Merge pull request #13 from tidalcycles/continuous-functions

Add continuous signals (sine, cosine, saw, etc)

strudel.mjs

@@ -148,7 +148,7 @@ class TimeSpan {
         return result
     }
 
-    get midpoint() {
+    midpoint() {
         return(this.begin.add((this.end.sub(this.begin)).div(Fraction(2))))
     }
 
@@ -671,6 +671,32 @@ function steady(value) {
     return new Pattern(span => Hap(undefined, span, value))
 }
 
+export const signal = func => {
+    const query = span => [new Hap(undefined, span, func(span.midpoint()))]
+    return new Pattern(query)
+}
+
+const _toBipolar = pat => pat.fmap(x => (x * 2) - 1)
+const _fromBipolar = pat => pat.fmap(x => (x + 1) / 2)
+
+export const sine2   = signal(t => Math.sin(Math.PI * 2 * t))
+export const sine    = _fromBipolar(sine2)
+
+export const cosine2 = sine2._early(0.25)
+export const cosine  = sine._early(0.25)
+
+export const saw     = signal(t => t % 1)
+export const saw2    = _toBipolar(saw)
+
+export const isaw    = signal(t => 1 - (t % 1))
+export const isaw2   = _toBipolar(isaw)
+
+export const tri2    = fastcat(isaw2, saw2)
+export const tri     = fastcat(isaw, saw)
+
+export const square  = signal(t => Math.floor((t*2) % 2))
+export const square2 = _toBipolar(square)
+
 function reify(thing) {
     // Tunrs something into a pattern, unless it's already a pattern
     if (thing?.constructor?.name == "Pattern") {