initHEADmain

1 files changed, 171 insertions, 0 deletions

diff --git a/lib/functional.lua b/lib/functional.lua
new file mode 100644
index 0000000..9f50b7e
--- /dev/null
+++ b/lib/functional.lua
@@ -0,0 +1,171 @@
+--
+-- melisma - extensible and scriptable audio engine
+-- Copyright (C) 2026  Ludvig Gunne Lindström
+--
+-- This program is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation, either version 3 of the License, or
+-- (at your option) any later version.
+--
+-- This program is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+-- GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License
+-- along with this program.  If not, see <https://www.gnu.org/licenses/>.
+--
+
+local m_util = require 'melisma.util'
+
+local M = {}
+
+function M.fmap(f,l)
+  local res = {}
+  for k,v in pairs(l) do res[k] = f(v) end
+  return res
+end
+
+function M.compose(f,g,...)
+  local tail = table.pack(...)
+  if g == nil then return f end
+  return function(x) return f(M.compose(g,table.unpack(tail))(x)) end
+end
+
+function M.pipeline(...)
+  local args = table.pack(...)
+  return function(x)
+    for _,f in ipairs(args) do x = f(x) end
+    return x
+  end
+end
+
+function M.bind(f,...)
+  local bound = table.pack(...)
+  return function(...)
+    local free = table.pack(...)
+    local all = M.concat(bound,free)
+    return f(table.unpack(all))
+  end
+end
+
+function M.bind1(f,...)
+  local bound = table.pack(...)
+  return function(x)
+    return f(x,table.unpack(bound))
+  end
+end
+
+function M.constval(v) return function(...) return v end end
+
+function M.constfunc(f) return function(...) f() end end
+
+function M.call(f,...) return f(...) end
+
+function M.replicate(f,n)
+  local res = {}
+  for i=1,n do
+    if type(f) == 'function' then
+      table.insert(res,f())
+    else
+      table.insert(res,f)
+    end
+  end
+  return res
+end
+
+function M.id(...) return ... end
+
+function M.access(...)
+  local args = table.pack(...)
+  local x = args[#args]
+  args[#args] = nil
+
+  for _,key in ipairs(args) do
+    x = x[key]
+  end
+
+  return x
+end
+
+function M.filter(pred,list)
+  local result = {}
+
+  for _,elem in ipairs(list) do
+    if pred(elem) then
+      table.insert(result,elem)
+    end
+  end
+
+  return result
+end
+
+function M.void(...) end
+
+function M.zip(f,lhs,rhs)
+  local result = {}
+  local n = math.min(#lhs,#rhs)
+
+  for i = 1,n do
+    local v = f(lhs[i],rhs[i])
+    table.insert(result,v)
+  end
+
+  return result
+end
+
+function M.tap(f)
+  return function(...)
+    f(...)
+    return ...
+  end
+end
+
+function M.fold(mempty,mappend,tbl)
+	local result = mempty
+	for i = 1,#tbl do result = mappend(result,tbl) end
+	return result
+end
+
+function M.flatten(tbl)
+	if type(tbl) ~= 'table' then return tbl end
+	return M.fold({}, M.concat, fmap(M.flatten, tbl))
+end
+
+function M.concat(lhs,rhs)
+  local result = {}
+  for i = 1,#lhs do result[i] = lhs[i] end
+  for i = 1,#rhs do result[i + #lhs] = rhs[i] end
+  return result
+end
+
+function M.find(list,pred)
+  for i = 1,#list do
+    if pred(list[i]) then return list[i],i end
+  end
+  return nil,nil
+end
+
+function M.range(f,t,s)
+  local res = {}
+  for x = f,t,s or 1 do table.insert(res,x) end
+  return res
+end
+
+function M.image(a,b,c,d,x) return (x - a)/(b - a)*(d - c) + c end
+
+function M.apply(f,...) return f(...) end
+
+function M.once(f)
+  local ret
+  local called = false
+  return function(...)
+    if not called then
+      ret = f(...)
+      called = true
+      return ret
+    end
+  end
+end
+
+return M