Plot.plot({
marks: [
() => htl.svg`<defs>
<linearGradient id="gradient" gradientTransform="rotate(90)">
<stop offset="15%" stop-color="purple" />
<stop offset="75%" stop-color="red" />
<stop offset="100%" stop-color="gold" />
</linearGradient>
</defs>`,
Plot.barY(alphabet, {x: "letter", y: "frequency", fill: "url(#gradient)"}),
Plot.ruleY([0])
]
})