastModified": 1635533376,
+        "narHash": "sha256-/HrG0UPGnI5VdkhrNrpDiM2+nhdL6lD/bqyGtYv0QDE=",
+        "owner": "nprindle",
+        "repo": "nix-parsec",
+        "rev": "1bf25dd9c5de1257a1c67de3c81c96d05e8beb5e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nprindle",
+        "repo": "nix-parsec",
+        "type": "github"
+      }
+    },
+    "ps-tools": {
+      "inputs": {
+        "deadnix": "deadnix_2",
+        "make-shell": "make-shell_2",
+        "nixpkgs": "nixpkgs_9",
+        "utils": "utils_3"
+      },
+      "locked": {
+        "lastModified": 1658374818,
+        "narHash": "sha256-WxbQ/BR4Ep8tBbaOikXechspyZlvwfL5XNmRNEnaOFo=",
+        "owner": "purs-nix",
+        "repo": "purescript-tools",
+        "rev": "c0f887f60ea2331dfdc5b0e8be2e732976887345",
+        "type": "github"
+      },
+      "original": {
+        "owner": "purs-nix",
+        "repo": "purescript-tools",
+        "type": "github"
+      }
+    },
+    "purs-nix": {
+      "inputs": {
+        "deadnix": "deadnix",
+        "docs-search": "docs-search",
+        "get-flake": "get-flake",
+        "make-shell": "make-shell",
+        "nixpkgs": "nixpkgs_5",
+        "parsec": "parsec",
+        "ps-tools": "ps-tools",
+        "statix": "statix",
+        "utils": "utils_4"
+      },
+      "locked": {
+        "lastModified": 1674243319,
+        "narHash": "sha256-o39rBVSNqchahHrMYNixdlasDro8omlf/n7yQZsdNI8=",
+        "owner": "purs-nix",
+        "repo": "purs-nix",
+        "rev": "2b7761ffaded363d0d00afe320350cc5c9ee9012",
+        "type": "github"
+      },
+      "original": {
+        "owner": "purs-nix",
+        "ref": "ps-0.15",
+        "repo": "purs-nix",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs",
+        "ps-tools": [
+          "purs-nix",
+          "ps-tools"
+        ],
+        "purs-nix": "purs-nix",
+        "utils": "utils_5"
+      }
+    },
+    "rust-analyzer-src": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1655507737,
+        "narHash": "sha256-o+AqNsjL6o2RHh4InZHQVpkmqg570YFJL4Db8mKq+fs=",
+        "owner": "rust-lang",
+        "repo": "rust-analyzer",
+        "rev": "12dd81092e37df28b7a3591cae9675e668927198",
+        "type": "github"
+      },
+      "original": {
+        "owner": "rust-lang",
+        "ref": "nightly",
+        "repo": "rust-analyzer",
+        "type": "github"
+      }
+    },
+    "rust-analyzer-src_2": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1655507737,
+        "narHash": "sha256-o+AqNsjL6o2RHh4InZHQVpkmqg570YFJL4Db8mKq+fs=",
+        "owner": "rust-lang",
+        "repo": "rust-analyzer",
+        "rev": "12dd81092e37df28b7a3591cae9675e668927198",
+        "type": "github"
+      },
+      "original": {
+        "owner": "rust-lang",
+        "ref": "nightly",
+        "repo": "rust-analyzer",
+        "type": "github"
+      }
+    },
+    "rust-analyzer-src_3": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1645205556,
+        "narHash": "sha256-e4lZW3qRyOEJ+vLKFQP7m2Dxh5P44NrnekZYLxlucww=",
+        "owner": "rust-analyzer",
+        "repo": "rust-analyzer",
+        "rev": "acf5874b39f3dc5262317a6074d9fc7285081161",
+        "type": "github"
+      },
+      "original": {
+        "owner": "rust-analyzer",
+        "ref": "nightly",
+        "repo": "rust-analyzer",
+        "type": "github"
+      }
+    },
+    "statix": {
+      "inputs": {
+        "fenix": "fenix_3",
+        "gitignore": "gitignore",
+        "nixpkgs": "nixpkgs_10"
+      },
+      "locked": {
+        "lastModified": 1657460333,
+        "narHash": "sha256-5o6zMBASEsGKtjKDb3SizJnN9A7qpOcbzWBXsacfMyc=",
+        "owner": "nerdypepper",
+        "repo": "statix",
+        "rev": "6422c959d365dee2fda5eda8858fefad31f17b25",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nerdypepper",
+        "repo": "statix",
+        "type": "github"
+      }
+    },
+    "utils": {
+      "locked": {
+        "lastModified": 1653893745,
+        "narHash": "sha256-0jntwV3Z8//YwuOjzhV2sgJJPt+HY6KhU7VZUL0fKZQ=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "1ed9fb1935d260de5fe1c2f7ee0ebaae17ed2fa1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "utils_2": {
+      "locked": {
+        "lastModified": 1653893745,
+        "narHash": "sha256-0jntwV3Z8//YwuOjzhV2sgJJPt+HY6KhU7VZUL0fKZQ=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "1ed9fb1935d260de5fe1c2f7ee0ebaae17ed2fa1",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "utils_3": {
+      "inputs": {
+        "flake-utils": "flake-utils"
+      },
+      "locked": {
+        "lastModified": 1656044990,
+        "narHash": "sha256-f01BB7CaOyntOab9XnpH9HD63rGcnu2iyL4M2ubs5F8=",
+        "owner": "ursi",
+        "repo": "flake-utils",
+        "rev": "f53b674a2c90f6202a2f4cd491aba121775490b5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "ursi",
+        "ref": "8",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "utils_4": {
+      "inputs": {
+        "flake-utils": "flake-utils_2"
+      },
+      "locked": {
+        "lastModified": 1656044990,
+        "narHash": "sha256-f01BB7CaOyntOab9XnpH9HD63rGcnu2iyL4M2ubs5F8=",
+        "owner": "ursi",
+        "repo": "flake-utils",
+        "rev": "f53b674a2c90f6202a2f4cd491aba121775490b5",
+        "type": "github"
+      },
+      "original": {
+        "owner": "ursi",
+        "ref": "8",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "utils_5": {
+      "locked": {
+        "lastModified": 1667395993,
+        "narHash": "sha256-nuEHfE/LcWyuSWnS8t12N1wc105Qtau+/OdUAjtQ0rA=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "5aed5285a952e0b949eb3ba02c12fa4fcfef535f",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/purescript/switcheroo/flake.nix b/purescript/switcheroo/flake.nix
new file mode 100644
index 0000000..40298d6
--- /dev/null
+++ b/purescript/switcheroo/flake.nix
@@ -0,0 +1,53 @@
+{ inputs =
+    { nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+      ps-tools.follows = "purs-nix/ps-tools";
+      purs-nix.url = "github:purs-nix/purs-nix/ps-0.15";
+      utils.url = "github:numtide/flake-utils";
+    };
+
+  outputs = { nixpkgs, utils, ... }@inputs:
+    utils.lib.eachSystem [ "x86_64-linux" "x86_64-darwin" ]
+      (system:
+         let
+           pkgs = nixpkgs.legacyPackages.${system};
+           ps-tools = inputs.ps-tools.legacyPackages.${system};
+           purs-nix = inputs.purs-nix { inherit system; };
+
+           ps =
+             purs-nix.purs
+               { dependencies =
+                   with purs-nix.ps-pkgs;
+                   [ console
+                     effect
+                     prelude
+                     exists
+                     tuples
+                     indexed-monad
+                     aff
+                   ];
+
+                 dir = ./.;
+               };
+         in
+         { packages.default = ps.bundle {};
+
+           devShells.default =
+             pkgs.mkShell
+               { packages =
+                   with pkgs;
+                   [ entr
+                     nodejs
+                     (ps.command {})
+                     ps-tools.for-0_15.purescript-language-server
+                     purs-nix.esbuild
+                     purs-nix.purescript
+                   ];
+
+                 shellHook =
+                   ''
+                   alias watch="find src | entr -s 'echo bundling; purs-nix bundle'"
+                   '';
+               };
+         }
+      );
+}
diff --git a/purescript/switcheroo/src/Main.purs b/purescript/switcheroo/src/Main.purs
new file mode 100644
index 0000000..c47010b
--- /dev/null
+++ b/purescript/switcheroo/src/Main.purs
@@ -0,0 +1,122 @@
+module Main where
+
+import Prelude
+
+import Control.Monad.Indexed.Qualified as Ix
+import Data.Array as Array
+import Data.Identity (Identity(..))
+import Effect (Effect)
+import Effect.Console (log)
+import Safe.Coerce (coerce)
+import Swictheroo.Stream (ConsumeM, Producer, constantProducer, runConsumeM_, unitProducer)
+import Swictheroo.Stream as Stream
+
+type Producers m =
+  { download :: Producer m Int
+  , reportDownload :: Producer m String
+  , ping :: Producer m Boolean
+  }
+
+program :: forall m. Monad m => Producers m -> ConsumeM m Unit Unit String
+program producers = Ix.do
+  Stream.replace producers.download
+  a <- Stream.pull
+
+  Stream.replace producers.reportDownload
+  b <- Stream.pull
+
+  Stream.replace producers.ping
+  c <- Stream.pull
+
+  Stream.replace unitProducer
+
+  pure $ Array.fold
+    [ "Download: "
+    , show a
+    , ", Report: "
+    , show b
+    , ", Ping: "
+    , show c
+    ]
+
+{-
+Pseudo-code for testing:
+
+data SyntheticEvent = Download Int | Report String | Ping Int
+
+producers =
+  { download: case _ of
+    Download s -> Just s
+    _ -> Nothing
+  , report: ...
+  , ping: ... 
+  }
+
+story =
+  [ Emit (Download 7)
+  , Expect Cancel
+  , Emit (Report 7)
+  , Expect Cancel
+  , Emit (Ping 7)
+  , Expect Cancel
+  ] 
+-}
+
+{- How do we cancel our program?
+
+The program would require an extra producer called "cancel".
+Every time we call "Stream.replace", we would merge "cancel" with 
+the respective new stream. This way, when we call "Stream.pull" we can
+either receive a "Left" (which means we must cancel) or a "Right" 
+(which means we have gotten our value and can keep going).
+-}
+
+{- All async effects should be avoided outside the internals of our monad!
+
+Eg: do 
+  a <- lift $ Aff.wait ...
+
+This is *bad*, because it means we cannot receive a cancellation event. 
+
+A better idea would be:
+do 
+  Stream.mapSource (\old -> merge old (fromAff (Aff.wait ...)))
+
+  result <- Stream.pull
+
+  case result of
+    -- Our effect finished running!
+    Left effectResult -> do
+       -- Return to old producer
+       Stream.mapSource Either.hush
+       -- Do stuff with the result of the effect
+       ...
+
+    -- Try again later!
+    Right otherResult -> do
+       -- Handle the other result
+       ... 
+
+This does not block the other events at any point!
+Although this might look complicated, it's possible to create helpers for 
+common patterns like this one!
+
+Note that in an actual production codebase we would receive
+  (fromAff (Aff.wait ...)) from the exterior in order to
+  allow mocking and to not tie ourselves to a specific monad.
+-}
+
+{- One cool thing about this approach is 
+that simple state can be kept without the need for StateT!
+(because we can simply pass around values)
+-}
+
+main :: Effect Unit
+main = log (coerce result)
+  where
+  result :: Identity _
+  result = runConsumeM_ $ program
+    { download: constantProducer 3
+    , reportDownload: constantProducer "foo"
+    , ping: constantProducer true
+    }
diff --git a/purescript/switcheroo/src/Stream.purs b/purescript/switcheroo/src/Stream.purs
new file mode 100644
index 0000000..4b117a9
--- /dev/null
+++ b/purescript/switcheroo/src/Stream.purs
@@ -0,0 +1,167 @@
+module Swictheroo.Stream where
+
+import Prelude
+
+import Control.Alt (class Alt)
+import Control.Alternative (class Plus, (<|>))
+import Control.Applicative.Indexed (class IxApplicative, class IxApply, class IxFunctor)
+import Control.Bind.Indexed (class IxBind)
+import Control.Monad.Indexed (class IxMonad, iap, iapply, ibind, imap, ipure)
+import Control.Parallel (parOneOf, parSequence_)
+import Data.Bifunctor (bimap)
+import Data.Either (Either(..))
+import Data.Lazy (Lazy)
+import Data.Lazy as Lazy
+import Data.Maybe (Maybe(..))
+import Data.Profunctor.Strong (first)
+import Data.Tuple.Nested (type (/\), (/\))
+import Effect.Aff (Aff, never)
+
+-- | A producer can:
+-- | - Produce values
+-- | - Destroy itself
+newtype Producer m a =
+  Producer
+    { destroy :: m Unit
+    -- | Producers advance to a new version once they produce a value.
+    -- | This allows pure producers to exist. For example, a pure producer
+    -- | could hold an array of events, return the first one, and then create
+    -- | a new producer from the tail of the array
+    , produce :: m (Lazy (a /\ Producer m a))
+    }
+
+produce :: forall m i. Monad m => Producer m i -> m (i /\ Producer m i)
+produce (Producer producer) = producer.produce <#> Lazy.force
+
+destroyProducer :: forall m i. Monad m => Producer m i -> m Unit
+destroyProducer (Producer producer) = producer.destroy
+
+constantProducer :: forall m a. Monad m => a -> Producer m a
+constantProducer value = Producer
+  { destroy: pure unit
+  , produce: pure $ Lazy.defer \_ -> value /\ (constantProducer value)
+  }
+
+unitProducer :: forall m. Monad m => Producer m Unit
+unitProducer = constantProducer unit
+
+filterMapProducer :: forall a b m. Monad m => (a -> Maybe b) -> Producer m a -> Producer m b
+filterMapProducer f producer = Producer
+  { destroy: destroyProducer producer
+  , produce: loop producer
+  }
+  where
+  -- Keeps producing values until one matches the given predicate!
+  loop producer = do
+    value /\ producer' <- produce producer
+    case f value of
+      Nothing -> loop producer'
+      Just updated -> pure $ Lazy.defer \_ -> updated /\ (filterMapProducer f producer')
+
+-- | Type parameter explanation:
+-- | - m = underlying monad
+-- | - i = what the producer present when 
+-- |   the computation *starts* needs to produce
+-- | - o = what the producer present when 
+-- |   the computation *ends* needs to produce
+-- | - a = result of the computation
+-- |
+-- | This monad encapsulates the followin 3 operations:
+-- | - Consuming values from a producer
+-- | - Cancelling + replacing the current producer with a different one.
+newtype ConsumeM m i o a = ConsumeM
+  ( Producer m i -> m (a /\ Producer m o)
+  )
+
+pull :: forall m i. Monad m => ConsumeM m i i i
+pull = ConsumeM produce
+
+replace :: forall m i o. Monad m => Producer m o -> ConsumeM m i o Unit
+replace producer' = ConsumeM \producer -> do
+  destroyProducer producer
+  pure (unit /\ producer')
+
+lift :: forall m i a. Monad m => m a -> ConsumeM m i i a
+lift computation = ConsumeM \producer -> do
+  result <- computation
+  pure (result /\ producer)
+
+producer :: forall m i. Monad m => ConsumeM m i i (Producer m i)
+producer = ConsumeM \p -> pure (p /\ p)
+
+mapSource :: forall m i o. Monad m => (Producer m i -> Producer m o) -> ConsumeM m i o Unit
+mapSource f = ConsumeM \producer -> do
+  pure (unit /\ f producer)
+
+runConsumeM :: forall m i o a. Monad m => Producer m i -> ConsumeM m i o a -> m a
+runConsumeM producer (ConsumeM run) = do
+  result /\ producer' <- run producer
+  destroyProducer producer'
+  pure result
+
+runConsumeM_ :: forall m a o. Monad m => ConsumeM m Unit o a -> m a
+runConsumeM_ = runConsumeM unitProducer
+
+---------- Typeclass instances
+instance Functor m => Functor (Producer m) where
+  map f (Producer producer) = Producer
+    { destroy: producer.destroy
+    , produce: producer.produce <#> map (bimap f (map f))
+    }
+
+instance Functor m => IxFunctor (ConsumeM m) where
+  imap f (ConsumeM consumer) = ConsumeM
+    \producer -> consumer producer <#> first f
+
+instance Functor m => Functor (ConsumeM m i i) where
+  map = imap
+
+instance Monad m => IxApply (ConsumeM m) where
+  iapply = iap
+
+instance Monad m => Apply (ConsumeM m i i) where
+  apply = iapply
+
+instance Monad m => IxApplicative (ConsumeM m) where
+  ipure a = ConsumeM \p -> pure (a /\ p)
+
+instance Monad m => Applicative (ConsumeM m i i) where
+  pure = ipure
+
+instance Monad m => IxBind (ConsumeM m) where
+  ibind (ConsumeM consumer) f = ConsumeM
+    \producer -> do
+      result /\ producer' <- consumer producer
+      let (ConsumeM consumer') = f result
+      consumer' producer'
+
+instance Monad m => Bind (ConsumeM m i i) where
+  bind = ibind
+
+instance Monad m => IxMonad (ConsumeM m)
+instance Monad m => Monad (ConsumeM m i i)
+
+---------- Merge producers
+type AffProducer = Producer Aff
+
+instance Alt AffProducer where
+  alt first second = Producer
+    { destroy:
+        parSequence_
+          [ destroyProducer first
+          , destroyProducer second
+          ]
+    , produce: ado
+        result <- parOneOf
+          [ produce first <#> Left
+          , produce second <#> Right
+          ]
+        in
+          pure case result of
+            Left (result /\ first') -> result /\ (first' <|> second)
+            Right (result /\ second') -> result /\ (first <|> second')
+    }
+
+instance Plus AffProducer where
+  empty = Producer { destroy: pure unit, produce: never }
+